Re: cranking compression question
[Re: gch]
#1481769
08/08/13 10:07 PM
08/08/13 10:07 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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I'd be comfortable with 140 give or take 10 either way & happy with 150 or more. Critical is that there are no low ones
live every 24 hour block of time like it's your last day on earth
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Re: cranking compression question
[Re: gch]
#1481773
08/08/13 11:41 PM
08/08/13 11:41 PM
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Joined: Jan 2003
Posts: 15,498 Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,498
Omaha Ne
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Quote:
The cylinders are all within 10 psi but the numbers are a LOT lower.I was thinking 120 at best with that low of a compression but all are between 80-90.
80 to 90???? Ouch!!!! it will run but will have its tail between its legs,
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Re: cranking compression question
[Re: gch]
#1481775
08/09/13 12:56 AM
08/09/13 12:56 AM
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Joined: Jun 2012
Posts: 1,899 MYRTLE BEACH SOUTH CAROLINA
ek3
top fuel
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top fuel
Joined: Jun 2012
Posts: 1,899
MYRTLE BEACH SOUTH CAROLINA
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Quote:
On a low comp 440(75 model 8.2-1 advertised)what would be a good cranking compression number? The motor was cold and the cylinders dry.
100 lbs. will work fine. you would be surprised what just a good valve job or a new timing chain would do. warm it up, pull all the plugs out, and spin it over 3-4 times to test. when you warm it up , run a little marvel mystery oil in it also then re-check it. a good fresh 440 with 8 -1 compression making 130-40 lbs. would run fine. if you are looking for real power , 9:5:1 or better and 175 + is a good starting point. if the engine has set up for a long time, while running it, pour a little diesel fuel [ about a quart untill gone] in the carb when it is hot and revved up some . this will free the rings / valves up .
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Re: cranking compression question
[Re: AndyF]
#1481776
08/09/13 01:27 AM
08/09/13 01:27 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
Striving for excellence
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Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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Quote:
I checked the cranking compression on my stroker motor the other day and it was 235 psi. And that is with a 280 at 0.050 camshaft. I can barely turn the engine over with a cheater bar.
Holy crap! Thats a RACE fuel engine for sure! I was at 190 in my 440/493. 10.7 static with the MP '509 cam.
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Re: cranking compression question
[Re: Kern Dog]
#1481786
08/09/13 04:45 PM
08/09/13 04:45 PM
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Joined: Jul 2006
Posts: 4,179 California
mickm
master
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master
Joined: Jul 2006
Posts: 4,179
California
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Quote:
Quote:
I checked the cranking compression on my stroker motor the other day and it was 235 psi. And that is with a 280 at 0.050 camshaft. I can barely turn the engine over with a cheater bar.
Holy crap! Thats a RACE fuel engine for sure! I was at 190 in my 440/493. 10.7 static with the MP '509 cam.
the new engine is 210 on every cylinder, and runs fine on 91. but i guess 25 more is a lot. same thing for me, tying to turn it over with a breaker bar is an exercise in upper body strength.
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