re: Compression

[farna@xxxxxxx]

"Normal" compression varies with the engine. A 1978 232 should have 140 psi, a 258 150 psi... NEW. The 82 TSM states 120-150 for the 258. I believe that's pressure measured with the engine warmed up. Before you get scared, 95-100 psi is still good. Should be no more than 10 psi variance between adjacent cylinders, 30 psi from highest to lowest. 

If you read 85 psi across the board, you're probably still good, and likely measured cold. You can also put a squirt of oil in the plug hole and measure compression. That should increase it just about the same as if the engine is warm. As it warms up some oil gets to the rings and helps sealing, dry rings don't seal good. 

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original message----------------------------------------------

Date: Sat, 11 Feb 2006 16:58:34 -0600
From: Todd Tomason <jayscore@xxxxxxxxxxxxx>
Subject: Compression

What is normal for compression, anyway?  I did a compression test on my 258 in 
my Spirit a while back, and it was about 95 lb. on each cylinder.  Is that 
normal or low?

Todd