[Not sure if this will help, but I remember seeing a restored R-model GT350 a number of years a go (I think it was SFM5R104, originally raced by Mack Yates. It was restored with a 3255 carb from a 427 Med Riser because this is what Yates used. This was because it looked just like the 715 carb and was considered a "cheater" part that the average SCCA inspector probably wouldn't pickup on.
As for the cam, a friend of mine drove a 65 GT350 (5S048, I think) that had a pair of Valley Head Service prepared heads that had come off of a GT40 that Jim Toesing(?) had put a DOHC Indy motor in. This Shelby also had an Engle cam, called a 156. I remember seeing this cam being referred to in some old literature as being one that Shelby had used in some R-models. Seems like it was less than .500" lift, but is sounded good and was one of the fastest 289 powered GT350s I had ever been in. It would eat my 66 GT350 alive.
Dave]
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Going from memory so please correct me if I'm wrong, here are a few more changes done to at least some cars:
- Larger Holley 3255 carb, 780 cfm.
- R-Model intakes were not drilled for PCV vaccum fittings.
- Valve covers were standard steel units, each had a breather cap tube
- Electric fuel pumps
- Different camshaft?
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- R-3255 carburetor: SAI installed ? Who knows? I have heard that but never seen a period picture of one in use that I recall. A 715 cfm model would have been plenty capacity wise. Engines might have been homologated with them as an option as they were for the Edlebrock® 2-4V cross ram induction and 180° ‘megaphone’ headers. Old SAAC publications indicated that the 2-4V and 180º headers were put in the list of options but I don’t recall ever seen anything that noted anybody getting them on a new race car. Even if the installer removes all the features of the R-3255 for its 427 Ford O.E. application the air bleeds drilled into each bore near the venturi are real easy to spot even in poor photographs. I don’t recall seeing any new GT350 racer images showing holes in the sides of carburetors. If you have a new car pre-first owner shot showing air bleeds in the sides of the carburetor please share.
- Intakes: Correct based on what I have experienced. Road race (and the drag race ‘DRAG’ stamped retail intakes) Didn’t get PCV, water temperature sensor, or heater hose ports drilled. Those ports weren’t needed.
- Valve covers: Correct. I over-looked the obvious, sorry. SAI started modifying O.E. steel valve covers almost as soon as the first Cobra hit the race track. There were several versions done in different time frames. I suspect that most later differences were due to who made them up. I have a few copies SAI race shop drawings and it is instantly clear there is not enough information on the drawings to be able to recreate parts from. The drawings that I have copies are more like guidelines. Fabricators did what they needed to get the job done. Dave Friedman published a picture of the engine in CSX2323 in Europe in early 1964 that shows valve covers modified into what has become known as “GT350R” covers long before the first GT350 was even dreamed of.
- Electric fuel pump(s): Correct but not really part of the engine. The standard practice for most SAI race cars 1963-65 was to use one or more electric pumps near the fuel tank to push fuel forward to O.E. mechanical pumps on the engines. This use to be a very common practice for all kinds of competition cars no matter who built them if the sanctioning body rules required the used on ‘stock’ fuel pumps. The legendary ‘FIA’ team Cobras that raced the world’s best still had plain Fairlane mechanical fuel pumps on their engines in 1965 based on old photos.
- Camshaft(s): Oops, another obvious miss on my part. Unsubstantiated legends are all that I know but old magazine articles from the period indicated than Engle® custom ground camshafts for SAI depending on what they wanted at the time of order. “Shelby” camshafts are very confusing as between 1963 and 1970 so many different grinds were offered through the SAI/Ford parts program. I have a spreadsheet where I have collected published data by retail part number or Ford part number. My list has eight (
different grinds under seventeen (17) different part numbers. Example, the O.E. HP289 grind is listed these different ways
C3OZ-6250-C Ford
S1CR-6250-D (GT350 street) Shelby
93219 Shelby/Honest Charlie 1967½ road race
GFJD-6250-A Shelby road race
FBE-1225-B Moon 1968 road race
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Edited by - csx4781 on 02/19/2010 00:05:16