When the engine is idling I have a slight knock. I pulled each spark plug wire but the knock does not go away. Should I just live with this or is there something short of dropping the pan that I can do to trouble shoot it. The truck runs good so I don't think its anything to do with the timing.

Mike Q

Sounds like a main bearing knock. You can pull the pan and check it out, and possibly remove some shims to correct the problem.

Will do, Can you advise what should be the gap for this, I already bought a new pan gasket and guess its time to open her up.

I had the same problem on my '27 (it also needed additional engine work on pistons and valves, so it was entirely rebuilt). On close inspection, the middle bearing was out of round, which I understand is caused in part by the lubrication system. We turned the crankshaft and re-babbitted the bearings, but that gets into major engine work with accompanying cost. A good place to start is with the shims, as suggested by JD.

Corona47, if you don't mind saying would you tell me who did the re-babbitt work for you?

Would you have them do work for you again?

Thanks

It could also be excessive piston clearance. We have had several early 6 bangers with 0.005" < clearance > 0.015" that clunked at low speeds. Also if the thrust on the crankshaft is greater than 0.010" you can get a clunk. The thrust is controlled by the sides of the center main bearing. So if you don't find the center main to crank out of spec then check further.