[AFM744]

Originally Posted by DonE

4 of 6 heads had trashed guides, both intake and exhaust. The valve stems were trashed as well but they sealed just fine on their seats - compression and leakdown tests were all good. The only explanation given was bad guide material.

Don, do you know which guides your previous machinist installed? Also, which stem seals did you use? Obviously these guides should be blacklisted.
I thought my exhaust guides were bad, with about 1mm clearance at 89k mi. Then at German Precision I saw some reeeeally worn guides, like you could put an extra valve or two in there!