Re: Worn Rocker Arm & bore

Posted by Bob E. On 2018/9/7 12:16:00

thanks Jack.

I replaced all the lifters and all of the old ones show the circular wear pattern implying that they were rotating before this rebuild.

The cam wasn't reground for this rebuild (machine shop recommendation) so I would think that if the lifters were rotating before and not now that it wouldn't be the cam lobe taper. (unless I just ruined the taper in my initial startup because the lifters weren't turning for some other reason. the non-turning lifters still have some convexity to their face)

I don't know what the machine shop did to clean out the block and bores. They seem smooth and I have cleaned them really well now with a plastic bore brush, soft cloth, and brake cleaner. When I put this together after the rebuild, I was liberal with the assembly lube between the cam lobes and the lifters so I am sure that some of the moly-based lube got into the bores too. There was a little 'grittiness' in the bores when I took out the lifters but some of that was probably when i took the tappet valley cover off and stuff dropped in.

This time I was going to be more obsessive with cleanliness, not get any lube in the bores or on the sides of the lifters and just use oil for that part: Reserving the cam lube for the lobes, dist gear, and maybe lifter seat and rocker arm socket.

0.25" seems like plenty. my heads were not milled (nor was the block faces) after the machine shops checked them. The rocker arms tips were very lightly reground. Head machine shop ground the valve stems to be the same installed height. He really wants me to check lifter pre-load to make sure that there is not too much causing this or affecting valve open/close time.