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Old 10-14-2012, 07:20 PM
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Quote:
Originally Posted by TommyK View Post
Yes the 72 D2VE heads are a one year only open chamber head which is detonation prone. I would strongly suggest finding a pair of early small chamber castings C8, C9, D0 or D1 closed chamber heads. Assuming you have a stock 72 bottom end this will raise your static compression ratio to approximately 9:1. D3 heads will work as well but they are large chamber and your compression will be 8:1 or less
Let's put some real numbers together. Lets assume a stock bore and stroke of 4.360" x 3.850". Further, lets assume that heads 1968 through 1971 were approximately 75 cc's and that heads 1972 and later were approximately 95 cc's. The 1972 D2VE heads were junk, so we'll throw them out. 1973 and later D3VE heads were OK.
Let's figure some static compression ratios just for grins....

Using early heads (75cc)
Cylinder volume (.7854) x 4.36 x 4.36 x 3.85 x 16.387 = 942 cc's
Chamber volume 75 cc's
Piston deck height volume (figured at 0.060" because of increased block deck height of 1972 and later blocks....(.7854) x 4.36 x 4.36 x .06 x 16.387 =15 cc's
Piston crown valve reliefs....estimate at 10 cc's
Head gasket....estimate at 10 cc's
942 + 75 + 15 + 10 +10 = 1,052 cc's
75 + 15 + 10 +10 = 110 cc's
Divide the larger by the smaller and find 9.56:1 SCR

Using later heads (95cc)
942 + 95 + 15 +10 +10 = 1,072 cc's
95 + 15 + 10 +10 = 130 cc's
Divide the larger by the smaller and find 8.25:1 SCR

So there is about 1 1/4 points of SCR between the early and the late heads on a stock bore and stroke 460.

If I were going to run the motor without tearing it down for a rebuild and correcting the horrible piston deck height and squish, I would use the later heads and a very short cam or the stock cam. That would allow the motor to operate well on junk pump gas without detonation. I'd be afraid of running 9.56:1, particularly with a short or stock cam. Of course, you could use a longer cam that would bleed off some of the cylinder pressure and make the motor less prone to detonation with with 9.56:1 SCR, but what I'm understanding here is that the OP has little or no expertise in that area.

So, bottom line, leave the cam alone and run the 95cc heads would be my advice.
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