Quote:
Originally Posted by Dean Feiock
I am going to use my motor as an example. I own many sets of 416 heads. And I can tell you that there are several different bowl shapes, straight from the factory. There are several sets that have a secondary cut in the bowl in additition to the factory bowl cut. Personally, I believe these were heads that were cast for a 1.72 valve and were opened up at the factory to accept a 1.84 valve as they needed them.
So which head would you use as a model?
I am told at a recent race, they pulled down three 305 motors. And I am told that all three heads looked different.
So how do you decide which head was wrong?
I don't want to speak for Wade, but I think his concern is simple. We have been given runner volumes. If we meet those volumes, all other measured items pass, and there are no grinding marks in our runners, shouldn't the head pass tech? At least that is the assumption many were under.
You say buy a digitizer. I say NHRA would need 8-9 of them minimum. And then they would need to train on how to use them. And then "which" head do you use as model?
I don't envy NHRA tech. We are a big pain in the a**. They work hard when we are having fun. We bitch when they do their job and we bitch when they don't.
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You are correct, the OEM's used the same castings for different applications were they changed the valve sizes and many times the chambers too. Also, you can add core shift issue on thin late model castings and the diverse foundries used for castings.
The problem in using a digitizer is that you will need to do statistical analysis to get a measurement that would cover the variation in the casting. Besides, NHRA will not invest in such equipment either.
Just think the variations they already have on the burrettes due to the differences of material and manufacturer.