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Old 01-12-2013, 06:10 AM
cdminter59 cdminter59 is offline
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Finishing up BBC build quench and dynamic compression questions

First unless you have the correct figures everything is a guess. Assume that the 820 heads have 113cc chambers and the pistons are .015 down in the block. Using a .027 compressed thickness head gasket, a 4.375 gasket bore, and 44+15=59 for intake closing point. Your static compression would be 10.561 and the DCR would be 8.826. I am sure you would hear detonation with these figures. On a BBC you don't want to go over appoximately 9.6 static compression with iron heads.The DCR should be in the range of 7.5-8.5 for 91 octane gas. One option to lower the compression is to machine the dome to .016 which will lower the compression to 9.705 and DCR to 8.125. Like I said this is guessing until you cc the heads and measure how much the pistons are down in the hole. BTW I am using the KB compression calculator. http://www.kb-silvolite.com/calc.php?action=comp
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