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Formula Ford

Legal & Proud

Ed.  The following is a web recreation of the article originally published in Rocky Mountain Vintage Racing's APEX magazine, Spring 1999 issue.  The text is as originally published, the photographs had to be re-created due to the loss of the originals.  Some of the information, may be dated.


- By Bob Darcey and John Mihalich, Jr.

The question of scrutineering for engine legality in Vintage Racing is frequently raised, but seldom resolved. We all acknowledge that, in the grand scheme of things, the difference between placing first and last in the game of Vintage Racing (a.k.a. 'old farts trying not to hit each other') is relatively unimportant. What is important, though, is that the "playing field be level" and that, win or lose, the game is played fairly. In the RMVR Formula Ford group, we have developed a functional solution to the problem, and we would like to share some of the philosophical and technical aspects of the program with our fellow racers.


Formula Ford was originally conceived as a driver's training class, and the cars were actually first developed in England as inexpensive, rugged vehicles for driver school students to beat on. Eventually, the popularity of the class caught on, and rules were developed to maintain the "low cost" objective of the class; in the U.S., the SCCA/GCR rules paralleled the rules in Great Britain, limiting engine development to standard Ford 1600 components with very specific restrictions. This "formula" created a very popular class in Europe and here in the U.S., and a number of future road-racing stars had their roots in FE The class was affordable and emphasized a driver's skill rather than radical engine development and mega-buck expense.

Vintage racing came along, and vintage FF soon became Formula Fords on steroids. Because there was "nothing to win," there was no scrutineering and the class became full of "wild" motors with big cams, aluminum flywheels, Carillo rods, and so on. A common line was that "It's not legal for SCCA, but it's OK for Vintage." In 1992, when I was looking to buy a FF, I passed on a pretty good deal because the seller told me about the big cam and aluminum flywheel that he had in the motor. Then, at my first RMVR event, I counted six aluminum flywheels on FFs! The ultimate explanation: "There is absolutely no cheating allowed in RMVR, especially in your rookie season!" Back then, VARA tried an interesting response to the problem, allowing .040" overbore, big cams, big valves, light flywheels, billet cranks, etc., only to find that people would cheat on those rules, too! Obviously, re-writing the rules was not the answer. The original intent of the FF class was getting lost.

In the fall of '95, we put out a questionnaire to the RMVR FF group, primarily to start a dialogue and hopefully develop a consensus on what could and should be done. The results were overwhelmingly in favor of random scrutineering, just enough to keep everyone honest. While the questionnaire did identify a consensus, no one wanted to be the "cop," and the plan to scrutineer stalled, although some of the "really stout" motors went away. We talked a lot throughout the '96 season, and toward the end of the season began a voluntary program to demonstrate that our engines were prepared in the spirit of the GCR rules. This program came to be known as "FF: Legal & Proud" we chose to make the program voluntary for a number of reasons:

1. There is no RMVR Board sanction for mandatory scrutineering.

2. If a racer doesn't embrace the philosophy of running legal, he will find a way to cheat in any program. These same people probably cheat at solitaire.

3. Racers who volunteer to participate in the program understand that Formula Ford racing is at its best when the cars are on as 'level a playing field" as possible.

Oddly enough, about this same time some VARA FF drivers put out a questionnaire, much like the RMVR effort, and subsequently developed a similar program. While the VARA inspection is not as intensive as the RMVR program, the philosophy is the same. The results we've seen so far, both in RMVR and VARA, are gratifying: our lap times are closer, the front pack is larger, we're paying more attention to chassis setup and driving "at the limit" and bitching less about so-and-so's "cheater motor" We're also having a lot more fun.


The items to be inspected are listed in the Legal and Proud Verification Form, which specifies the appropriate dimensions and is available to anyone considering joining the program. It would seem obvious that anyone volunteering to have their motor inspected is probably fairly confident that the thing is correct, but this is not always the case. Review of the form, prior to requesting an inspection, is always a good idea. The inspection process consists of eight steps; if the criteria at any step is not met, the engine is declared "illegal" and the inspection process stops. As a matter of policy, negative results are not discussed with anyone but the owner.

STEP ONE is a visual check of the value train, carburetor, intake manifold, and flywheel for correctness. Formula Fords can be run with either a "Cortina" configuration motor or an "Uprated" unit, and the appropriate declaration is made at that time.  "Uprated" head is flush, the uprated pistons have cast reliefs to provide valve clearance. Aftermarket high-compression pistons can usually be detected visually, but stock units modified for higher compression are common; measuring the bowl depth and diameter will identify those pistons.


Figure 1


STEP TWO in the inspection process is a measure of the overlap of the intake and exhaust valves to verify that the camshaft is proper. Figure #1 shows a typical pair of cam lobes. As can be seen, there is a point at which the intake and exhaust valves will be at equal lift at the "overlap" (exhaust valve nearly closed and intake valve just starting to open). If the duration of the lobe is increased, the total lift (intake + exhaust) at the overlap point will also increase. Based on numerous samples of stock Formula Ford cams, it has been determined that, at the point where the intake and exhaust valves are at equal lift, the lift is approximately 0.052" on each valve, or .104" total. If the sum of the two lifts substantially exceeds this amount, the cam is considered illegal. Figure #2 shows the L&P inspection fixture holding two dial indicators to obtain these readings; this could also be accomplished with two magnetic bases holding the dial indicators.

Figure 2


Figure 3

 STEP THREE measures the maximum valve lift for each intake and exhaust valve. SCCA/GCR regulations state that the maximum exhaust valve lift is 0.358" and the maximum intake valve lift is 0.356", measured with the lash adjusted to zero. The L&P fixture is used again to check the valve lifts as shown in Figure #3. If the valve lifts are in Spec, the head is removed.


Figure 4

STEP FOUR is the check of the intake and exhaust valve diameters, and verification of the combustion chamber depth. The engine configuration ('Cortina' or 'Uprated') is determined by the type of cylinder head in use. When the head is removed, it is first checked for its applicability to eithe "Cortina" or the "Uprated" declaration. Next, the valves sizes are checked for their applicability to the declared engine. Figure #4 shows an intake valve diameter being measured. If the head is a "Cortina," the depth of the combustion chamber is checked for minimum depth to verify compliance to the compression ratio limitation.


Figure 5

 Figure #5 shows the check of the combustion chamber on a "Cortina" head using a dial caliper; a depth micrometer is preferable, if available. "Uprated" heads are flush (i.e., do not have a combustion chamber).


Figure 6

STEP FIVE is a check of the engine's stroke, which is specified as 3.060" maximum for both the "Cortina" and the "Uprated" engines. A dial caliper can be used to check the stroke as shown in Figure #6, but a depth micrometer is more accurate.


Figure 7

STEP SIX is a check of the cylinder bore. The maximum piston diameters for the "Cortina" and "Updated" engines differ; the "Cortina" engine is permitted up to 3.218" diameter pistons (+.030"), while the "Uprated" engine can use only "standard" 3.188" diameter. Since we can't actually measure the piston diameter, we measure the cylinder bore and subtract .0 10". Figure #7 shows the dial caliper used to verify the cylinder bore.

STEP SEVEN is a check of the pistons. Since the pistons designs are different for the "Cortina" and "Uprated" engines, it is necessary to verify the depth and diameter of the bowl, as well as the correct application of pistons. Because the "Uprated" head is flush, the uprated pistons have cast reliefs to provide valve clearance.  Aftermarket high-compresstio pistons can usually be detected visually, but stock units modified higher compression are common; measuring the bowl depth and diameter will identify those pistons. 

STEP EIGHT is a check of engine deck height, the distance between the top of the piston and the top block; this dimension generally controls the compression ratio. In the "Cortina" engine, the piston is allowed to be 0.006" (max) above block deck while, for the "Uprated" engine, the piston should be approximately 0.026" (min) below deck. These dimensions correspond mathematically to the allowable compression ratios of 10: 1 for the "Cortina" and 9.3:1 for the "Uprated" configuration. Deck height is the area which presents the greatest difficulty for the inspector, since most blocks have been decked to some extent, many of them too far. Furthermore, there is some variation between piston bowl volumes which affects the allowable deck height. Most legal "Uprated" piston bowls measure at around 38.6 cc, which translates to a required deck height of -.027"; that said, we have seen some engines work out to 9.3:1 with as little as .022" deck height. If your deck height is less than .022", you'll need to have the engine cc'd to demonstrate that the compression ratio is legal; lacking documentation that the compression ratio is within legal limits, the motor will not be accepted and the owner can consider the following options: grind the pistons to provide more upswept volume, or fit the engine with non-standard, thicker lead gasket. While neither option is SCCA legal, we allow these options so as to avoid the expense and effort of building a new block. Formula Ford blocks are starting to become scarce; the goal is to eliminate illegal horsepower advantage, not to waste usable blocks.



The RMVR program has been operating now for about two years and, by all accounts, it has achieved the intended results. There are approximately 20 RMVR FF's running as FF: L&P, or over half the usual starting grid. Our lap times are often within a second and the races are more competitive, often with five or six cars battling for the lead. The program has created a core group of relatively equal-power motors, so it's become a lot easier to identify the guys who are still running the illegal stuff. Building these motors to the limit of the rules is a lot more challenging than paying $90 for a cheater cam and loading it in for automatic (and really obvious) 10 HP advantage. The equality of the motors in the group is most evident on long straights, where a well-timed draft is often the only way to pass. Most importantly, we are concentrating on improving our driving skills and chassis setups to get to the front. This is the way FF racing was intended to be, and this is what the program has helped achieve.

1999 - APEX - SPRING

 (New Photographs, 10/5/03 by MaryAnn Mihalich)

New Developments:

Connecting Rod, Small End Bushings, Offset Style

Bill Bradford, one of the Denver, Colorado, based engine builders has developed a scheme where he machines the connecting rod, small end bushing bore to accept an oversized bushing.  After installation of the oversize bushing, he machines the bushing ID off center, towards the connecting rod big end, and gains additional piston to deck clearance.  Bill says that up to .015" can be gained using this method.  Although not sanctioned by the SCCA, as an approved modification, it has become the preferred method of gaining additional deck height in Rocky Mountain Vintage Racing. It is the opinion of RMVR's and Bradford's that the .015" shorter connecting rod effective length provides no performance advantage. 


SCCA Piston Valve Relief Pocketing

The SCCA has addressed the issue of overdecked blocks by issuing the following rules change:

Item 5.  Modify the wording of the FSC section 17.2.6.D.2.e effective 10/1/01

3.  Pocketing of the piston valve reliefs is allowed up to a maximum of .050" to obtain the minimum combustion chamber volume. 

(from: Sportscar, October 2003, page F-276)

L&P Fixture drawing   (Adobe .pdf format)    (AutoCAD LT2000 format)

L&P Data Sheet     (Adobe .pdf format)

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