do burnt valves cause low compression?
I’ve got some valve noise in a 400 pontiac motor, thought maybe burnt valve, but compresssion is within 2 pounds of each other.
Yes, but burnt valves are not likely the cause of this valve noise and burnt valves on a Pontiac 400 would probably be an anomaly.
So, what are the compression readings?
If your valves are sticking closed ,that won’t hurt compression until they burn badly enough to erode the valve or seat.
You have no burned valves. You have stuck or worn out valve lifters. I don’t think Pontiac rockers were adjustable, so first, try a can of something that claims it can “Free stuck lifters”…
compression on all eight are about 120 pounds, warm WOT good charge.
i thought burnt valve b/c i had an exhaust leak for a while.
the motor make a ticking around 1,000 rpm seems to have lost some power.
probably only 10k miles on motor.
car’s a 73.
120 psi on a Domestic V-8, not good, at least they are even.
Agreed. A 120 PSI pretty much sucks and you need to go back and run a wet compression test.
If the results increase after a small squirt of oil then the engine builder has made at least 8 errors.
Throw in a ticking lifter and the number of errors could become larger than 8.