I rebuilt a 351M engine, new edelbrock cam, new bearing throughout, stock pistons, 4bbl intake manifold. High volume oil pump is showing 65 lbs. oil pressure at idle, and idles nicely. The cam I am using has .510 lift intake, .480 something exhaust. I am having a problem with the intake lifter on #4 cylinder tapping. I put a new set of lifters in the engine, and still the same lifter is tapping. I have no rocker wear, and the pushrods are not bent or wrong, as I put the same valve train parts back in the engine. There is no coil bind on the springs, and a valve job was done. The only thing I can think of now is there may be trash in the oil galley that feeds the lifters, and it is interupting oil flow and pressure to that one lifter. Any help from anyone would be appreciated. I also tried changing the oil to 20w50 and put marvel mystery oil in it...no help.

 

I'm assuming it the later engine that you don't have to adjust valves on if so check that rocker at the pivot that is where they usually wear new pivot post should come with new rocker if i remember correctly