SS Ford question
 

Ok, so I am putting together this GT/MA deal for next year, one problem is the engine I am using does NOT have a carb on it. It is a 68 Mercury 302, and I am lost reading the Bluprint specs on the carb. It says it is a holley but what numbers? I have a regular 1850 carb sitting here will that work? We have the right heads and everything else it seems. The only other question I have is on the pistons, they are Ford .030 over pistons but they are not listed on the replacement piston list or is that list only for aftermarket replacements?

Sorry to be asking such questions, but I really dont want to get to a race and get told my car is not legal.

Thanks in advance..

And Happy Holidays to everyone..

Re: SS Ford question
 

In the engine spec for the 68 Ford the entry for the 302/320 Comet & Cougar it says you can use a Holley carb and there are some Ford P/N's. There is also a reference to note 15. If you look at note 15 in the Carb Specs it says:
15 - 1563x1563/1250x1313

What that means is that the allowable carb has a primary and secondary throttle bore of 1.563" (which is 1 9/16"). The primary venturi size is 1.250" (1 1/4") and the secondary venturi is 1.313" (1 5/16").

So any Holley carb that has those throttle bores and venturi sizes, and is the correct model (4150 in this case) and has the proper fuel bowls (center pivot "cathedral" type in this case) and has the choke horn and choke blade in place (can be wired open), is ligit.

Essentially, those throttle bore and venturi sizes are used on most Holley 600 CFM carbs. There are some variations on the booster venturi's on various carbs, but NHRA doesn't care about those. As long as it is the correct model, throttle bore and venturi size, and has the choke junk, you can use it.

You could use an 1850 body, convert the secondary metering plate to a metering body (4160 to 4150 conversion) and use center pivot bowls and it would be ligit.

If you have FoMoCo 0.030 pistons for that engine then they are legal. Don't have to be on any list except for FoMoCo's. Those are cast pistons aren't they? Not so sure you want to use them in a S/S engine. Your likely going to have to cut some pretty significant valve clearances on them for a big cam. Doesn't sound very durable.

Re: SS Ford question
 

Bill: the pistons are forged. So if I read the carb thing right my 650DP may fit the criteria as well... SWEEET... Spent the better part of the day at the engine shop, we are hopeful to get this in the car and running by the last week af January, so i will have at least a week to test before the first Div 2 race.

Re: SS Ford question
 

Nope, double pumper isn't legal. It has to have vaccum secondaries like the OEM. You could force the secondaries open with the old screw in the slot routine, but the secondary diaphram and linkage has to be intact.

Re: SS Ford question
 

I was not aware that SS pistons were on a list only stock or am I missing something on the NHRA site?

Re: SS Ford question
 

David, the way I read it the engine section builds from the Stock section, so i automaticly figured they had to be the same pistons.

Re: SS Ford question
 

Actually, SS has it's own piston rule section and it is pretty liberal. You can do pretty much anything you want as long as the piston top is the same configuration as OEM and it doesn't do anything to increase the compression ratio. In most cases, the compression ratio will be less since the valve reliefs will have to be deeper than OEM due to the high lift cam. Stock has to have the OEM ring pack and placement as well as the OEM top configuration and volume. I think most all-out SS engines use very light pistons with only one narrow or high tech style compression ring and a narrow low-drag oil ring. They might look like the OEM from the top of the motor, but you would never mistake one for OEM if it were sitting on the bench.
That being said, an OEM piston should be perfectly legal, just not as trick as it could be.