Ordered a new set of tappets from LP Williams, 3 of them fit, 3 of them are too tight and bind in the holes. I can switch them around in different holes and it doesn't matter. I tried miking them and I couldn't come up with much of a difference in the diameters. What to do other than return them which will sit project back.
i had the same problem with some kibblewhite tappet blocks i put into my T120. thee tappets fit fine before i installed them, but the blocks compressed just enough afterwards for several of the tappets to fail to slip into the bores freely. i had my machinist ream the inside of the tappet blocks very slightly and they've been fine.
Polish the offending tappet stems with 1500 or 2000grade Emery strips cut to size, using the correct "belt pulling" technique and fit by trial, one by one. I have a stand mounted vice. I put the tappet foot in a soft jaw , then with a emery strip and a drop of light oil, walk around the vice slowly whilst simultaneously and continuously pulling back and forth on the strips. keep stopping and checking against the tappet block itself. Should work fine