As an alternative to drilling the tappets, you might want to think about
honing the block passages that the tappets slide through to give more
clearance for the oil to drain.
When I bought my 79 B, I found that the cat converter must have overheated
the block to the point where the tappets were hanging up on the sides and
wearing the cam. I honed the passageways with a brake cylinder hone with
very good results. It certainly is more work than just pulling the tappets
out and drilling them, but I would be very concerned that the slightest burr
on the holes you drill could destroy the cam or pushrods.
I think that, if the clearances are so tight that oil isn't draining past
them, you may benefit from opening them up a bit anyhow.
Larry Daniels
----- Original Message -----
From "Glen Byrns" <grbyrns at ucdavis.edu>
To: <spridgets@autox.team.net>
Sent: Tuesday, October 26, 2004 10:11 AM
Subject: tappet oil drain holes
I'm pulling my new motor out to correct a problem that cropped up after only
a
few hundred miles. I've been haunted by excessive oil smoke and have
finally
traced the problem to pooling of oil over the head. On the recent rebuild I
went with a new set of chilled iron tappets that were not drilled with the
usual oil relief hole.
Vizard says these are fine and that plenty of oil will get past the tappents
to drain the head just fine.
I've not found this to be true. The snug fit of nice new tappets isn't
draining the head area fast enough to prevent pooling on the head. Oil
smoke
on start up, guides are new and double checked to close tolerance. New
rings
and pistons with just enough miles to seat them nicely and blowby is now
very
low. A peek into the filler cap after a long high speed run and quick
shutdown shows enough accumulation to stand above the stem seals. I know
the
1.5 roller rockers weep more oil than the original set, but I debuted this
set
on the old motor with drilled tappets and had no problem.
Has anyone else had problems with these undrilled lifters? My plan is to
pull
them out and drill the little suckers.
Glen "Blue Cloud" Byrns
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