516 heads

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stroker mike

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Can 516 heads have the exhaust valve and port bored out to the same size as a 915? The bigger exhaust valve would be a huge improvement, and with the closed chamber I could achieve a good quench.. I have some 915's that were decked too much, with my setup. I got kb flattops and I'd end up with 10.2:1. Too much for a street build, I'm running a xe275hl cam, I was shooting for 9.25-9.5. So since I already had the block decked to zero I thought if I can find some untouched 516's and get a 1.74 exhaust valve in there it would be the same but I'd get my 9.5. ??
 
10.2 would be fine if you have a good quench? block the heat to the manifold, and can get 92 or 3 octain. 516's are good for a stock to mild 383 but i wouldn't use them on anything bigger, your using a bigger cam so the important thing is the cranking psi and not the static number of 10.2
 
The 516 flows less than the 906 heads on the intake with the same size valve, so there's more than just the smaller exhaust valve.
 
It can be done. As said, the port needs to be shaped a little better. But on your build... 10.2 is fine with that cam. You just wouldnt want to go much smaller. You will not have ping problems if it's properly tuned. I've run similar cams at 10.6:1 with no issues. In fact, the engine I'm thinking of has 516s with 2.14/1.74s in it and makes 475hp on pump 92.
 
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