Originally Posted by F-BIRD'88
disable one spark plug wire at a time while listening. This will ID a rod bearing and which cylinder.
Remove the valve coves and watch the rockers travel ( cam lobe)
Next time don't use a ZDDP additive. Use a oil that has the Zinc in it already. (many racing oils)
Sometimes it just plain dumb luck.
Nice that the builder is going to work with you, on it. Yup a good time to upgrade the cam.
A noise that disappears when the motor is warmed up is piston to wall clearance.
A noise that disappears when a cylinder is disabled and comes back when spark is restored is a rod bearing.
Can also be a exhaust system leak. And they can sound like a bearing.
Auto trans flex plate/ring gear crack is common. Exhaust leak is common.
Loose flywheel bolts. Cracked crank pulley. Mechanical fuel pump. Loose cam gear bolts.
Actually, the oil I used was Joe Gibbs should have the right amount of ZDDP in it. I knew not to use the additive
. I tried the pulling the spark plug wire on each cylinder one at a time with no change. Altough the knock almost goes away once its warm. The car doesnt smoke and the oil pressure is good. It knock also goes away if you run the rpms up just a bit. Its a solid knock, so I eliminated the exhaust. I checked the flexplate and bolts. 2 Questions Mechanical fuel pump I've heard that it could happen. How do you determine if its that causing it. If it is piston to wall clearance what could have caused it? Thanks