Re: Question about tappets....

Posted by Owen_Dyneto On 2012/2/1 17:38:41

You can replace lifters individually, but honestly if several have "given up the ghost", why take a chance on leaving others of the same vintage in place.

Though I'm sure many have had good experiences, it's generaly not a good practice to put new lifters onto a camshaft that may be worn. Best practice is to have the cam removed and polished or profiled before putting new lifters in.

Hardened valve seats (exhaust only) are hardened steel rings complete with the valve seating face. A special cutter is installed in the guide (after a new guide has been installed, preferrably) and the block cut to sufficient relief to allow the new hardened seat to be installed. Usually a shrink fit - chill the guide first and when it expands to room temperature it is a permanent fit. Others will comment on the requirement for installing these seats but it would be recommended for an engine that going to see hard, continuous high speed service and not required to engines that see a more liesurely life. The tetraethyl lead that was once in gasoline acted to lubricate and protect the exhaust valve seat, thus the requirement for hardened seats or induction-hardened conventional seats is an advent of the no-lead era.

Easy to install lifters but I'll let others who have done it more recently that I comment.