i got lt1 heads that are ported and shaved 10 thou what would the combustion chamber cc be approx?

what are the stock cc?

at 56cc my motor will be 12.09:1 compression

 

I just got mine back from AI. I wanted 52 cc chambers so Phil decked them .014. Chambers are now 52.3 cc

 

stock lt1 heads are 58 cc, so your compression will be under 11.9, but i think on pump gas your still screwed

 

If they are, how could sleeper's have been more like 54 1/2 cc? (1cc to appr. .007") Remember, his were actually checked. While many may check out 57-58 oem, the specs are actually 54 cc for LT1. ( Or is it 54.4 cc? ) Anyway, to blanket ALL LT1 heads as being 58cc without an asterick would be misleading.

 

with 58cc my compression is

11.78:1

 

I have always heard LT1 heads are either 53 or 54cc. How can there be this much difference in cc? I can understand the 53 or 54 but range from 53-58???????????

 

Just cuz someone posts figures, doesn't make them accurate.

......but range from 53-58?

Consider that the range of ACCURACY of various posts.

However, (and this has been posted several times here) oem blocks AND heads are assembled with extra stock on their respective surfaces. Figure .015-.020" on average. Without exception? No, but in a small minority.

I edited this post to rephrase one sentence to make my point more clearly understood. By that I should have stated that is the range of INACCURACY of various posts. My range would be from 54, (which is unlikely) to 57 1/2 (with .020" extra stock on head).

 

It's not 58cc. I've always used 54cc for a good starting point, but, measuring is always best.

Many cars on this board(mine included) have run mid 11:1 compression on pump gas with no problem. Over 12 is pushing your luck though.

 

That starting point that you state you use; I'm interested in knowing whether you have achieved that figure with accurate measuring, or is your starting point just a estimate/guess? Also, are you measuring the various volumes accurately to arrive at the 'mid 11:1' ratio, or again, is that an estimate?

 

52.5cc with .010" milled off, .029" Impy head gaskets and 11.4:1 compression. I do know how to figure out a compression ratio, but thanks.