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1976 Pinto – A small Mystery solved

One of the questions that I have had is where did the 1976 Pinto that Gapp & Roush used from early 1976 to mid-1977 come from?

The 1977 car was a Don Hardy car, the 4-door Maverick and Mustang II were Hardy cars.

The 1973 Pinto was built as the first Wolverine Pinto chassis and the 2nd delivered and the 1972 Pinto and Maverick were a mix of Wolverine and Gapp & Roush engineering.

The 1976 car was built by Wolverine and modified by Gapp & Roush.

From the 1976 Gapp & Roush press kit:

Gapp & Roush 1976 Ford Pinto

“The current Pinto differs from its previous versions in that considerably more advance planning and engineering went into the initial chassis construction so as to produce the lightest possible basic body, an obvious advantage for this year’s all-out match race wars, as well as giving Gapp additional weight distribution flexibility at national events.

The basic tube frame chassis is the product of Wolverine Chassis in Romulus, MI, but the final construction and detailing of the car was completed in the Gapp & Roush shop, with many of their own components installed on the machine, reflecting their own individual approach to the racing game.”

Gapp and Roush – Super Stock Magazine, July 1974 article about the Mustang II

Originally Published in Super Stock Magazine, July 1974

Gapp and Roush Build A Pro Stock Pony

SuperStock July1974 MustangII

The World Champions unveiled their latest creation at Gainesville, a Mustang II Pro Stocker that captured runner-up and set Low E.T. of the Meet on its first outing!!!

By Alex Warlordy
Ektachromes by Bob McClurg

The latest thing out of the famous Livonia, Michigan shop is the beautiful Mustang II that has already to turn some of the quickest and fastest times this year.

02 Heads and PistonsAbove: Jomar girdle for the rocker studs is modified by G&R by adding extra spacers and by making up internal locking screws for the stud nuts. Rods and pistons used are by Brooks Racing Components. Rod length is longer tha stock at 6.060″, while piston design is by G&R, featuring a wide centrally located fire slot

WHEN FORD INTRODUCED the Mustang II, almost immediately, there was talk of the possibility of a Pro Stock version of the new compact. However, the optimism was dimmed a bit, as many felt that the care could not be as competitive as the Pinto because of the Pinto’s allegedly superior aerodynamics, and a structure which was inherently better for drag racing.

Nonetheless, Wayne Gapp and Jack Roush, who field one of the two most successful of all the Pinto’s, got right to work constructing a Pro Stock pony car. Any doubts that the car could be competitive were quickly dismissed when the are laid down a sizzling 9.03 at 152.88 mph on its maiden pass at the recent Gatornationals, good enough for the number two qualifying spot. During Sunday morning’s timetrials, the car managed to set Low E.T. of the Meet at 8.88. Then, during eliminations, the car managed to set Top Speed of the Meet at 153.06 mph with elapsed times of 8.94, 8.97, and 8.95 before losing in the final to Wally Booth’s Hornet with a nonetheless very fine 9.01 at 152.02 mph. To top all of this off, on the following weekend at Cecil County Raceway in Maryland, Roush cut an incredible 8.84 at 154.90 mph. Since this was for a circuit race, the run was made at NHRA legal weight of 2420 pounds.

Even the most die-hard Chevy or Mopar fan should have his curiosity aroused by now, so without any further ado, we’ll get right into the details of the new Gapp & Roush contender.


The new Mustang racer was assembled from individual body parts rather than from an entire car. This eliminated may hours of scraping off sealers and insulation, and also provided better control over the acid-dipping process. All panels have been treated except for the roof, quarter panels and the driver’s door.

A&A Fiberglass supplied an entire one piece front end for the car, which has been glassed onto a magnesium tube frame. This entire front section, together with the radiator and aluminum inner fender panels, can be removed in a matter of minutes for easy access to the engine. We get auto glass Portland OR. Also provided by A&A are a fiberglass dashboard and hatchback, again, to keep the weight down.

The car was assembled from individual body panels rather than a complete car in order to maintain better control over the lightening process.

The chassis for the 96″ wheelbase care is a Don Hardy creation featuring widely-spaced double-tube frame rails under the floor pan. It is constructed from a combination of both square and round tubing, and is extremely rigid. The main roll bar loop is cross-braced with an “X” type support construction within, and is also tied into the frame rails both fore and aft by individual struts. The firewall is also tied into the roll cage for additional strength.

08 Tube frame

Double tube subframe ties into the roll bar cage to form a very rigid structure. Ladder bars attach to the subframe.

Steering is handled by a Pinto rack-and-pinion unit, which is solidly fastened to the very front of the frame, and which used in conjunction with aluminum uprights, steel spindles and steering arms cut from chrome moly stock, all of which were supplied by Strange Engineering.


Wayne Gapp gets the credit for designing and dialing-in the suspension. Up front, there are specially lightened upper and lower control arms which have been designed to clear the front header pipes without necessitating severe bends in the tubes. Monroe coil-overs keep the front end up.

09 Front End Suspension

Special aluminum uprights were supplied by Strange Engineering. Careful front end layout eliminates camber changes and toe-in.

Monroe coil-overs are also utilized in the rear suspension, which does away with the stock-type leaf-spring set up. A pair of very long ladder bars extend well forward under the chassis, attaching to the aforementioned frame rails.

Ballast location is critical in the suspension, both to control excessive wheelstanding and the same time, to allow maximum weight transfer. This calls for multiple ballast locations, a requirement which was filled by having a large ballast bar with two grip handles bolted to the back of the roll cage, and also having a fabricated ballast tanked flanked by a pair of 50-pound batteries at the very rear of the car.

In the Gapp designed suspension, the idea is to have the car take off with minimum rise in the front , with no rear axle movement in relation to the quarter panels. On a track with good bite, this means tightening up the front shocks and shifting ballast to the forward mounting to restrict front end rising, while on a slick track, the shocks would softened up a bit with most of the weight in the back. In either case, the front tires should never clear the ground by more than a few inches for the first fifty or so feet of the track.


The Mustang II currently runs a full-sized 351 cubic inch Cleveland engine, although their car is light enough so that with a minimum of reworking, this can be swapped for a 320 cubic inch motor based on the Boss 302 (see April ’74 SS&DI-“327 Ford”). They have one of these motors ready to drop in should they so choose, for instance, if a situation arises where they feel they can derive overall efficiency per cubic inch from the smaller inch motor.

So far, the car has run a best of 8.84 at 154.90 at NHRA legal weight.

The 351 that they now run features the stock bore and stroke of 4.005″ x 3.500″. Since the Cleveland engine has an oiling problem at high rpm, the block must be massaged to get it up to par. Gapp and Roush have designed restrictor kits which are produced by Moroso which they themselves utilize. These restrict the oil flow to the cam bearings, the lifter galleries and the valve train, and provide increased pressure to the main bearings where it is needed. This is further enhanced by the use of a 100 pound oil pressure relief valve.

The Boss 351 crank is modified to accept Chevy-sized aluminum rods which were designed for the Ford by BRC. The stock external counterweights are eliminated in favore of welded internal weights, which reduces excessive loads on the front and rear bearings, and also helps prevent high rpm bending of the crank. The internal weighting is done with tungsten carbide, which costs $7 for a linear inch of one inch round stock.

03 Crank

Slugs of a very heavy Mallory alloy are pressed in to the stock counter-weight so that the crank can be internally balanced. External counterweighting is eliminated.

The stock 5.775″ length Cleveland rod is discarded in favor of the aforementioned Brooks unit, which measures 6.060″ end-to-end. This is use in conjunction with a specially designed BRC piston for which Gapp and Roush designed a special maximum compression popup and a broad fire-slot. The tapered wrist-pin is located just under the oil ring to make up for the additional rod length. Finally, the ring combination is a special Gapp and Roush design, utilizing a ductile moly-filled top ring, a low tension cast iron second ring and a low tension 1/8″ oil ring.

Since the steering unit has been moved forward, a rear sump pan must be used for adequate clearance. Oil movement is controlled by no less than three trap doors, and the capacity is provided by two side “wings” on the pan, which are necessary to keep 20-40W Pennzoil away from the crankshaft area within the confines of the very low car (which prevents a very deep sump). A special Econoline oil filter adapter is necessary to align the filter parallel to the block (rather than sticking straight out) so that it clears the inner panel fenders.

04 Louis and Oil Pan

A flexible connection is used between the oil pick-up and the oil pump. 100 pound relief spring and a restrictor kit help increase flow to the mains.

05 Oil Pan2

With the steering arms having been moved well forward, there is room for a rear sump oil pan featuring three trap doors (pan on left in image). Stock pan to the right.

Induction is handled by a pair of 6464 Holley 4500’s which have been specially modified by Gapp and Roush for smoother flow. A close examination reveals that the inlet area to each barrel has been radiused carefully, but the other internal modifications are something that Roush is reluctant to divulge.

The carbs sit atop an Edelbrock manifold that has also undergone thorough massaging. For cooling purposes, the webbing between the individual runners has been cut and ground away, allowing air to circulate freely around the runners. Also, the plenum volume has been reduced by sectioning to improve response, and also for proper height in relation to the hood scoop. Needless to say, the finer details of the internal mods are not open for discussion.

07 intake manifold

The Edelbrock manifold has the webbing trimmed out from between the runners before installation, as this allows freer air circulation and hence, a cooler air mixture flowing into the head. Roush sections the plenum to reduce volume as this seems to imporove enging response and assures proper seal for the carbs within the hood scoop. An aluminum water pump unti from a 289 is used, but requires a half-inch spacer welded to the engine mount for proper clearance. Note the use of the undersize crank pulley, which reduces fan speed, and also prevents belts from flying off at high rpm.

The manifold passes the intake mixture to the now famous “high-port” Cleveland heads for which Gapp and Roush now supply the aluminum plates for raising and straightening the exhaust ports. The crossover passages in the exhaust ports are epoxied shut, and the combustion chambers are thoroughly cleaned up, not to mention the usual porting and polishing. The valves used are 5/1″ stem lightweight items from Manley, for which the valve guides must be bronze-bushed. To complement the trick heads, notches are cut in the blocks at the tops of the cylinders in the area of the valves in order to aid flow. The cut is about 1 1/2″ wide, and tapers gradually to just above the ring travel where it blends into the cylinder wall.

The valve actuation is obtained from a 321/329 General Kinetics camshaft featuring 330° degree of intake duration and 340° of exhaust duration. At .050″ lift, this figures out to 284° and 294° of duration. The cam is run at 2° advance. The roller tappets are also GK, and are used in conjunction with special Gapp and Roush pushrods. Also included in the valve train are stock Ford pushrod guide plates which have been split in half so that the GK roller rockers can be individually centered on the valve stems, and a Jomar stud girdle to which Gapp has added some of his own modifications (such as internally locking adjusters and center spacers for improved supporting action).


Wayne Gapp prefers to use Accel components exclusively, utilizing the Accel BEI system in conjunction with Accel wiring and Yellowjacket spark plugs. The BEI system features a black disc which is mounted on the distributor shaft, and which regulates the emission of light from a diode onto a photo transistor. Whenever the transistor receives a light signal, it triggers the spark to the plugs. This system provides timing accuracy to within one-quarter degree, and packs more than enough energy to keep the plugs firing and very high rpm. The high energy output of the BEI allows the setting of the spark plug gaps at .035″, slightly wider than normal, and this provides slightly better combustion efficiency.


Back of the Weber 40 pound flywheel is a Long-style Weber single-disc clutch unit. The bob weights at the ends of the release levers have been trimmed down, as Roush feels that even this small amount of weight can cause creeping and hence a red-light, when sitting at the line at 10,000 rpm. The spring pressure in the clutch has been intentionally limited to 2800 pounds to give a little cushioning effect during hard shifts so as to protect the driveline pieces. The entire assembly is contained inside a Lakewood scattershield.

06 Weber Clutch

The Weber clutch is run with a solid disc, and has the bob weights at the end of the release levers trimmed off to prevent creeping while revving at the starting line. The spring pressure has been limited to 2800 pounds to allow cushioned engagements and so to protect the drive line during hard shifts.

The 3.10 low gear Lenco passes the power back via a 20″ driveshaft to the specially modified Ford rear end. Inside is a set of 5.67 Schiefer Pro Gears using the 9″ ring gear, which transmits the torque through the Strange axles to the 14x32x15 Firestone tires mounted on Motor Wheel wheels. The front tires are also Firestones, and are also mounted on Motor Wheel units.


The exhaust is handled by a set of Jr. Headers, which have primary tubes measuring 2 1/4″ in diameter and 28″ ling dumping into a 4″ diameter collector. The headers were specially designed to be used in conjunction with the control arms to provide a minimum of bends.


Gapp and Roush give special credit to Bill Jameson, Don Hardy, Al Buckmaster, Diana Gapp, Louis Wolsinski and Ken Moe for assistance in putting together the car. Special thanks also go to Chuck Miller, who applied the beautiful blue and pearl paint job, and to Paul Hatton, who did the lettering.

At present this car is one of only two Mustang II Pro Stockers in the country, the other belonging to Don Nicholson. Both cars have run very well, and should Roush’s success continue, it just may turn out to be the successor to the Pinto’s as the dominant car in the Pro Stock Class.

Bridging the Gapp

Originally published in Car Craft magazine, May 1976

For four years now, Wayne Gapp has been brutalizing Ford rear-ends, to the delight of the photographers lining the guardrails of the nation’s drag strips. You see Wayne slalomingo ut of his water burnout and brace yourself for the crack of his dry chirpies as his Pro car bounces into the staging lights. The wall-to-wall Firestones literally melt into the pores of the pavement as the engine screams. The clutch drops, the front tires are free of the earth, and Gapp lays down another 8.80 pass.

It’s a rare occasion when something breaks in the former World Champion’s car. An engine might let go, or a clutch cause problems,but a rearend-never. For racers who have difficulty putting together three passes in a row, Gapp’s invulnerable race cars are a marvel. Whether there is a Maverick, Mustang or Pinto body shell wrapped around the tube frame, a 9-inch Ford rearend is always charged with transmitting his Boss engine’s considerable power to the rear wheels.

Gapp and Roush’s allegiance to the Ford rearend could be dismissed as the prejudice of a pair of former Ford engineers, but the two Pro Stock stars have several convincing reasons to explain their choice. First is the Ford’s unique bearing design, which supports the pinion at both ends. All the other rearends commonly used in racing support the pinion only on its shank, so under load it “walks” away from the ring gear. This deflection is a major cause of breakage.

Secondly,the Ford rear is a Hotchkiss type, which simply means that it has a removable center section. lt is infinitely more pleasant to set up a ring and pinion with the carrier sitting on a workbench than it is to do while lying on your back under a car, as Dana 60 and Chevrolet 12-bolt owners must do. The removable center section also permits easy replacements, since the spare can be completely adjusted for backlash and pinion depth before installing it in the car.

The Ford rearend is virtually standard equipment in stock car racing, and consequently there is an enormous variety of gear ratios available. In the range most favored by drag racers, 5.83, 6.00 and 6.20 gears are all produced for Ford rearends; a Dana 60 must jump from 5.88 all the way to 6.17. In a sport where power are narrow, the flexibility in the ratio selection provided by the Ford rearend is a considerable advantage–which is why a number of GM and Chrysler racer are beginning to sport FoMoCo rearend housings.

All is not sweetness and light with the Ford, however. If there is a problem with the design, it is the gears’ hypoid angle: The pinion intersects the ring gear very low. Thus the Ford rear absorbs more horsepower than other rearends commonly used as the attached chart illustrates. Roush rises to the the rearend’s defense by pointing out that the other rearends’ superiority disappears when the ring and pinion deflect, as they unquestionably do under the loads imposed in drag racing. Considering how close competition is between the top teams in Pro Stock, it’s unlikely that Gapp and Roush are going to give away any horsepower to an inefficient rearend.

Since the Ford rearends have not developed the mystique of the Dana 60, they can be obtained for very little. The 9-inch rearend was installed in almost everything that ever rolled off a Ford or Lincoln-Mercury assembly line. Thunderbirds,Galaxies, Broncos, E-200 Econolines-you name it, and it probably had a good rearend.This permits a low-budget bracket racer or street runner to shop around for a rearend with the proper width to tuck wide tires under the car. One should beware of imitations when hunting a Ford rearend, however. The 8-inch versions which generally inhabit the undercarriages of Falcons and light-duty Mustangs look very similar, but are definitely to be avoided. Take a tape measure on your expedition and check the ring gear diameter if in doubt.

Like any part used for high performance or racing, the Ford rear has some trick pieces which increase its chances of survival. The carrier to look for is made of nodular iron, which Ford thoughtfully identified with an “N” cast in the side to aid your inspection. Gapp recommends the largest pinion bearings which Ford offers, which go under B7A-4621-A for the front, and TBAA-4621-A for the rear. The pinion retainer for these bearings is the ever-popular C3AZ-4614-B.

Setting up a Ford rearend is straight-forward procedure which is explained step-by-step in shop manuals. Remember that adding shims behind the pinion bearing retainer move the pinion away from the ring gear; in other rearends, adding shims behind the pinion has the opposite effect.

The fight against gear deflection has gone to extraordinary lengths at Gapp’s Livonia, Mich., shop. When Wayne drops the clutch and the ring gear tries to escape the rearend. Its progress is arrested by a “load bolt” inserted through the side of the third member. This brass tipped bolt bears against the back side of the of the ring gear, which is polished smooth. This bolt is adjusted so that it lightly touches the ring gear when the rearend is first set up. Under load, the pinion tries to force the ring gear away, but the load bolt prevents this sideways movement. The lessened deflection provides longer gear life and peace of mind for Gapp at the starting line.

The remainder of the racing Ford rearend is conventional. Grade 8 bolts secure the ring gear to the spool, torqured to 100 ft-lbs and doused with red Loctite for insurance. The 1/2-inch studs which hold the steel rearend caps are also tightened to 100 ft-lbs, and steel spanner nuts are used to the adjust the backlash. The outcome of all this metallic overkill is a rearend which seems totally indifferent to the abuses of 700-horsepower engines and 28 inches of racing rubber glued to the asphalt.

Ford 351 Performance Secrets

Originally published in Popular Hot Rodding. 

Ford 351 Performance Secrets

The small-block Ford’s performance potential has finally been realized,
thanks largely to the efforts of the Gapp and Roush team.

Taxi middle page 2

Ford may be out of racing, but Gapp and Roush are definitely in it, in a big way. You can never be sure whether a Ford or Chevy will occupy the top slot in Pro Stock, but the odds are better than even that the Gapp and Roush-prepared Ford machinery will win. They have been more than willing to share their knowledge with other Ford owners; as a result, their shop at 32081 Schoolcraft, Livonia, Mich., has gained fame for Ford engine work.

In this particular story we are going to concentrate on the hottest, fastest Pro Stock engines. That same engine information also holds true for Modified or Competition Eliminator engines. Incidentally, Jack Roush is now working to expand the engine shop to build engines not only for Pro Stockers but also Super Stockers, extending the Ford activities by a wide margin.


You should begin with a ’71 Boss four-bolt main bearing block. These blocks were available in production vehicles, so parts are still obtainable over-the-counter. So far, no block has superseded these. They cost only $40 more than a stock block with two-bolt mains, so it hardly pays to upgrade the street block. However, the material is there to convert from two bolts to four bolts, if you insist.

351 top page 2

Edelbrock manifold is mounted backwards to help clear the ACCEL BEI distributor.
Note the raised rocker covers needed for the Jomar stud girdles.

Every block receives two neat chamfered sections at the top of each cylinder bore, leaned back to the edge of the gasket in the vicinity of the intake and exhaust valves. This chamfer extends down to the top of the ring travel on the wall and helps both the intake and exhaust valve flow. Since the exhaust is closest to the bore, it’s also the most important one.

351 bottom page 2

An old-style aluminum water pump bolts up to the engineplate.
1/2-inch adapter heliarced to the plate helps line up the pulley. 

The block itself is of good quality. All the head bolt holes are blind, meaning that they don’t exit into the water jackets. You shouldn’t have to retap them; just clean them out. If you are using a new block, there also shouldn’t be any need to O-ring the decks or to align bore the mains.

The block receivesa conventional amount of deburring but no painting. Jack Roush feels that paint just seals in dirt and prefers instead to spend the extra time on cleaning. Jack has made up a set of 1 1/2-inch-thick torque plates which he bolts to the top of the block before honing the bores. A succession of different Sunnen honing stones brings the finish to an unbelievable 800.

It so happens that a special five-fold super gasket is available from Ford for this particular engine as a standard release item. It was originally designed for racing use but was later relegated for the production line. The part number is D3ZX AA.


A stock 351 Cleveland crank makes use of external counterweighting. There is a large bob weight built into the crank damper and another one incorporated into the flywheel. This provides the external forces needed to keep the engine from vibrating excessively. However, those forces can also get large enough to bend the nose of the crank when you bring the engine to racing rpm, which about double what a stock engine will see.
Centrifugal forces, as you know, increase as the square of the speed; so the bending loads on the crank nose are easily four times as high.

Crank bottom page 3

The bob weight is cut out of the front damper assembly, an a neutral balance flywheel is also used.
Three slugs of Mallory metal are fitted lengthwise into the crank.

This can be prevented by getting rid of the external counterweighting. In this case, the crank damper is machined out to remove the bob weights, and the Weber steel flywheel, which is used has no counterweighting.The loss of external weighting is compensated for by drilling out holes in the end counterweights of the crank. These holes are then-filled with sections of rod made of Mallory metal (tungsten carbide) which is considerably heavier than steel. The tungsten carbide rod happens to cost $7 an inch, and at least six inches of it must be used per crank.

Some racers have had these kinds of weights come out of the crank because of centrifugal force, but Roush has no such troubles. His explanation is that counterweights were never intended to be inserted into radially-drilled holes (holes drilled perpendicular to the crank centerline). Centrifugal forces can definitely throw them right out. When Roush prepares a crank, the holes are drilled into the counterweights length-wise, parallel to the centerline of the crank. They are also not drilled all the way through, and they are left with a chamfer at the bottom. The pressed-in Mallory weight sare closely fitted to the bore,and they are also chamfered so that they seat very snugly. A touch of arc welding or staking at the free end then suffices to hold the weights in place. The rest of the crank work depends on the rod combination, and this brings us to a discussion of connecting rod preparation.


All of the Gapp and Roush engines are built with aluminum rods.They have not had any problems with steel rods simply because they have never used them. As Jack explains it, some racers have been very successful with steel rods and some haven’t, but in an all-out engine the aluminum rod is the only way to go for the ultimate in reliability.

There are several choices available here. Brooks makes a small-block Chevy rod with a blank wrist pin end so that you can put in the pin at any height. Since it has a smaller rod journal diameter than Ford rod, the crank must be reground to fit. However, you can place the centerline of the new pin either further out or further in without having to do any welding. This allows you to build anything from a 340-inch to a 370-inch engine, dependingon how you stroke the crank. The rod length on the stock 351 is 5.775, but Jack goes to a 6.060-inch rod with the 351 engine. If you use a small-block Chevy rod, the crank journal must be widened, cut down, Tufftrided and polished. It is by far the best combination, but it’s also the most expensive.

If you are building a budget engine, you can use a Brooks rod which has been machined from a big blank. It is delivered to accept a standard TRW piston and stock rod length, or you can get a Brooks piston and achieve a 6.060 rod length. With a good transmission that doesn’t give you over-revving problems via missed shifts, the aluminum rods are good for as many as 75 runs before they have to be replaced. They won’t necessarily break then, but the engine is worth a lot more than rod replacenrent, so it’s better to take the safe route at this point.


Originally, all of the Gapp and Roush engines were based on the Boss 302 Trans-Am pistons which gave a good long rod combination and an acceptable dome shape. When Ford quit marketing performance parts, Gapp and Roush started working with Brooks on a piston that would be manufactured exclusively for them. Little changes were made, beginning from a basic prototype, until the final piston dome evolved. The piston that Brooks makes for Gapp and Roush is closely held to the final prototype dimensions, so that you always know what you’re getting. It has a fire slot designed to give plenty of clearance so you don’t close up the spark plug, and the piston design allows a good flame travel path without losing to much compression. The rest of the dome is fitted close enough to the head to allow for a healthy 12.75-to-1 compression ratio.

Pistons left middle page 3

Convenient grooves on this Brooks piston tell you were to mike it.
The pins are retained by double Spiro-Locks. The pin is oiled directly from the oil ring land. 

Because things are very competitive in Pro Stock, the most radical cams must be used, and consequently it’s very difficult to control valve action. As a result, Jack Roush specifies a minimum piston-to-valve clearance of .100-inch. He considers that it is more important to keep the engine together with this kind of insurance than it is to get an extra fraction of a point in compression. One of the little bits of piston detailing is a groove which Brooks machines to show where the piston should be miked, right about at the level of the wrist pin bore. This gives the engine builder a chance to always pick up the correct piston dimension. Jack suggests a .010-inch piston-to-wall clearance. Regardless of which aluminum rod you use, the Brooks pistons come through fitted with weight-saving taper pins. They are held in by double Spiro-Locks on each side.

Gapp and Roush have worked out a special ring combination.They buy the individual rings in bulk from Sealed Power and then make their own sets designed for low drag.This includes a moly-fitted top ring, a ductile iron second ring and a l/8-inch oil ring. These rings are, of course, built to fit the cylinder bore with the proper end gap. In other words, they have the right pressure pattern and the right radius. When you try to use an oversized ring in an effort to close up the end gap, the geometry and pressure pattern of the ring is altered and you run into problems. If you want to take care of your vision health you could also use an Outback Vision Protocol package program that really help with this and you can find it online.


Raising the exhaust ports by milling the exhaust side of the head and adding an aluminum plate had yielded a good solid 25 hp. The round exhaust port in the plate measures just 1-5/8-inch in diameter, and the 21/4-inch header bolts right up against it. This forms a sizable “step” which Roush considers important in preventing a reflected pressure wave from coming back into the port. No similar steps have been built into the intake.

Heads top page 3

Gapp and Roush make up their own cylinder head side plate.
By the time the ports are reworked, they are good for 25 extra horsepower or more.

An extensive amount of flow work is done on the heads. As long as Gapp and Roush keep winning in the fashion that they normally do, you can’t have much doubt that their heads work. Special head bolts of stock size are used, but they are better than Grade Eight. To keep them from biting into the cast iron or the aluminum, thick hardened steelwashers are used. We might mention that Gapp and Roush sell their aluminum head plates either finished or rough, depending on what you want. They also produce finished heads.

Heads page 4

The combustion chamber volume is set at 60cc.
Extensive flow work has been done on the cylinder heads, including a general clean-up of the ports.


Cam page 4

Hardened push rod strips eliminate wear at the guide plate.
Also, an extra relief is machined into the rockers to clear the valve spring retainers.

The valves have been a problem since Ford titanium valves have disappeared from the face of the earth. Ford doesn’t have them and neither does TRW. As a result, a switch has been made to Manley valves with 5/16-inch stems. This, in turn, calls for Manley bushings to be inserted into the valve guide to take up the difference in diameter between the stock guide and the new valves. Titanium retainers are used, but Roush cautions that numerous spring and retainer problems can arise. Titanium is stronger while aluminum is lighter, but both seem to pull through when a spring is stiff enough to contend with the radical cam in use today. Roush prefers aluminum retainers when they can be fitted. Generally, the rockers are relieved to accept 1-5/8-inch valve springs.

351 middle right page3

General Kinetics supplies the roller cam and roller rockers.
The 1-5/8-inch valve springs receive either aluminum or titanium retainers.

The push rods have hardened tips and do now wear out at the guide plate. They are also fitted with .040-inch oil restrictors to cut down on the top end oil flow. Stock Ford guide plates are paired and Gapp and Roush prefer to split the stock items in half and use them individually. The nose of each rocker can then be centered on the valve by simply drifting around the individual guide plate with a punch and a hammer. Completing the top end is a Jomar stud girdle which consists of a pair of bars, one for the intakes and the other for the exhausts. Normally, they are supplied with a pair of spacers that stiffens the assembly still further. Completing the valve train is a General Kinetics 321/329 rollercam.

Heads valves page 4

The rocker adjusting nuts receive a center lock which comes in handy when adjust the valves.
Note the individual guide plates which are not paired as they are on a stock Ford. 


One of the reasons that Jack Roush runs aluminum rods is that they save on reciprocating weight. He also feels that they allow the engine to run well with less oil pressure, thus providing a sort of extra margin for the oiling system. Jack feels that, in an all-out engine, aluminum rods are the way to make the engine live, especially above 8500 rpm. The modifications to the oiling system itself are designed to keep pressure at the bearings, but here again nothing particularly exotic is done. There’s just a lot of attention to detail.

Engine page 5

With a low-slung car and rack-and-pinion steering, you can switch to a shallow oil pan with a rear sump.
A Hemi-type ACCEL wire harness has been adapted to the 351 engine.

We mentioned the restrictors at the push rods. Additional .060-inch restrictors are pressed into the galleries leading to the cam bearings. On a 351 Cleveland engine, the right side lifter oil gallery feeds the mains as well as the lifters, while the left side lifter gallery feeds only the lifters themselves. Consequently, adding a .080-inch restrictor to the left side gallery cuts down on oil pressure loss to the mains. Finally, the production oil pump is fitted with a 100-lb.pressure relief spring. No changes of any kind are made in the crank oiling system other than to chamfer the holes on the main journals after cutting the crank to size.

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 In a car where you have more ground clearance, a more conventional deep sump pan with simple baffling can be used.

On his own car, Wayne Gapp uses a reverse sump oil pan with the deep part of the sump at the rear of the engine. This is specifically designed for Pro Stock cars which use rack-and-pinion steering systems and have very low car height. This type of pan is fitted with a bustle, or side wing, to retain extra oil without getting into ground clearance problems. A flex hose runs from a fixed pickup in the pan on forward to the oil pump. On some engines, this flex hose is replaced with a fixed pickup, depending on racer preference. A good rule of thumb to follow is that rigid pickups are easier to get on and off, while flexible onesare less likely to break.

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A flex hose connection (arrow) between the oil pump and the fixed pickup does away with breakage. 

Since a great deal of oil must be contained within a shallow sump, an elaborate system with three trap doors is used to handle oil slosh on take off and braking. If you are running a car with conventional steering linkage and don’t want to go to a “tunnel” pan, Gapp and Roush also make a conventional deep sump pan with a pair of baffles. It’s simpler, less sophisticated and less expensive,thanks to taking advantage of available ground clearance.

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Here individual trap doors channel the oil towards the center. The front part of this oil sump is fairly deep.

If you have problems with fitting the oil filter, chances are that a right-angle adapter from a 300 Econoline six will solve your problems.

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If you run out of oil filter clearance at the chassis or the headers, use this adapter from a late-style 300-cubic-inch Econoline six.


The Edelbrock intake manifold normally comes through with webs tying in all the runners. For Wayne’s own car, the webs are cut out for extra cooling. No welding is needed since the stock one-piece gasket seals off the underside. Both the manifold and the plenum are cut at their mating surface to gain some hood scoop clearance without having to do any heliarcing. Also, the top of the Edelbrock manifold is machined to clear the distributor. Both of the Holley 6464 carburetors have had the tops cut down and the entry area radiused. Here again, you gain clearance and improve flow.

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All of the webbing has been remov from the intake manifold, increasing the cooling.
No welding is needed, thanks to a stamped, one-piece intake manifold gasket.


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The manifold and plenum have both been cut down to gain added hood clearance.
Additional hood clearance comes from cutting down the tops of the 6464 Holleys. 

There’s much more information available from Gapp and Roush on all types of Ford competition engines, and you’ll be reading about it soon in POP ROD. In the meantime, it looks like Ford fans have reason to be proud. Ford performance is back!