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 Blocks / Cranks/ Rods and Pistons
 455 with 6X-8 comp ratio ??
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jrunner
Tribal Scout

USA
13 Posts

Posted - 10 Feb 2014 :  04:56:47 AM  Show Profile  Reply with Quote
Can someone please confirm that with a 455 with a flat top trw speed pro piston and 6X-8 cylinder heads I will have approx- cr of 9 to 9-1/2cr?? Thanks.

Edited by - jrunner on 10 Feb 2014 05:00:36 AM

Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 10 Feb 2014 :  11:09:00 AM  Show Profile  Reply with Quote
Depends on how far the pistons end up down in the hole at TDC. And the final CC of the cylinder heads after valve job and milling. Average numbers show it at 9 to 1.
http://www.wallaceracing.com/cr_test2.php


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Mr. P-Body
Running Bear

USA
2258 Posts

Posted - 11 Feb 2014 :  8:32:41 PM  Show Profile  Visit Mr. P-Body's Homepage  Reply with Quote

With a typical flat-top piston, a 98 CC chamber will yield right at 9.3:1 with a .040" gasket (actually 1 mm, but I won't quiblle over a couple tenths of a thousandth in the head gasket). and .010" deck clearance. Makes a nice, pump-gas friendly (92 or 93) setup you can make some serious power with, depending on just how "far" you take everything else.

6X-4 heads are popular among some on the 460-ish engines. I prefer the larger chamber. No need to push limits unless you're racing in a specific class where every inch-ounce "counts".

FWIW

Jim

Edited by - Mr. P-Body on 11 Feb 2014 8:33:02 PM
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