346 Flathead engine knock

[Al]

Need some advice here guys....I've got a 41 with a 346 Flathead, supposedly rebuilt some 15K miles ago, but don't know the details.  I'm getting a knock, noticable at idle, goes away at idle when the engine is warmed up, but is always present, particularly under load.  The knock becomes a bit of a rattle when the engine feathers down from a rev at idle as well.  It is not horrible, but seems to be getting worse this season....I have had the car since the fall and never have noticed it before....

Pulling the plug wires sequentially, the knock goes away when removing the #1 plug wire.  The engine is probably a bit sludged and carboned as well, for whatever that is worth but this does not sound like a detonation knock.

I'm no expert on these engines, but I'm guessing that I've got a bad bearing or wrist pin, although who knows what might have lead to this condition.  Any other thoughts, or how I may try to rectify this without resorting to a complete teardown?  Can I simply drop the oil pan, remove the baffle and float, drivers side head and push the piston up through the block?  Do the bearings have any stamping to indicate their size in case the crank was ground?  Does anyone know any shops in Northern NJ that specialize in these engines?

Thanks much in advance.

[Dave T]

Al, it seems that you have isolated your knock to # 1 cylinder, your knock could be a rod brg. wrist pin, broken or cracked piston, or a noisy valve .By your description I would pull oil pan ( which is very easy) and check # 1 rod brg.move the rod side to side to see if there is any excess play. To remove bearing cap make sure you have the proper size and good quality socket ,as not to damage the rod bolts the bearing should be stamped on the back as to the size. you can also use a plastic gauge or micrometer to check the crank dia.If the bearing is bad and the crank is rough ,you will have pull the motor to remove the crank and have it turned. If the bearing looks good pull the cyl. head and push the piston out the top, I doubt that there would be a ridge to cut seeing that you stated that you motor was rebuilt 15000miles ago.
                                             
                                     Gool luck Dave T CL 22554

[al]

Thanks Dave, but don't I need to remove the baffle, oil float, and oil pump as well to do this?

[homeonprunehill]

AL Remove any thing that gets in your way ;. From what you hqave said about the knock going-away when it warms-up tell me that you have a"wrist-pen"going bad . Does it go away if you "jacik-up the idle rpm little"? Take your car to any NAPA store that has an engine rebuild in the same building, visit firstto see if the person that will be doing the work is either "bald OR going gray" Jim