Rebuilding 327 - Compression Ratio?
Thread Starter
Racer
Joined: Aug 2005
Posts: 355
Likes: 1
From: Ephrata PA
Rebuilding 327 - Compression Ratio?
I will be rebuilding my 327/350 and would like to know what the consensus is on a decent compression ratio. Do I use the original style 11-1 popups or should I go to a flat top and get the higher ratio by using a tighter chambered head? I thought I read somewhere that you get better combustion across a flat top piston. Any opinions welcome.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
You heard right. Flat-tops are more efficient. With a cast iron head, limit the combustion chambers to 64cc's, yeilding about 10:1. Modern designs used in today's heads will more than make up for the 1 point c.r./hp. loss.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
Originally Posted by dmentzer
I will be rebuilding my 327/350 and would like to know what the consensus is on a decent compression ratio. Do I use the original style 11-1 popups or should I go to a flat top and get the higher ratio by using a tighter chambered head? I thought I read somewhere that you get better combustion across a flat top piston. Any opinions welcome.
BTW ... 58cc heads, 2vr flattops & 3.75" stroke crank (400) will net you an easy 11:1 ... and it'll be a 383" stroker. If your 327 has small journals ... 350-400 journals can be ground smaller.
-edit- IMHO ... 9.5:1 - 10:1 is nice CR for street.
Chevy 305 (305) iron heads from late 70s thru 86 will fit ... they're 58cc ... plenty of em around cheap. World products P/N 0452650-1 is also bolt-on iron 58cc ... about $600/pr new complete ready to go.
Last edited by jackson; Nov 25, 2005 at 04:39 PM.
