Major 1988 360 problem... help!

scrible88

:razz: Well I lost my #1 cylinder a little while back so I unplugged the spark plug wire so it wouldn't fire, the exhaust valve was not opening and the exhaust gasses were backfiring up through the carb... Well I thought the lifter had messed itself up so I pulled the intake and valve covers today and bought a full set of lifters, I thought it would be better to replace them all. When I pulled the exhaust valve lifter for the #1 cylinder I didn't look at it too closely and put the new lifter in. I turned the motor over by hand and the valve was still not opening... it was stationary... I took a closer look at the old lifter I pulled out and it shocked me. The bottom of it (towards the cam) was worn like a bowl from the cam lobe, so deep there was a hole in the bottom of the lifter... I am able to slightly compress the intake #1 valve spring by putting enough force on it, but the exhaust valve spring is solid, can't move it at all... So... what the hell could have caused this? Why would that valve be stuck? I really don't want to pull the heads or anything but I am fearing I will have to. Do you think the cam lobe is wiped? I'm betting it is pretty well worn considering it tore the heck out of the bottom of that lifter. Please help! The motor is all stock other than the intake and carb and this is the first time it has really been taken apart this far... :shock:

82Waggy

Sounds like it is time for a valve job and cam to me.

tufcj

Usually seated valve pressure is around 90 LBS. A lot more than you should be able to move with your hand. My bet is the valve that you can move has a bad spring (intake). The engine vacuum is sucking that open, causing your backfire. If the lifter is dished, the lobe on the cam is trash, so it's time for a new cam/lifters. DO NOT use the new lifters you have on a new cam, UNLESS it's NEVER been started. Even a few minutes of run time will have put enough wear on those lifters to make them eat another cam. Valve job with new valve springs, cam, lifters, timing chain and gears are in your future. Bob tufcj

FuzzFace2

Yep what they said :smile: Dave ----

scrible88

tufcj wrote
Usually seated valve pressure is around 90 LBS. A lot more than you should be able to move with your hand. My bet is the valve that you can move has a bad spring (intake). The engine vacuum is sucking that open, causing your backfire.

If the lifter is dished, the lobe on the cam is trash, so it's time for a new cam/lifters. DO NOT use the new lifters you have on a new cam, UNLESS it's NEVER been started. Even a few minutes of run time will have put enough wear on those lifters to make them eat another cam.

Valve job with new valve springs, cam, lifters, timing chain and gears are in your future.

Bob
tufcj

When the motor is turned over by hand the "stuck" valve never opens or closes, while all other do. What would cause this?

Also what would a machine shop normally charge to rebuild a set of heads?

82Waggy

Blown out lifter, damaged cam lobe, or bent pushrod. typical valve job only runs around 175 plus parts.