Correct way/pressure check
Thread Starter
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Senior User
Joined: Oct 2003
Posts: 188
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From: Miami, FL.
Correct way/pressure check
Anybody know the correct procedure to do a compression check on a 351W?
I see different instructions everywhere I look; some say take out one plug, some say take out all the plugs, and so on.
TIA,
Munrow
I see different instructions everywhere I look; some say take out one plug, some say take out all the plugs, and so on.
TIA,
Munrow
Elder User
Joined: Jan 2004
Posts: 561
Likes: 0
From: houston
This is the way I recommend doing it. Take all plugs out. If it is carburated, prop the carb open. I do this so there is no flow restriction. Then I crank the engine over 4-6 times. However many times you crank it over is up to you, but make sure you do it the same number of times for each cylinder. You will hear the engine cycle every time the cylinder you are testing comes around to it's compression stroke. When you have done all cylinders, compare the readings. If you have some low readings, squirt some light oil into each one and crank the engine over a few times to distribute the oil on the rings and go thur it again. If the compression comes up on the bad ones you have worn rings. If it stays about the same, you have burned valves. Oh, if it is F.I. I use a jumper across the solinoid to crank the engine. This way you don't have the fuel system putting fule into the cylinders during the test. Good luck.
Thread Starter
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Senior User
Joined: Oct 2003
Posts: 188
Likes: 0
From: Miami, FL.
Thanks for the reply. Been away for a while and haven't been checking.
Seems taking all the plugs out at the same would be the best way. Way more efficient at the least.
Thanks again, Munrow
Seems taking all the plugs out at the same would be the best way. Way more efficient at the least.
Thanks again, Munrow
