Category Archives: Magazine Articles

Acceleration Gapp

Editors Note: This article originally appeared in the ‘Speed and Supercar magazine, April 1973


AccelerationGapp Image 1

The ‘Shotgun Express’ by Wayne Gapp and Jack Roush is a ’72 Maverick with 429 power that lives up to its name

By Alex Warlordy

A fantastic amount of chassis work went into this machine, much of it detailed on a Bridgeport mill. For instance, the outriggers that carry the removable body are fully boxed, and tapered from the chassis on out to save weight. Welded tubes at the outer end of each outrigger provide an access path to the body retaining nuts.The goal was a 3125 pound weight with a full 55 percent resting on the rear wheels, and this is met with room to spare.


‘Glass lid over the trunk conceals an ample amount of ballast and reinforcements, designed to put a full 55 percent of the vehicle’s weight over the rear wheels.

The six months work project began with Bill Jamieson and Al Buckmaster of the Gapp and Roush team stripping the entire car down to the metal and cutting out large sections front and rear. Working with chassis builder Tom Smith, they fabricated a completed new subframe of 2 x 3 chrome moly tubing with a .090 wall. This, plus a complete roll bar cage and an assortment of struts, results in a chassis that is so stiff that it will stand on three jacks as easily as on four!

AccelerationGapp Image 2From left to right; Jack Roush, Wayne Gapp (former Ford Motor Co. engineer), Bill Jameson and Al Buckmaster built this 429 Boss into one of the fastest “Better Ideas” around today’s 1320 scene.

All of the original front sheet metal is gone, together with the torque boxes, replaced to good advantage by the roll cage. Another heavy section of the car that includes the rear wheel wells and the front floor area was chiseled out and discarded. To manufacture a new set of wheel wells with neatly rounded edges,the Gapp and Roush team first used a Greenlee tube benderto make up a buck of that shape.The sheet metal for the wheel wells was then formed over the tubing and welded in place for a perfect fit. Each of the aluminum panels is stiffened by an ample amount of aluminum ribbing formed by rolling it between two special little steel wheels.


Heat shield keeps hot air from engine compartment away from carburetors.

There is nothing new about acid dipping a body or a set of doors, but Wayne Gapp figured out some neat refinements that save a lot of preparation work when the car is being painted. For instance,if the outer surface is painted, the acid will be unable to work on it, a neat trick for preserving a smooth body finish. When a door painted on the outside is dipped, the outer skin is lightened from one side only. On the other hand, acid works on both sides of the unpainted door frame, lightening it up much more than the outer shell. Naturally,all of the door regulators are gone and the original glass is replaced by plexiglas.

A stock dash board represents quite a bit of weight to be neatly air chiseled out of the car. A and A Fiberglass in Atlanta supplied the replacement dash. A few well placed cuts allowed it to be titted into the rollbar cage. Once in place, it’s glassed right back in around the tubes. While they were at it, Bill Jamieson and Al Buckmaster proceeded to fabricate a removable instrument cluster that is attached to the dash with just a few cap screws. This is handy for reworking the wiring and also made it easier to install new water temperature and oil pressure gauges. Since the original firewall is much too thin and flexible, the pedal cluster is now mounted on a cross bar under the dash board and the small Airheart master cylinder is also hidden under the dash.This way, nothing bends or yields when Wayne Gapp steps on the clutch or brakes.

Lightening up the Maverick involved some major engineering projects such as fitting it with a much lighter Pinto rack and pinion steering. It mounts up front, out of the way of the headers, on its own separate cross members. Next comes the job of snaking the steering post with two “U”joints and a section of tubing next to the engine and through the small Oilite top bushing.

The front suspension consists of a pair of Monroe coil over shock units for which Gapp and Roush designed springs with the correct rates and heights. For the ultimate steering response, all rubber bushings in the lower control arm struts are replaced with ball joints. This firmly locates the suspension and prevents any changes in steering geometry, hence a more precise feel to the car. To add to this one piece feel, Wayne Gapp also provided a pair of tie-in bars from the chassis to the heads, as well as aluminum plates between the front of the engine and the frame. By the same token, a big welded bracket ties the battery to the right rear of the car.


Left; Loc Performance in Livonia, Michigan, machined a remarkable set of aluminum hubs for the Airheart front disc brakes. Right; Rubber bushings in the front struts are replaced by ball sockets for more complete “road feel”. 

The prime purpose of the Boss 429 heads, when they were first created, was to breathe more air than the Hemis and to win on circle tracks. The drag racers were to get what was left over from the circle track program(if it wasn’t planned that way, it was certainly the end result). Later, Wayne Gapp did a substantial amount of work on the 429 heads in an effort to endow them with some of the mid-range power needed to make the drag scene. The intake ports were certainly big enough but that didn’t keep the old style head from showing a loss of two tenths. Gapp and Roush cast up some inserts that reduce the cross section of the intake ports and at the same time raise them substantially. This increases the air velocity, improves the scrubbing and mixing action, and gives the incoming fuel/air mixture a better shot at the valves. Now the fuel arrives well-dispersed into the airstream, and ready to burn efficiently. Flow is increased, despite the fact that the intake ports are smaller.

The exhaust port was raised a good quarter of an inch from the original design, improving its output by nearly 20 percent! In fact, it now flows better than the one on the single overhead cammer 427 engine. Naturally, the valve sizes have changed, but that is all that Gapp and Roush are willing to say on the subject.


From 7000 rpm-on-up, this Monster 429 Boss seems to pull best with a set of 4500 Holleys mounted on a modest size plenum chamber, and a Weiand manifold

Manifold testing was almost as extensive as the cylinder head modification program, and you can’t very well divorce the manifold from the carburetors that sit on top of it. As Wayne Gapp explains it, individual runners are fine in theory, but even the Holley 4500 barrels are not quite big enough to feed the cylinders on a one-for-one basis for one venturi-per-port. By using a plenum chamber, or a big empty space between the intake stacks and the carburetors, you can get all of the carburetor’s barrels to contribute to each individual cylinder. Wayne Gapp adds that the Ford 429 heads flow more than the Hemis he has tested, and therefore benefit from extra intake manifold plenum size. Going a bit further, if you use the 660 Holleys which are smaller than the 4500’s, the plenum size should be increased. Latest finding is that the Boss 429 seems to pull harder in a high gear at 7000 to 8000 rpm with bigger carburetors and a small plenum.

The combustion chambers have been fully machined out to a Hemi shape and the TRW pistons are made to match. Even though big steel rods are used, the pistons call for a .060-inch deck clearance. Jack Roush tells us that running a slightlysmaller .050 clearance caused the pistons to hit the chambers fairly hard, something you can ill afford with the tender and expensive aluminum heads.


The heads are machined to a full Hemi configuration and the clearance between the head and pistons is held to .060-inch

You can get an idea of the stretching forces involved from the fact that these are NASCAR rods, bigger and stronger than anything else available for the engine.The clevite 77 bearings are pinned in the rods to insure against their spinning and the crank itself is a big steel job, also used for NASCAR circle track racing.

Since the Shotgun Express is low and close to the ground, the oil pan is shallow and thin in turn called for windage tray. Baffles welded into the oil pan trap the oil and take care of the slosh on takeoff. The pickup is placed down low and at the back to insure a good supply of oil, and to exclude air. Rather than beef the oil pump and throw off an excessive amount of oil around the crank, Wayne Gapp builds his engines with the stock pump. he does, however, block of the oil supply to the the lifter galleries which gives him more oil at the bearings and cuts down on the spray inside the crankcase. Credit for all the machine work goes to Vic Vocjec of Loc Performance in Livonia, Michigan.


Well-baffled oil pan has a rear pickup fed through a trap-door; low ground clearance makes for a shallow pan

Some people are just content to pour gas in the tank and turn the key, but the Gapp and Roush team goes a bit further, like first turning the tank sideways. This way the deep sie of the tank, original designed for clearance now catches the gas rushing backwards when the car initially accelerates. Add to this a Holley electric pump, mounted at the rear, near the bottom of the tank. The fuel fill for the tank is located inside the car, away from prying hands and gas cap collectors.

Incidentally, just buying Sunoco 260 is apparently also not enough, for it doesn’t always act the same at different meets or in different parts of the country. This leads to continous work with the spark timing. At 40 degrees, the engine becomes extremely sensitive, while 38 degrees spark advance is more acceptable but may not put out as much power.

Moving down the power train, you’ll find a Ford trans with a 2.54 First gear. To speed its removal for quick clutch changes, the aluminum floor pan is retained by Dzus fasteners. A substantially narrowed Dana 60 housing was ordered from Strange Engineering. Into it went all the care and detailing learned the hard way from breakage in the previous years. For instance, the tubes are not just cut down, but are new, thicker ones with larger flanges. Full safety hubs are used, same as the ones on the funny cars. Here the hub rides on large, tapered roller bearings, as big as the carrier bearings. This way, if an axle breaks, the wheel and hub can’t come off. Strange Engineering also adapts the Kelsey Hayes disc brakes to the housing and supplies the discs.


Left; The fuel tank is turned sideways bringing the large sump section towards the rear where it “gathers” fuel when the car blasts off the line. Right: Schiefer gears are fitted to a Strange Engineering spool assembly; note the fully-machined, steel retaining caps!

Incidentally, that axle taught us an good object lesson. Some primeval racer’s instinct in Jack Roush told him to not just bolt it into the care but to first take it apart for a good cleaning, and he found that it had been shipped dry. While he was at it, Roush also proceeded to LocTite the ring bolts to the spool. The original Dana retaining caps are replaced by fully machined steel caps. When the splines in the spool proved a bit tight for the axle splines, Strange shipped a magic little bottle of acid that cured the problem in seconds.

With the near narrowed to the point where it measures just 49 inches from flange to flange, the slicks fit well within the fenders and this in turn allows the care to be lowered. That’s no mean feat with Goodyear rubber that is 14 1/2 inches wide and 32 inches tall! The 15-inch wheels just barely clear the brake calipers, which definitely limits the placement of the balancing weights.

The rear suspension went through several transformations. At first, high hopes were pinned on an intriguing set of four link traction bars, but rather than spend half a season working out the details, they were quickly replaced by “known” leaf springs and more conventional bars. As Wayne puts it, “You can’t afford to fall in love with an idea, no matter how neat it looks.” Add a set of wheelie bars, and the Maverick is ready to rear up and go. ….A hard running well respected competitor from the Ford ranks!

Why Gapp & Roush were not factory supported

From time to time I see posts that talk about Gapp & Roush and how they were factory supported. Most people think that Gapp & Roush efforts were part of the epic support (engineering and direct dollar support) of racing that Ford supplied to teams in wide variety of sanctioning bodies during the 1960’s. I see comments about how Ford ‘commissioned’ Gapp & Roush cars.

This is emphatically not the case. Ford _never_ supplied dollar one of direct support. Were there parts that went out the back door? Yes…but that was in 1971. No later.

The 1972 Red Ford Maverick that Gapp & Roush campaigned had a ‘Ford’ symbol on the side. That was an effort to GET support from the factory but that support did not materialize. It did not materialize for ANY Ford drag racing operations whether that was Gapp & Roush, Bob Glidden or Don Nicholson.

When Ford shutdown most racing operations in November of 1970 and then exited NASCAR in 1971 my father was part of the shutdown.

It was this shutdown that led to his his decision to ‘walk the walk’ (he was telling racers what to do with the Boss 429 in Drag Racing and NASCAR) that led to Gapp & Roush moving into the open and campaigning the first Maverick.

Below is an article that was published in Motor Trend in February of 1971. It clearly tells the story of Ford Racing.



1 Ford Black Flags Racing

Ford Black Flags Racing

By Jim Brokaw
Appeared in Motor Trend – February 1971

The greatest peacetime non-governmental competitive effort to occur in this century has quietly drawn to a close — the victim of progress.

On November 20, 1970, Matthew S. McLaughlin, vice president, Sales Group, Ford Motor Company, announced that Ford was withdrawing from all forms of motorsports competition with the exception of limited drag racing and off-road support on a divisional and dealer level, effective immediately. This bland, antiseptic announcement by a subsidiary official marked the termination of a multi-million dollar effort by legions of determined and dedicated men to provide a tangible example of the might of American free enterprise.

Ford’s initial racing effort was undertaken back in 1901, by Henry Ford, to raise funds to build passenger cars; ironically, it is now withdrawing from racing in order to continue building cars on a profitable basis. The currently dissolved competitive effort was born of pride and the fight for a share of the marketplace in 1955. Ford had been the sole owner of a low priced V8 engine and the dominant marque in racing until rival Chevrolet took its new 8-cylinder engine to Fayetteville, N.C. on March 15, 1955, strapped it under Herb Thomas and won the race. Fonty Flock did it again two weeks later at Greenwood, S.C. in another V8 Chevy, and Ford’s exclusive fiefdom had been invaded. Campbell-Ewald, Chevy’s ad people, jumped on their two piddling NASCAR victories, the only two that year, and blew them up into the Second Coming. Chevrolet sales boomed and the freshly wounded Ford dealers bellowed.

Ford had not really been any more successful in NASCAR than Chevrolet; Oldsmobile, Hudson and Chrysler ruled the roost up to and through the 1955 season. Ford’s success was in other fields under other sanctioning bodies, and, outside of NASCAR, Ford had been the cheapest, fastest, most durable engine-body combination on the market. However, once Chevy started their publicity campaign, all the explanations in print couldn’t reverse the tide at the dealerships. It was obvious, even to the staid, precise Robert McNamara, Ford Divi- sion general manager, that a few victories were needed to reverse the trend.

McNamara called a “council of war” with his engineers. The decision was made to support the effort technically and financially from within, but to operate it through an outside concern. Peter DePaolo was selected to organize the operation from the outside. Buddy Shuman, A NASCAR cognoscente and sometime rum runner, was brought in from Charlotte to provide “field technical advice,” and Bill Benton, Ford’s field service manager for the Charlotte area, was named the initial company liaison man. DePaolo hired Curtis Turner and Joe Weatherly, two of the best in the business, to do the driving.

After a near spin, crash and burn on take-off (the first racing Fords couldn’t win a raffle in NASCAR), some corrective action was applied. Joe MacKay, special events man for the division, was put in charge of the program and John Holman, former truck driver for Bill Stroppe, Lincoln-Mercury’s man on the go, was put in charge of the Charlotte division of DePaolo Engineering; Ralph Moody and Fireball Roberts hired on as additional drivers. It worked.

2 JimClark 1965

Above: Jimmy Clark brought home the bacon at Indy in 1965. Ford’s first victory at the huge oval came after the stock car racing Wood Brothers had been called in to solve pit problems.

Taking the checkered flag 14 times in 1956 and 27 times in 1957, to Chevrolet’s 3 and 18, respectively, Ford’s race team gave the advertisers plenty of ammunition and the now affluent dealers in NASCAR territory were silenced.

But just as all the kinks were worked out and Ford’s well-oiled racing machine was thrashing along to a bright and lucrative future, the spectre of politics and the public welfare reared its ominous head. At the Automobile Manufacturers Association meeting in 1957, GM president Harlow Curtice proposed that the advertising of engine horsepower and performance figures be discontinued and that all factory support of racing be discontinued “in the public interest.” Since Ford was the only one then receiving any real sales benefit from racing and because the Ford engineers had been embarrassed by some of the weaknesses uncovered in the machines while under the stress of competition, the resolution passed and was accepted by all members of the AMA. In full compliance, McNamara ordered an immediate shutdown on Ford’s racing activities. Only the foresight and fortitude of two young men preserved the nucleus of what was later to be Ford’s best advertising and engineering stimulus.

Jacque Passino, who had transferred from sales promotion to take over special events when McKay resigned, and Lee lacocca, car marketing manager of the Ford division, each contributed a steel rivet of courage and wisdom to hold the basic racing machinery together.

Passino assured preservation of the hardware by maneuvering the sale of the equipment in the direction of John Holman. He argued for the retention of the best brains in the operation by recommending the addition of Jim Travers, Frank Coons, Danny Eames, Fran Hernandez and Holman to the company payroll. Eames and Hernandez made the list.

Eames is currently the director of the Autolite performance program and Hernandez managed this year’s successful assault on the Trans-Am championship. Travers and Coon formed Traco engineering. John Holman formed a partnership with his driver-mechanic, Ralph Moody.

3 Lemans 1966

Above: Ford’s finest hour, and most expensive one, came at Le Mans in 1966 with a three car parade across the finish line. Bruce McLaren (2), Ken Miles (1), and Dick Hutcherson (5) driving

Iacocca argued vigorously but unsuccessfully in the face of corporate resolve for the retention of the racing parts in the Ford catalog. In spite of his failure, Iacocca knew what sold cars to young people in those days and he knew, as did anyone who bothered to note the birth statistics from 1946 on, who was very shortly going to engulf the car buying market, a veritable army of young, aggressive potential customers.

Ford outsold Chevrolet in 1957, but fell back to second place in 1958. There is no empirical data to tie the sales figures to Ford’s racing participation and success, but the coincidence is there. General Motors, meanwhile, went at it hot and heavy. Using spinoff parts from their high performance Corvette on other models, Chevy built a formidable racing machine. In 1958 Chevy won 23 races to Ford’s 16. 1959 was worse, with Ford winning 8 races to Chevrolet’s 14.

In spite of the no-racing edict, pride and an incurable itch motivated Don Frey, executive engineer for Division product planning, to do something, how ever small, to get Ford back in front on the track. In 1959 he called Dave Evans, Don Sullivan and John Cowley together in his office getting the ready for next delivery. He suggested that they pool their talents to come up with a “better idea” for the ailing Fords. With clandestine assistance promised from Bill Innes in Engine and Foundry, the intrepid trio set out with great zeal and little else.

Next, several events took place which were to profoundly influence Ford’s vow of abstinence. In February 1959, Daytona’s new superspeedway hosted its inaugural race. During 1960, Charlotte and Atlanta also spawned new superspeedways. There were now four supertracks, including Darlington, running eight events per year at speeds that defied credulity. The public, with a built-in psychological barrier of 100 mph, was now aware of NASCAR, and very much interested in it — particularly the young people.

In late 1960 McNamara was elevated to the presidency of the corporation. Lee lacocca filled the vacancy as division General Manager. Three months later, McNamara was called to Washington to serve as Secretary of Defense and lacocca was able to take some corrective action to recapture the youth market from Chevrolet and Pontiac, both of which were doing their thing at the track and were much in demand with the young bucks.

Under Lee’s guidance and direction, Ford started building some competitive hardware. With the new 390 c.i. engine as the great blue hope, Ford started slipping some aid out the back door. The motley was scrounged out of other projects for some very limited support.

The limited help paid off. In 1961, Ford started modestly back, winning seven NASCAR races, including Atlanta, Charlotte and two at Darlington — all major tracks hosting expansive crowds who went away drawling words of Ford’s new high speed efforts.

Ford officially abrogated the A M A non-aggression pact in June 1962 and launched an ad campaign hawking the Fairlane and Falcon as “the lively ones from Ford.” As Passino said, it was advertising only, but there were better days ahead. Ford made the initial penetration in the drag racing world, then tied up with Carroll Shelby and his Cobras. In 1963 they set their sights on Indy to tout their new small block engine, selecting Colin Chapman and Dan Gurney as the men to do that job. They very nearly won it on the first try with Jim Clark at the wheel of one of Chapman’s Lotus’, setting a pattern that would be repeated time and again in competitive arenas: because of faulty detail planning, Ford would almost win a major race. In succeeding attempts, they would eventually triumph but the dollar overkill required would alienate the very people they were trying to win over.

By 1964, the entire race program needed tighter control and coordination. Leo Beebe was given the job as manager of the new Special Vehicles Department. His task was simple: win at Indianapolis, Daytona and LeMans. He proceeded by kicking out all the non-racing activities and passing them over to Sales Promotion. He then installed Passino as his number two man and divided the assignments. Dave Evans had the Indy projects, John Cowley got stock cars and Ray Geddes was assigned the joyous task of winning at LeMans.

4 Passino

Above: Jacque Passino, stern, silent, unsmiling, was vital driving force for Ford’s racing efforts in the sizzling sixties.

In spite of the remarkable progress, success was not achieved without penalties or problems. Millions were wasted at Indy when races which should have been won were frittered away by poor pit work, improper selection of tires and the bad luck of driving in spilled oil. Lives lost in 1964 included Dave MacDonald at Indy, Fireball Roberts at Charlotte and Bobby Marshman at Phoenix.

The ultimate success of the Ford effort is well recorded legend. Indy was captured by Jimmy Clark in 1965 and LeMans fell victim in 1966, but not without some disappointments and a bit of personnel reshuffling. After what had started out as so promising in 1965 ended in abject failure, Ray Geddes was replaced by John Cowley, with Homer Perry as his assistant. Renewed efforts and perseverance paid off in the triumphant parade of three Fords across the finish line at LeMans in 1966.

Once the red Ferraris had been put in their place, Beebe left the Special Vehicles Division to become general manager of Lincoln-Mercury and Passino took over as manager of SVD at the end of the 1966 season. Success followed on success, with a second victory at LeMans in 1967 and an incredible follow-up win in 1968, by a John Wyer GT-40.

Ford dominated NASCAR from 1963 on. With the exception of the partial pullout in 1966 and Richard Petty’s great string of victories in 1967 (for MoPar), it has been very much a Ford show. Indy has been Ford country since 1965, with occasional spurts by Offy to keep it all interesting. The racing world had a Ford fence around it until the 1970 season.

Racing had been an expensive proposition for Ford. Speculation bracketed the 1967 budget at $17 to $30 million. The exact figures aren’t available but a little deductive reasoning can put a lot of numbers into their respective slots. LeMans in 1967 had to run close to $7 million. The stock car program devoured another huge share, with engines at close to $5,000 each and a race ready stocker weighing in at $22,000, just to start off; add in a backup car for each team, special cars for outside drivers, at least one to two new engines per car per race, travel accommodations, entertainment for guests, plus miscellaneous incidentals, and it’s not that difficult to consume two to three million dollars in a full season. Even the abortive 1968 Can-Am effort was capable of eating up seven figures. The early Indy project consumed the green at the rate of $32,000 per engine, and even when Ford sold the dohc’s to outsiders, they took a $15,000 bath in order to make the price competitive with Offy. Since many engineering refinements came out of the race program and the publicity value of most of the programs was beyond calculation, all or most of the cost could be justified.

The act which inadvertently sealed the doom of Ford’s racing activities transpired when Don Frey moved from marketing to engineering in 1967. Since Don was an avid supporter of racing, he moved the Special Vehicle Department to engineering with him. At the time it was a wise move; it later proved fatal.

The same youth market which was the target of the performance program turned away from performance machinery. Imports ate a huge hole in the market in the late sixties, so Ford had to counter with a small car of their own. The task of developing the Maverick and Pinto consumed huge amounts of engineering funds. Smog regulations required more research and development support out of engineering funds. Racing had heavy competition for the dollars.

Marketing expenditures are fairly flexible. The target can be measured in numbers of people exposed to the product per dollar spent. With 53 million people watching racing in person and as many as 53 million more watching a single event on TV, the cause can be argued. However, when there is a fixed amount for engineering R & D, the mandatory items come first.

5 nascar

Above: End of an era. David Pearson (17), Gale Yarborough (21), Lee Roy Yarbrough (98) and Donnie Allison (27), Ford’s last racing team, in rare group shot, followed by now outlawed Superbird

Imports cut out the first piece and smog took the next one. Then the very thing that was created by research ate further into the available funds. The profit margin on a subcompact Maverick is considerably less than that on a loaded Torino or Mach I Mustang. Sales increased, but profit margins decreased. Less income, less allocation to R&D. The gun was already pointed at the head of racing.

In 1969 the government launched its safety crusade in earnest. Law after law poured out of Congress demanding improvements, with minimal lead times permitted. Every proposal that even came up before Congress and every standard that the Department of Transportation even considered demanded research and testing evaluation, even before it could be determined whether or not the proposal was feasible.

In 1969, Henry Ford II pledged the assets of the company to help whip the environmental pollution problem. He wasn’t fooling. Very shortly after his speech, Ford announced the allocation of $18 million for the installation of antismoke equipment on the factories’ smoke stacks. Two months later, the racing budget for 1970 was drastically reduced, by about 75 percent.

The response of the Ford NASCAR teams had no small influence on the final decision to pull out completely in 1971. Instead of tightening their belts and making all major races in order to keep Ford in the thick of the fight fight, many racers backed off and bypassed some of the mid-season events. This, of course, is good business: don’t run on your own money; wait till you can promote some outside sponsorship.

As a necessary corollary to the termination of the race program, Ford initiated a complete audit of their former subcontractors’ books. The mere act of investigation generates suspicion and attendant rumors. While none of the myriad stories currently traversing the whisper circuit have been confirmed, one incident of note can be verified. After having perused the books at Kar Kraft, the auditors planned an inventory check. Before this could be accomplished, the Ford employees who normally labor at one of the Kar Kraft facilities arrived at work to discover themselves locked out. Unwilling to breach the padlocks, they returned to Ford territory and were reassigned to more stable environs. The auditors are still pacing the floor.

With about $362 worth of Washington-inspired improvements riding on each car, and the promise of more oozing out of the Department of Transportation weekly, racing was headed for the chopping block. Since only a portion of the increase can be passed on to the customer, the rest has to come out of the corporate hide.

It must have been a painful ordeal for the men who gave the whole program its impetus to have to administer the bullet in the brain. Lee lacocca, newly appointed president of the com- pany, hung his career on the line 10 years ago for it; Bill Innes, North American operations boss, snuck engine parts out the back door; Don Frey, manufacturing group leader, started the first secret racing group. They have responded to a greater responsibility.

The men who made it work are largely in a state of shock, presiding over the carving up of their competition pie. Jacque Passino, a racing director without a racing program, declared himself surplus and resigned the day before Thanksgiving. Hank “Horsepower” Gregorich is the new manager of the Special Vehicles program, consisting of the three clinics and very little else; Homer Perry has the public relations test cars; Charley Gray is phasing out the NASCAR operation. John Cowley will be busy counting the racing beans during the 60-day phase out; Fran Hernandez is probably trying to get Parnelli’s winning Mustang cast in bronze.

It is ironic that the source of virtually all of the significant safety development in the last 15 years has been aced out by a government stimulated safety program. Perhaps there is still somebody in Dearborn who could point this out instructively to the Muskie-Nader complex.

Interesting Factoid about Wayne Gapp in National Dragster

From an article in Feb 5th, 1999 issue of National Dragster:

“In final round appearances during the 1973-1975 seasons, the most dominant Ford in Pro Stock was not driven by Bob Glidden but by Wayne Gapp. The Livonia, MI.-based racer appeared in 16 final round rounds to Glidden’s 12 during that period, winning six of them and the 1973 World Championship crown.

In fact, Gapp had more final-round showings in those years, outdistancing luminaries Bill Jenkins and Don Nicholson, who had six and three appearances, respectively.”

I did not know that.

Gapp and Roush get a new car…and driver.

Been awhile since I posted. Almost two months. Busy, busy, busy.

Here’s a bit of information that I got from the Facebook Nostalgia Pro Stock group (via Dan Williams via Angel Cordero). It comes from the December 1976 issue of Car Craft’s ‘Straight Scoop’ column.

The Gapp and Roush Pro Stock team has several new acquisitions. First is the 1977 Pinto, complete with the aerodynamic shovel nose, for use in the new season. And to go along with the new car, they have a new operator: Ken Dondero, formerly associated with Dyno Don and Team Jenkins, has replaced Wayne behind the wheel. With both Gapp and Roush free to concentrate on engine development, and with the possibility of a less punitive weight break next season, the blue and white Pinto may reappear in the winner’s circle.

CarCraft StraightScoop 12 76 copy

Bossing the 351

Every now and then, when I have a bit of time, I like to post old articles about some topics relevant to this site. In this case an article from the February 1971 issue of Hot Rod magazine that discusses the Boss 351 Mustang

Pg 1 image 1

Bossing the 351

By Steve Kelly

Ford Division’s Boss 351 is some kind of quick machine. Why and how the 351 Cleveland engine responds to being “bossed” is something we’ll discuss a few lines from now. But the production-line car is a matter well worth mentioning right here.

The Boss 302 is no more, at least in a production version. Like Chevrolet, Ford has found it costly and no longer necessary to build an engine to the exact size as that specified for the SCCA Trans-Am series. SCCA doesn’t require an engine to start life as a 5-liter nowadays. It can be de-stroked to meet the limit. Ford’s 302 T-A engine had a 3.00-inch stroke, and thd 351 carries a 8.5-inch arm. That 302 Boss engine wasn’t exactly cheap to produce, but the 351 Cleveland engine is an assembly-line operation, and the Boss small block parts have been redesigned to fit. Unlike Chevrolet, their enlarged sedan racing engine runs better than its earlier and smaller counterpart. When we ran the ’70 Z/28 Camaro, it wouldn’t even come near the times the ’68-69 302 Zs produced. Of course the car was different, but the ’71 Mustang is a lot different from the ’70 model. Not only is it two inches longer and wider, it is close to 150 pounds heavier. Without changing it from street-legal trim, the ’71 Boss 351 laid down a 14.09-second elapsed time at Orange County Raceway, with a speed of 1O2.78 mph. This is the same track the ’70 302 was driven over, and its best pass was 14.621 seconds with a speed of 97.5O mph. That car had a 3.91:1 limited-slip rear axle gear, just like the ’71 car, and we had to wire around the factory-installed rpm limiter to achieve that 14.621 time. With the rpm limiter removed from the Boss 851, we raised shift points to 6500 rpm for the best e.t. of 13.800 seconds and a speed of 104.82 mph. Previous to this, shifts were made at 6000 rpm. We, meaning all who drove the car that day, were impressed. But just so the story doesn’t get too romantic you should know that the car had been spending some time at Bill Stroppe’s shop in Long Beach before it was sent out on the road. While there it had been fitted with rear traction bars, a new clutch (stock type) and a set of Dough Thorley headers. We can’t vouch positiviely one way or the other as to the engine’s internal integrity, but externally, all was as it should be on a production car. Jetting hadn’t been increased, and this became evident when low-speed full-throttle stars were tried. THe engine stumbled upon transition from primary to secondary throttle opening, and during primary operation on the Autolite air-valve carburetor, the engine wanted always to run a shade on the lean side. We’re certainly not pointing any accusing fingers at this car, but we do like to keep the record straight and everyone informed. While it surely did have a good tune-up job applied, there’s no doubt that addition of headers contributed to the 351’s performance. Better rear spring tie-downs could’ve been used because wheel hop was still evident when leaving the line. After our stock test of the ’70 302 Boss, we added headers and a 4.80 Detroit Locker rear gear. After much tuning and gnashing of knuckles, the 802 put in a best performance of 13.84 seconds with a top end of 108.44 mph – this with shift points at 7200 rpm. When the headers were allowed to exit exhaust gases sans muffler restriction on the 351 Boss, it cranked out consistent 13.6 e.t’s and ran a best of 13.58. The car also registered a half-dozen 107-plus mph speeds. There was no need to go beyond 6500 rpm in each gear. A 4.90 gear would really set the car down into the low l3-second region, but unfortunately, that ratio isn’t factory-available this year. According to Ford literature, a 3.91:1 Traction-Lok is standard, and no other number is available. But there are plenty of gear cutters in the business, so it isn’t any great problem to make a change.

Now the Boss 351 is an inspiring super-car, and even though it does have a horsepower-to-weight factor over 10-to-1, insurance companies are well aware of its threat to peaceful underwriting. Insurance notwithstanding, there’s no reason everyone should buy a Boss 351. Any 351 Cleveland engine can be converted into a Boss. Maybe some people don’t like the ’71 car. It doesn’t matter. As good as the news is about how well this small-block Ford runs, the fact that Ford has outlined a way of updating early-model Cleveland engines to current standards is more appealing. Along with parts development, a new catalog entitled “Staging The Cleveland” has been published, with all kinds of inside information and parts numbers. Ford and Autolite dealers should have it by now. Incidentally, Autosport Products, Inc., who market the Shelby line, have also developed a number of aftermarket pieces for the 351-C.

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ABOVE – Exterior of Boss 351 differs little from 302 except that water pump housing is semi-integral with block. Cleveland engine has flat plate bolt-on pump cover, while 302 is complete item by itself. Ram-Air is standard. New Fords have resistor plugs and return springs in throttle cable.

BELOW – Stock high-dome Cleveland piston can be replaced by Boss level slug with higher top and valve reliefs cut full length of dome.
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The Special Vehicles Program men at Ford began their development way last year, and based their work around a 351-C-engined Mach I. It carried a wide-ratio four-speed, 3.50:1 Traction-Lok axle. Ram-Air hood scoop and F70-14 tires. As received, in stock form, the Mach I ran 15.09 seconds elapsed time with a speed of 94.52 mph. Traction bars were installed because of wheel hop, and an Autolite dual-point conversion kit (DIAZ-12A132-A) added because of high-rpm point bounce. It then ran a 14.75 e .t. and speed of 95.37 mph. First-stage work, as outlined in the Autolite manual, was begun from this point. A four-barrel aluminum intake manifold (DIZZ-9424-G) and 780 dm rated Holley carb (DOOZ-9510-R) was substituted, the resultant performance being 14.55 seconds elapsed time and a speed of 96.30 mph. This Holley four-barrel is the same one that’s used on 429 Super Cobra Jet Fords. After this, a hydraulic camshaft (DIZZ-6250- A) with the same specs as the 428 C-J hydraulic stick was selected. Use of this cam raises torque peak by 600 rpm, and is worth 29 additional horsepower over a two-barrel 351-C cam. Valve lift is A81-inch intake, A90-inch exhaust, with 270-degree intake duration and 290 degrees on the exhaust. Stock rocker arms can be retained, but new valve springs (C90Z-6513-E) with higher tension and inner dampeners are required. Also needed are new retainers. (DOAZ-6514-A), and sintered iron fulcrums (DOOZ-6A528-A). If the work is being done on a four-barrel 351-C, the retainers and fulcrums don’t need replacing. This cam presents no problem when used with an automatic transmission. Performance gain on the “mule” Mustang in Dearborn using this camshaft was significant. Elapsed time dropped to 14.26 seconds, and speed jumped to 99.03 mph. The fifth step taken involved tubular exhaust headers. Autolite-Ford doesn’t offer this item, but there’s no shortage of availability elsewhere. A set of Doug Thorley 1 7/8-inch-by-34-inch long tube headers helped the ’70 Cleveland-engined car drop its elapsed time to 14.08 seconds and got speed up to 100.23 mph. With all this accomplished, our heroes back at Ford slipped in a 3.91:1 rear axle assembly (C80Z-4209-A). The Traction-Lok torque-sensitive limited slip was retained with this lower ratio. By adding the gear, elapsed time dropped to 13.08 seconds, and speed went up to 102.63 mph. Final change to this test subject involved slipping in a Boss mechanical cam (DIZZ-6250-B). There’s more to it than just the cam. Actually, this seventh operation is considered the “Dominator Kit.” To complete it, the following items have to be included: DOAZ-6500-C 302 Boss solid lifters; DOZZ-6507 -A intake valves; DOZZ-6505-A exhaust valves, C9ZZ- 6518-A keepers; C9ZZ-6564-A rocker arms (only if converting from a two-barrel engine, or if four-barrel rockers indicate replacement is necessary); C9ZZ-6A527-A 302 threaded rocker arm studs; C9ZZ-6A528-A cylindrical sled rocker arm fulcrums; C8SZ-6A529-A 7/w-inch rocker stud nuts; C9ZZ-6A29-B %(i-inch rocker stud jam nuts; C9ZZ-6A564-A guide plates; and DOOZ-6565-B hardened pushrods which come from the 429 SCJ parts bin. This takes care of most of the parts, but because the 351 Cleveland engine is normally only equipped with a hydraulic cam, the engine has no provision for valve lash adjustment. It is “possible” to get away with using adjustable pushrods, but in some cases the pushrod-to-rocker interference is such that the adjustment end has to be placed down. This means the topside of the motor has to be dismantled to adjust the valves! In addition, rpm limit is around 6000 with adjustable pushrods, and that doesn’t allow full utilization of the mechanical cam.
So to do the job right, head modification or replacement is the answer. Using four-barrel heads from a 351-C, 0.300-inch must be milled from each pedestal, and this requires an alert machinist because the surface of each pedestal is not parallel to the head surface, due to the canted valve angle of 351-C engines.

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ABOVE – When you get to the Boss-level Cleveland engine, your V8 has canted valves, stamped rockers, H-D fulcrums, guide plates, mechanical cam with adjustment capability and super-smooth valve ports.

BELOW – Ford now uses Autolite “air-valve” 750-cfm 4-bbl on big engines (right), which is an evolution from the earlier 4300 series 4-bbl (left).
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When the milling is done, the original stud holes must be drilled .088-inch deeper (use drill size .376-.372-inch in diameter) and tapped 7/16-14 UNC thread. Then the 302 studs will go right in, and when this route is taken, use 428 valve springs (C90Z-6513-E) and 429 retainers (DOOZ-6514-A). The other method of obtaining valve adjustment is to swap over to Boss 302 heads. But this calls for some machine work too. The Cleveland engine routes water to the head via an internal passage that feeds the head. The 302 heads were made so that water is fed in from the manifold. them is fairly easy. Place a 351-C on a Boss 302 head and scribe or dykem-mark the spot where the water must be. It’s in front corner. Then drill at this using an l1A6-inch bit. A drill is suggested; a hand drill would wear out the operator. There’s still a water open on the top of the 302 so a 351-C inlet manifold has to be used; and since it has no water provision, it will seal off the 302 port(s). Head gaskets from a 351-C four-barrel (D0AZ-6051-C) are required. When Boss 302 heads are used, 302 valve springs (D0ZZ-6513-A), spring seats (C9ZZ-GA536-A) and retainers (C9ZZ-6514-A) are also to be used.

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ABOVE – New-style Mustang doesn’t handle as well as its ’70 version. but in Boss form it can hardly be called a slouch. This one came without an abundance of add-ons, which weren’t missed.

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ABOVE – Muscular Fords feature Traction-Lok differential that is a spring-loaded clutch pack unit. It feels a lot like a ratchet-type limited slip,and doesn’t cost extra on Boss 351s.

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ABOVE – Cleveland built Boss blocks start life with four-bolt main bearing caps. Even though production bearings work fine for most applications, premium main and rod bearings with tin-babbit overplate called 351-C “GT,” are available through Autolite-Ford.

Now that the Boss 351 is a item, simply substituting these heads on a conventional Cleveland engine involves no machine work, but they’ll be somewhat rare for a few months, and not as cheap as performing surgery on the cylinder heads outlined above. When going to the “Boss” stage, it’s wise to increase carburetor size. Autolite-Ford recommends an 850-cfm unit such as a Holley R-4781-AAA. This is a dual-pumper unit, and initial jetting should be No. 80 on both primary and secondary sides. At this point, the basic Cleveland engine is identical to a Boss 351 in all respects save for four-bolt mains. Even these can be had from speed equipment manufacturers. The Ford crew retained the Cleveland heads on their car, and with everything buttoned up, it ran 13.80 seconds e.t. and a speed of 104.02 mph. By the way, all runs at each stage were made with street tires mounted and with exhaust system capped up. In other words, they equaled the times of our ’71 Boss 351. This Cleveland-design engine is a “clean”-burning powerplant. Ford wouldn’t release actual figures on emission counts, but the Boss 351 is able to pass established emission levels without the aid of a thermactor (air pump), despite its having features that traditionally hinder low smog readings. Our test Boss didn’t get overly thirsty on fuel either, reaching a “high” of 14.50 mpg and a low of 11.58 miles per gallon. The ’70 Boss Mustang handled better than this one, perhaps because it didn’t have an Autolite four-barrel that starved out halfway through a hard corner. Ford now installs, at extra cost, the Saginaw variable-ratio steering, and we can’t say it works as well on the Mustang as it does on the Camaro. The Camaro has its steering linkage mounted ahead of the front crossmember, and the variable ratio serves more to bring the steering back to neutral than anything else. But the Mustang has its steering linkage behind the crossmember, and the variable-ratio unit induces a sometimes “shaky” oversteer. It might be okay for matrons in LTDs with bedspring suspension, but the Boss 351 doesn’t need it.

The ’71 Mustang is a long way from that refined Falcon-based Mustang we all gaped at in 1964, and for that, present Mustang owners can be happy. This one feels like it’s taking on the size of a Torino (in some ways it but no matter what its shape or size may resemble it sure runs like a racer. The Boss 351 is going to salt away a few Z/28’s before its season is up.

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ABOVE – Boss heads have minimal shrouding around valves and good exhaust. 302-design head chambers measure 58.5cc on the 351, but hydraulic stick, 302 heads aren’t necessary.

BELOW – All these parts are needed for cam conversion.
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  1. CARBURETION..Autolite4-bbl spread-bore, 750cfm.1.565-in.-dia. primary bores,1.690- in.secondary bore dia.
  2. VALVE TRAIN…Mechanical lifters, .022-in. lash. 1.73:1 rocker arm ratio; 2.195-in. intake valve dia.,L.7L4-in.exhaust..491-in. lift, intake & exh. int. opens 50 degrees BTC, closes 94 degrees ABC; exhaust opens 102 degrees BBC, closes 42 degrees ATC. 324 degrees duration, intake & exhaust
  3. DRIVETRAIN,..4-speed all-synchro transmission, 1st gear, 2.78:1, 2nd, 1.93:1; 3rd, 1.36:1, 4th,1.00:1 Semi-centrifugal single disc, 11.0-in.-o.d clutch, 1845-lb. spring load Traction-Loc-equipped 3.91:1 rear gear, 9.0-inch-o.d.ring gear
  4. BRAKES…Front disc/rear drum with Bendix integral power assist 11.3-in-o.d.cast iron disc; 10.0-in.-dia.rear drum, 185.1-sq.-in. effective lining area
  5. WHEELS & TIRES..15- x 7.0-in. steel, “zero offset” wheels; F60-15 Goodyear polyglas tires. 4.5-in.bolt circle, .50-in.-dia. lug studs
  6. SUSPENSION…Front: Independent single lateral arms with drag strut. 130-lb.-per-in. wheel rate, coil spring mounted over upper arm. 1.18-in.-dia piston tube shocks; .85-in.- dia. stabilizer bar. Rear:Semi-elliptical 53 x 2.5-in. rear leaf springs, 134-lb.-per-in. rate at wheel 1.18-in.piston dia. tube shocks, staggered .50-in.-dia. stabilizer bar
  7. STEERING…Saginaw integral power-assisted with variable ratio. 16.0:1 constant gear ratio; 20.2:1 constant overall ratio. 3.40 turns lock to lock. 15.0-in.-dia wheel. 39.8 ft. turning dia., curb to curb
  8. PERF0RMANCE. Quarter-mile(best):13.589 sec., 107.52 mph
  9. DIMENSIONS.. Wheelbase: 109.0in.; front track:61.5in.; reartrack:61.0in; over- all height:50:1in.; overall width:74.1in.; overall length:189.5in.; test weight:3625 lb.; body/frame construction; unitized; fuel tank capacity:20gal

Wayne Gapp builds a Hi-Port-Boss-429

Wayne Gapp Builds A
Hi-Port-2-Plug Boss 429

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The first part of this season was spent by Wayne Gapp, Jack Roush, Al Buckmaster, and Bill Jameson in getting their Maverick to go and handle properly for Pro Competition. When the combinations were pretty much figured out , the team went out and splurged on a magnificent paint job in metallic blue and gold. At the AHRA Nationals, both plans paid off, as the Maverick was top qualifier at 9.75, and was chosen as the best appearing car of the event.

Wayne Gapp and three other Ford engineers with heads-up racing experience combined to figure out why Ford’s Boss 429 breathes so asthmaticallay, and then applied their solutions to a winningly prepared Maverick race car.

Story and photos by Alex Walordy

DEARBORN IS FAMOUS for two Ford shops. One is slightly bigger than the other. The first is owned by the man whose name is on the front door, and the second one, located on Outer Drive in a small garage belongs to Wayne Gapp and Jack Roush. Both are engineers and both have raced longer than they care to remember. Teamed up with the Gapp and Roush Racing Enterprises are Al Buckmaster and Bill Jameson, also engineers and racers, and also successful at both occupations. Bill’s strongpoint is making special pieces while Al Buckmaster is an expert at flow testing heads and manifolds.

Naturally, a team needs a starting point, and the Maverick turns out to be the lightest car on the market with the smallest wheel base acceptable for Pro Stock use-103 inches, which tops the 100 inch lower limit. In fact, Gapp and Roush succeeded in holding the 7 pounds per cubic inch weight as well as the correct Pro Stock weight distribution without having to go to acid dipping. Hours of cutting and swiss cheese drilling replaced the cubic money needed for dipping. While the window glass is still there to meet the rules, non functional pieces such as window regulators are now a thing of the past.

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Maverick interior uses Solar seats, skinny steering post, Moon tach and S-W gages, bright white wheel and raised custom Hurst custom shifter. The entire dash comes out after removing four screws.

To make room for the Boss 429 all suspension points had to be moved two inches further out. Then, to keep the front wheels from going “TILT” on take-off or during the run, the boys did a series of checks, moving the suspension through its travel range with the front springs and shocks out of the way. Slotting the suspension mounting holes helped in finding the correct locations. Washers which form part of the mounts were then welded in place, covering up the slots, to permanently locate the pivots. Some strange things had to be done to the lower control arm struts such as making hinges and pivots to replace the usual rubber bushings. Also, the drag link was lengthened a couple of inches and the standard Maverick steering gear gave way to an exotic right hand drive gear ordered from Ford of England. The advantage is that it fits on the outside of the frame and doesn’t interfere with the engine. Originally, the spring towers were turned 180 degrees to get them out of the way, but changing springs and shocks became a hassle, what with removing the fender each time. Now there is a set of shallow towers with caps that accept the special front shocks. Those shocks are used not only for damping but also to limit the front end travel. Adding space bushings between the shock and the tower or switching to a shock with a shortened rod limits the lift at the nose of the car. The general idea is to have the front end lift quickly for good initial weight transfer and then settle back down so that the car will be low and stable during the run.

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Dave Landrith, of the Landrith Corporation, gets credit for an interesting rear suspension that departs from the traction bar route and achieves full control with springs and shocks alone, in Mopar fashion. The spring eyes are now closer to the axle housing. There is also more metal in the front of the spring all of which combines to make it act like a traction bar. New support plates welded to the floor pan at the torque boxes(just in front of the rear wheels) have a series of holes for mounting the springs higher or lower. This controls the amount of lift or squat that you get out of the suspension on takeoff.

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Big tires call for more room at the rear wheel housings and this in turn made it necessary to move the springs closer to- gether. Next thing you know, Gapp and Roush were narrowing the gas tank, which brought several fringe benefits such as better control of the fuel slosh and a small weight savings.

A suspension will not work unless the car is stiff enough to back up all the pivot point locations. By the time Bill Jameson was through heliarcing, the Maverick acquired not only a roll bar but also a bridge like structure that extends back to the rear spring shackles. Add to this a crossmember that forms a drive shaft loop and ties into the roll bar cage as well as to the torque boxes in the floor. The extra weight proved beneficial to both safety and traction.

The Ford racing program generally alternated between lavish spending and penny pinching. As far as the Boss 429 engine was concerned,the spending went to NASCAR, while the slimmer pickings made their way to the drag strip. Then came a series of last minute attempts to make the 429 perform on a strip-a dollar short, an hour late. The 429 Boss went out of production back in 1970 but, there are still enough of them around to put quite a dent in drag racing circles and Wayne feels that it could be superior to the existing cammers both in power and in durability. In fact Gapp and Roush now have a back log of orders for ihose engines, having proved them at the strip.

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The original Boss 429 engine was designed for Daytona and destined to go under the low hood line of the Talladega. As a result the huge ports have a very low entry point and must swing through a 90 degree angle to connect with a valve. This results in uneven fuel distribution and costs horsepower. The trick is to straighten out the flow then give it a more direct shot from the intake manifold to the valve, In effect, the entrance of the port must be raised to straighten the flow.

Wayne Gapp hit on the idea of installing some crescent shaped cast aluminum inserts that raise the level at the floor of the ports. Raising the roof of the port to retain the round cross section then breaks through to the outside, and additional inserts are needed there too. The inserts are retained with an epoxy bond as well as by Allen screws. The result is a port height that reaches almost to the level of the rocker arm covers. While the port diameter is a little smaller than before, 2 1/8″ instead of 2 3/8, they flow just as much as the original NASCAR head on the flow bench. Even better, the smaller crosssection area and the higher velocity of the air fuel mixture coming through results in much higher mid-range and improved response at the drag strip. The dyno says twenty horsepower and the ET slips at the strip show that the change is worth between one and two-tenths.

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Boss 429 combustion chambers stop just sort of having a full hemi shape. Two small pulled-in quench areas (which gave rise to the “Blue Crescent” name) proved to be a nice conversation piece most beneficial in coping with NASCAR rules. However drag racers look for more compression than long haul circle track burners and had a hard time fitting a high dome piston to this tricky shape. Wayne Gapp machines the combustion chambers to a hemi shape, removing the two side sections. He also made matching tooling to cut pistons, and is able to get close clearances and high compression.

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Two high compression Boss pistons are available. The quench one with the two side steps carries part #C9AX6110B. The hemi piston carries part #C9AX6110BH. Valve pockets for those pistons depend not only on cam overlap and decking but also how deeply you can sink the valve into the head. This treads with a heavy step on many standard ideas that drag racers have, but Wayne prefers to bring the valve further into the head, which allows him to keep a smoother piston contour. He then provides ample relief around the valve, blending the seat with the combustion chamber walls in smooth tulip shape and actually gains flow rather than losing any.

If you happen to have a street Boss as opposed to the NASCAR job, all of the modifications still apply, In fact, both heads are machined from the same basic casting. Exhaust valves on both engines measure 1.7 inches and there is a 1/8 inch difference between the 2.25 street valve and the 2.37 Boss valve. By the time Gapp and Roush get through with the seat inserts on the aluminum head, they blend in a wider radius for the larger valve, remove the casting burrs from the stock port and gain another 25 horses.

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Theory has it that the centrally located spark plug is the very best you can get. Unfortunately this conflicts with the valves and so Wayne Gapp, just like his Mopar counterparts has gone in search of two plugs per cylinder. A tremendous amount of work is involved including new spark plug wells that are heliarced to the rocker covers and seat against the heads. So far, there is only one set in existence and they haven’t been tested enough to make the next move.

The manifolding choice has narrowed down to a Weiand intake topped by a small size plenum or open chamber under the carburetors. Tests with an independent runner system were unsatisfactory and even the Mopar boys seem to have departed from this since Gainesville. To gain a little extra cooling, the bottom of the manifold has been sealed.

Three types of rods with different lengths were used on a 429 Boss. The early street series were 6.55 inches long. They were good, durable, but too short for high compression pistons. The production rod was 6.60 inches long, center to center. Best one of the lot was the 6.785 inch NASCAR rod which is longer, stronger and expensive. It is built for bullet proof performance during a 500 mile race, but most drag racers prefer lighter and less expensive aluminum rods. You will need 0.660 deck clearance with an aluminum rod as opposed to .040 inches on steel rods. Either way, clearances should be cross-checked by claying up the top of the pistons.

The rest of the bottom end includes a street type of Boss crank with grooved mains and a blocked off oil supply to the lifter galleries. Wayne Gapp suggested not blocking the special pressure relief spring in the double entry oil pump. On a cold start, you can coil bind the spring, raise the pressure to 300 psi and blow the oil filter clear off the engine.

The cam is a PPX 6250Dl-4 available through either Holman and Moody or Gapp and Roush. This cam will be released shortly through Ford dealers under Part #DLZX6250-EA. You have a choice of rocker arms. The stock one can be used providing you lighten it up and replace the lock nut and adjusting screw with the hollow 427 adjusting screw that has an interference thread. The Nascar rocker arm has the advantage of offering a 1.75 ratio as opposed to 1.60. Part number for it is C9AZ-6565-B and with it you will need a smaller new shaft C9AX-6563-A and a matching support C9AX-6531-A. Completing the valve train are the original nylon gears and the straight chain drive. How do you make it longer lasting? “Change it every four weeks,” says Gapp.

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Gapp launches his Maverick at 7500 RPM with a big heavy flywheel and a dual disc clutch that is a carryover from the days of his 1965 AFX Comet. A Hurst shifter is used to move some pretty unique parts inside the transmission. Among them there is a 2.54 first gear which provides lots of torque for getting out of the gate. Doug Nash Racing Enterprises does some tricky things to the upper three gears. They remove the brass blocker rings at the synchro. Next they also do away with the row of teeth that are engaged by the synchro sleeve. A precision ground shoulder now makes room for pressed on sleeves with wider, longer and stronger teeth – just about indestructible, unless you go around practicing missing shifts. Two out of every three teeth on the synchro sleeves are removed on all gears but first. Shift bars and the snap rings were tossed together with the blocker rings. Now, shifts are completed at 7800 to 8000 and the car goes through the eyes at 7500 rpm.

A 3 1/8 inch drive shaft with a heavy duty Ford truck yoke leads to a 5.12 Dana rear. Most recent change has been the switch from 8 to 10 inch wide rims which seems to have made the slicks more stable. Wayne is not partial to any particular tire maker and works with all three. The ET slip makes the selection. Warmup runs are made with a spectacular smoke screen, but during the run smoke is a no-no because it costs time.

It’s clear that Gapp and Roush are on the way to producing some serious competition in the Pro Stock ranks.

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