Tappet too tight in bore?

Posted by JeromeSolberg On 2021/4/24 23:38:04
Hi folks,

The slow and much delayed process to re-assemble my '53 327 5-main/hydraulic lifter engine began in earnest today, after some delay caused by issues with new valve guides. I got those in and everything is fine there, and hand-lapped the new valves against the newly machined seats to make sure everything is fine there.

Now, I get the engine on it's side and start to insert the tappets back in their bores. I had the tappets lightly refaced by the local machine shop. Now I put them back in their bores and I find that, for about 12 of the 16 tappets, they don't go all the way down, some of them hit what feels like a "hard stop" just at the point they would emerge from the other side, whereas about 4 go all the way down. I tried different tappets in different bores and it seems an issue with the bores, not the tappets, because I switch tappets and the problem stays with the tappets not the bores. I am not sure how this could have happened, as these are the original tappets, and again it doesn't seem to be a problem with the tappets, it seems to be a problem with 12 (out of 16) tappet bores. For a few of the problem bores, it seems I could get the tappets to go in a little more if I apply some pressure while twisting, but eventually they just get stuck.

Any ideas? I have coated the tappets themselves with Redline Assembly Lube while I had been regularly coating the block with WD-40 to keep it from rusting. Maybe there is varnish in the tappet bores? Should I use something like Carburetor Cleaner on the bores?

Thanks in advance,

Jerome

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