Compression in lbs per sq in?

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Aug 9, 2008 | 01:29 PM

dfolse62

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Pro

Joined: May 2005

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From: Shreveport Louisiana LSU

Compression in lbs per sq in?

Recently rebuilt engine. 400 CI. I am not sure of the final compression ratio, but the engine sort of sounds like a diesel, just more noise than I like. I don't know what to check next. I did run a compression check this morning. On one older gauge (holding it in by hand) it showed to be about 132. With a gauge with better rubber (still holding in by hand), it showed at just over 140 lbs! Is this high? Thanks!!

Aug 9, 2008 | 02:24 PM

Retro78

Drifting

Joined: Oct 2004

Posts: 1,259

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From: Ontario

Without knowing more about your engine build, the actual number is meaningless. But no that is not too high. Measure all 8 cylinders and look for differences between them.

Aug 9, 2008 | 06:20 PM

billla

Le Mans Master

Joined: Jun 2004

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From: Seattle WA

St. Jude Donor '14

Let's back up for a second - it's clattering like a diesel, even at idle?? First thing that comes to my mind is valve adjustment!

Aug 9, 2008 | 07:00 PM

dfolse62

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Joined: May 2005

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From: Shreveport Louisiana LSU

I'm sorry I can't give more details until tomorrow. It is a bored out 400. Flat top pistons with eyebrows for valve clearance, 486X heads. New Comp cam and lifters. Hydraulic. The valves were set before initial crank up. I then set them while running. No noise here. It seems to be more internal. I will know more tomorrow as a motor builder is looking at it. I don't know if it is pre ignition, piston skirt slap, or what. It just sounds like crap. Runs good!! Just sounds like a John Deere. Make that an International Harvester hay baler.