Low compression in first cyl
 

Im going to go check out this truck tommorow,what should I know about this low compression issue. Sorry im a tech idiot.
Is it somthing to be really concerned about? rings ? head? valves ?


72 GMC PU, <3/4>T, 350 4bbl, V8, reblt eng, 100,000 orig mi, orig owner, maint, new pts installed, have all rcpts for past 4 yrs, runs gd, low compression in first cyl

My uncle and I found out one of my cylinders was missing. We took out that plug and hooked up a pressure guage. It was only putting out around 58psi.

He squirted some oil (not motor oil) into the cylinder. He said that if the pressure goes back up to normal, then it's the rings. If it stays the same, then it's the valves. Well, mine stayed the same. So I guess I just need a valve job. At least I don't have to tear apart the motor and replace rings!

The cylinder misses around idle, but it starts firing when I pick up speed and the compression builds.

yes you are correct. if you squirt oil into the cylinder and the compression does not get better then it is the valves. you can use any kind of oil, heck even tranny fluid will work. I would use something like a straight 30wt oil so it is good and thick.

Nathan