Re: Engine knock
Have you checked the valve adjustment? Excessive valve lash on one valve/rocker arm will make enough noise to make an untrained ear think something more major is going on. Putting pressure on each rocker arm as the engine is tapping may change the sound on the loose one.
Before pulling the pan again, with the engine tapping, remove one spark plug wire at a time, see if taking a cylinder off line will change the sound at all. If it does, then go looking at that particular cylinder for a more serious problem (bearing, piston/pin).
Another possibility is a weak fuel pump spring, allowing the fuel pump arm to lift off the cam and slam back onto it making a loud lifter/valve adjustment type noise. Remove the pump and start the engine (it will run for a short time on the fuel in the carburetor bowl).
|