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'73-'87 stock compression

22K views 9 replies 4 participants last post by  79Bird466 
#1 ·
I punched the numbers into the C/R calc and got about 7.85:1. Is that about right? I have always seen the ratio listed as 8:1...is that just a rounded figure? This is for a 10.322 deck with stock D3VE (95cc) heads, 22cc dish piston and a .041 head gasket. Do all these numbers look accurate for a stock smogger?
 
#2 ·
72' was 8.5.1 So I think it was close....
 
#5 ·
Did the '72s use flat tops or did the D2VE heads have smaller chambers? or neither?
 
#4 ·
Scary part is in 71' they were 10.5.1!!!!!!

Sheesh!
 
#6 ·
Actual real world comrpession ratio for the 1973-1986 engines is about 7.7:1, and possibly less depending on actual cylinder block deck height (which varies from block to block by several thou) and acutal combustion chamber volume (which also varies).

Paul
 
#7 ·
Paul is right.... looking at my books that is true. The 73's were about 7.5.1 in all actuallity.

Here.... this might help a little...

 
#8 · (Edited)
I think the calculator is a bit off. I just entered the specs given from that book for a '72 460 and came up with 8.06:1. I even used the high end of the chamber size range (92.9cc) ...I'm assuming they used the same pistons as '73-'87 (-22cc)
 
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