Stock Compression
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Fleet Mechanic
Joined: May 2004
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From: Montana
Stock Compression
In a 92 351 what is the stock compression?....8.5:1? and what size is the combustion chamber in the stock heads? Im just doing some calculations for my motor, trying to choose pistons, heads and such.
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From: maui.HI
Egoman, I think you're right about it being 8.5:1. I posted this same question about a year ago in the E series van forum and one member mentioned 65 or 67cc on the heads but I can't be sure. He did mention that the compression wasn't that great because of the dish pistons.
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i just rebuilt a 351 w with e7tes and it has 9to1 comp its a 1986 351w and it did not have e7te heads on it i got them from another engine
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Fleet Mechanic
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From: Montana
Do you know what pistons and the P/N you used? I wanna try to get 9.5:1 if its possible but most pistons are giving me like 10'ish or like 8.8:1....
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From: south louisiana
I looked in Silvolite's site and they offered three basic designs for 351's, one was the flat top with about a 10.5 to 1 ratio, then the Lightning replacements that were 8.8 to 1 and then the std late 351's were around 8 to 1. The flat tops will get you close to a 9.5 to 1 ratio, but with big chambered heads, which kind of defeats your purpose, you get the ratio you want but lose some detonation resistence with the larger chambers. Probably the best compromise would be the Lightning pistons with smaller chambered heads ( 58cc instead of 64's)
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Fleet Mechanic
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From: Montana
Well I was lookin at the 60cc edelbrocks...I was thinking about a set of TRW forged pistons H336P 30
they say there 9.4:1 or about that..I figure with a .038 headgasket. But If I do my calculations with those numbers my figure comes out alot lower.
they say there 9.4:1 or about that..I figure with a .038 headgasket. But If I do my calculations with those numbers my figure comes out alot lower.
Last edited by EgoMan; Apr 2, 2006 at 01:12 PM.
Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
Your compression depends on the type of piston being used, the piston to deck height, the thickness of head gasket, the combustion chamber volume, the bore and the stroke.
You can find compression calculators online...
You can find compression calculators online...
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Joined: May 2003
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From: south louisiana
Originally Posted by EgoMan
Well I was lookin at the 60cc edelbrocks...I was thinking about a set of TRW forged pistons H336P 30
they say there 9.4:1 or about that..I figure with a .038 headgasket. But If I do my calculations with those numbers my figure comes out alot lower.
they say there 9.4:1 or about that..I figure with a .038 headgasket. But If I do my calculations with those numbers my figure comes out alot lower.
Hotshot
Joined: May 2003
Posts: 11,141
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From: south louisiana
Originally Posted by EgoMan
Well I was lookin at the 60cc edelbrocks...I was thinking about a set of TRW forged pistons H336P 30
they say there 9.4:1 or about that..I figure with a .038 headgasket. But If I do my calculations with those numbers my figure comes out alot lower.
they say there 9.4:1 or about that..I figure with a .038 headgasket. But If I do my calculations with those numbers my figure comes out alot lower.
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Fleet Mechanic
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From: Montana
Originally Posted by MustangGT221
Your compression depends on the type of piston being used, the piston to deck height, the thickness of head gasket, the combustion chamber volume, the bore and the stroke.
You can find compression calculators online...
You can find compression calculators online...
My deck was 1.75throw+5.956Rod+1.772Piston-9.503 = 9.478(.025) I think anyways... 60cc heads...i was using .038 inch gaskets dont remember the make, but gasket bore was 4.1". Thats how I came up with 9.1:1.
Now I do have a set of pistons that would bump me up into the mid to low 10 range but I dont know how this speed density will handle that? I had another post but nobody seems to know.
Last edited by EgoMan; Apr 2, 2006 at 04:43 PM.
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From: western montana
it's kind of weird...on the 335 series forum there are numerous engine builders and enthusiasts- specs come very easy with several very specific build plans...you trip over them when searching...thats with engines that hasn't a following as compared to windsors. I think it's similar with the fe's
here it's like pulling teeth to get any spec let alone build recipies(sp?). I ordered a dvd that might help and will look for another source...spent hours searching posts- maybe some one ougt to be commissioned to publish a spec and build thread or something to get the juices flowing???
here it's like pulling teeth to get any spec let alone build recipies(sp?). I ordered a dvd that might help and will look for another source...spent hours searching posts- maybe some one ougt to be commissioned to publish a spec and build thread or something to get the juices flowing???