I just rebuilt my 388 again and upon firing it up there is a light knock, but definitely heavier than a tap. One thing i noticed is that my distributor seats but when it seats I can move the distributor forward and back. It seats all the way down against the manifold, but i can wiggle it. 50 lbs of oil pressure at idle, no smoke comin from the tail pipes, no bad vibrations or misses, but a knock. took the pan off, nothing obvious. I fired the engine up and took one plug wire off at a time and the knock continued. pushed in the clutch to make sure it wasn't the transmission and it still knocked. Oil level full. Any advice would be much appreciated. thanks, Grant...
knock knock
- Thread starter T56elcamino
- Start date
I was going to say to check for a cracked flywheel, but then I noticed that it's a 5-speed, not an automatic. Are you sure the flywheel bolts are tight? Does the noise correlate with RPM ? Does the knock get faster when you rev the motor ? Rocker arms hitting spring retainers ? Good luck, let us know, Lee
the knock does match engine speed. flywheel bolts are tight and have thread locker on them. I am running the same springs, cam, lifters, and all as I did before i pulled the motor, so i don't think thats what it is, i am just going to pull the motor back out and have a look see, but if anyone comes up with something please let me know, I think it may be something with the distributor, I tried a different distributor and it was also loose when it was fully seated. thanks again... Grant.
maybe check to see if all the valves are opening and closing the same, did anything fall down the carb into the cylinders?
yeah, i thought about that, I guess i'll take the heads off and have a peak, but then again it sounds like its coming from the crankcase, but If I can't find anything else, I guess I'll take the heads off...thanks
how about the endplay on your cam? possibly the quick sleave on your oilpump extension rod... if your distributor is loose, im thinking its either cam to gear or pump drive to dist related. good luck.
Does it sound like it's more on the driver side? Mine has a small noise like that heard more from the inside of the car though. More when it's cold and nearly gone when warmed up. :-k I guess this summer I will need to freshen it up and see just what shape the internals are in.
I had a knock knock in my 4.3 powered work truck i have been telling are so called motor head. And he took it to the chevy dealer and it was the crank they could move it more than 110 thousand,s back and forth and that motor ran great to redline. It would go away when it warmed up. Just a thought.
