Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
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Only true way is to measure all the parts you plan on putting together. Advertised volumes for relief pistons and heads will vary compared to actual. Difference may be negligable though - maybe somebody else can chime in.
Stock 350 bore is 4 inches. Was your block bored to get 357 cubic inches? How much overbore? You will need to enter this larger bore diameter.
Any reason for going with steel shim? Composite gaskets fit better to slight deck uneveness with block and heads. You also need to determine quench area. Ideal is 0.04 inches. I believe composite gasket helps here too as you can get different thickness gaskets for ideal quench. Links below on quench and compression.
you will need to find out how far below the deck the pistons sit and the valve relief volume but i wouldnt count on anything more than 9.0:1 with those heads and say 7-12CC pistons and
and your right attilla most of the 4 valve relief flat tops add 6cc or less
how ever every stock replacement with 4 valve reliefs also only have a compression distance of 1.540 instead of 1.560/1.565 so six of one half dozen of the other
adding the "extra" .020 to the distance below deck brings you back to 8.8:1 with 6cc valve reliefs
and your right attilla most of the 4 valve relief flat tops add 6cc or less
how ever every stock replacement with 4 valve reliefs also only have a compression distance of 1.540 instead of 1.560/1.565 so six of one half dozen of the other
adding the "extra" .020 to the distance below deck brings you back to 8.8:1 with 6cc valve reliefs
This is NOT true. I handle a half dozen sets of these every week, and I do have to check some sets, but the Silv-O-Lites and the SpeedPros are all 1.560", even their cheapest "claimer" versions. So these are what I push, and I imagine most other reputable shops do the same.
This is why I asked becuse even with the calculator I was way off.
So my new heads should be 64cc to bump up my compression correct?
Then I will figure out what converter I need.
What would CR be with the 64cc heads if nothing else changes?
If your pistons aren't too far in the hole, and you can get your piston-to-head to around .040", where it should be, you should then be around 10.3:1. That's fine with aluminum heads.
all 1.540 stock replacement cast 4 valve reliefs and 1.540 comp height
stop trying to use your job to prove your right because you "handle half a dozen sets of these every week" doesn't mean you have a clue about what your saying
Typo's are common. My own measurements are all I care about. And on every single set of Silv-O-Lite hypers, including their "claimer" s, and every single set of H345NCPs, I've found at least 1.559". You want to argue and become famous and respected, this guy just wants info he can use, you dumb armchair warrior, hiding behind your keyboard. Go away. To the OP: Here's the info you can use: Pull the head, and measure how far down your pistons are at TDC. Then we can go from there.
I bought it from the guy who bought it from the guy who had the short block re-built so I apparently do not have all the info I need to figure this out.
I won't be pulling the heads till the season is over.
At least now I now I can go with the 64cc and still be around 10:1,I don't want to go higher than 11:1.
And the converter will have to wait till I figure this out.
