My compression test results
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Laughing Gas
Joined: Oct 2013
Posts: 947
Likes: 6
From: Manitoba, Canada
My compression test results
68 FE360. 109,000 miles. I only warmed the engine a bit, maybe two minutes. This is what I got:
Front
100 105
107 107
107 110
100 105
Rear
Any opinions on these numbers because I don't have a clue.
Front
100 105
107 107
107 110
100 105
Rear
Any opinions on these numbers because I don't have a clue.
Postmaster
Joined: Nov 2012
Posts: 2,806
Likes: 8
From: Langley, BC
You ideally want the engine at normal operating temperature, so two minutes could've been not enough. But, the readings are consistent and that's really what you're going for. They're not as high as I would like them to be but it seems like the engine is just a little aged. Is it completely stock? Are you noticing a lack of power?
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
That, and the carb butterflies have to be full throttle wide open. All spark plugs removed. Fully warmed up, half hour at highway speed? Fully charged battery, good serviceable starter running at crank RPM spec. Dry test, then wet test, avg of the highest of at least two runs per cylinder, etc.
Compression test is a bit more complicated than it seems for accurate result. Those numbers don't look too bad considering. Mentioned in another thread, a vacuum gauge connected to manifold will indicate engine compression indirectly, and a whole lot more, with a lot less hassle. If engine draws 18, 19 or 20 inches steady then the compression is fine. A proper compression test itself is awful hard on the starter and battery imo.
Compression test is a bit more complicated than it seems for accurate result. Those numbers don't look too bad considering. Mentioned in another thread, a vacuum gauge connected to manifold will indicate engine compression indirectly, and a whole lot more, with a lot less hassle. If engine draws 18, 19 or 20 inches steady then the compression is fine. A proper compression test itself is awful hard on the starter and battery imo.
Thread Starter
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Laughing Gas
Joined: Oct 2013
Posts: 947
Likes: 6
From: Manitoba, Canada
.
It's stock and it's a project and it's not licenced for the road yet but I've driven it around the neighborhood a few times. I've got it all tuned up and it runs pretty good. Starts right up, idles good after warm up and revs up okay with no hesitation but when I drove it will fart at the carb a bit if I try anything beyond 1/2 pedal acceleration. Plan is body work and paint the exterior first. Phase two will be replace the tired drivetrain.
Postmaster
Joined: Nov 2012
Posts: 2,806
Likes: 8
From: Langley, BC
It's stock and it's a project and it's not licenced for the road yet but I've driven it around the neighborhood a few times. I've got it all tuned up and it runs pretty good. Starts right up, idles good after warm up and revs up okay with no hesitation but when I drove it will fart at the carb a bit if I try anything beyond 1/2 pedal acceleration. Plan is body work and paint the exterior first. Phase two will be replace the tired drivetrain.
Postmaster
Joined: Nov 2012
Posts: 2,806
Likes: 8
From: Langley, BC
It's a '68 though. The 390 of that year was 9.5:1. I doubt the 360 would be too far off. Maybe 8.5? Not terribly low.
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Logistics Pro
Joined: Jan 2011
Posts: 4,762
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From: Antelope Valley ,CA
TO my knowledge the truck 360/390 had 8.1 ish C/R the passenger car had 9.5-10.C/R year didn't matter
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Cargo Master
Joined: Apr 2001
Posts: 2,697
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From: Vancouver
I don't feel comfortable saying this to you, but I think 100 psi indicates a worn-out motor. Probably rings/cylinders; it it were valves the numbers would not be so consistent. A wet test might confirm my opinion. My wheezy 352 is 130 across and should be 150+ the experts tell me.
Eric
Eric
Post Fiend
Joined: Apr 2002
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From: Waterloo, Iowa
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