- Nov 15, 2010
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Moper if I heard and understood you correctly you're say that even with brand new pistons, rings and all the goodies if i rebuild stock, I'll still be sitting at a low cylinder compression and low overall low compression. Now changing from flat top pistons to a different style and cam upgrade with heads would increase my overall compression correct?
The issue is the block. not rods, pistons, cranks, gaskets, etc. Factory 383 blocks are all tall. Some very tall. Factory chambers (big open and closed versions) are as-originally-assembled normally larger than the published specs. Add a valve job or two in the eons since it was first bought and the chamber sizes get even larger. To get a real "10.5:1" or even a true 9.5:1 with any factory head takes blueprinting the block and the heads to remove the extra height and the extra volume respectively. Even with domed "shelf part number" pistons. No flat top will be anywhere near 10:1. If your engine has a stock 2bbl piston, a composite head gasket, and the least and lowest budget machine work done during the rebuild, I would be shocked if it's over 8.2:1 when measured and calculated. Most guys didn't do this in years past because the milling was heavy requiring multiple passes, cost more money, Mopar decks are usually pretty flat with the 17 head bolts used, and the operation when done on the old-school equipment removes all stamped numbers from the ID pad on a B wedge. Modern machining centers can do the blueprinting and retain the numbers.
PS - all the issues will effect any stroker combo based on the B wedge block too. So if you want the correct compression ratio the block has to be blueprinted.