On Fri, 17 Aug 2007 08:14:50 -0500, "Jim Burns"
wrote:

I "think" the problem was when Lycoming switched from alum/bronze pin caps
to aluminum caps. I've been told there is no problem with either the
alum/bronze caps that preceded or followed the aluminum caps, nor is there a
problem with the aluminum "piloted" press fit ends that are pressed into the
pins. Superior also makes pins with press fit plugs, although they problems
with the pins cracking in an earlier version.

Superiors SL points out that you can not mix pins/plugs of different weights
on the same engine.

Can an A&P familiar with the different pins chime in?

Jim

Pretty much nailed it. Minor nits, the piloted pins don't "press" in,
they slip in quite nicely until the inside of the pin gets varnished
up.

Every once in awhile they just start shaving. Have seen issues with
ALL the types in service.

Lycoming useta say "unofficially" that you could mix plug types if you
paired them in opposing cylinders.

Am curious what the OP or his tech found that requires cylinder
replacement.

Regards;

TC