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Re: Smoking at the light

To: James Franks <jimmble@adelphia.net>
Subject: Re: Smoking at the light
From: "Robert M. Lang" <lang@isis.mit.edu>
Date: Mon, 4 Apr 2005 09:36:11 -0400 (EDT)
On Mon, 4 Apr 2005, James Franks wrote:

> If the compression is good, freshen the head. It may just be worn valve
> guides or valve stems. Mic the stems to see if they are worn, and have your
> machine shop put seals on the intake guides. Use iron guides.

All the above is good advice. However, I need to caution on the last
statement - use iron guides. The stock guides are iron, but the
replacement guides that are out there seem to be of dubious quality. You
need to make sure that the guides have the proper holes drilled in them.

To make a car 100% stock (for SCCA street prepared autocross), I needed
new valve guides. The rules say STOCK guides. I bought a set from one of
the big three, but when we ran a bore gauge trough the guides, we found
the bores to be stock dimension on the ends but  to .003" LARGER in the
middle.

This would have resulted in a motor that would run okay at first, but
would likely start smoking after not-too-many miles.

The "cure" was that we bought another set or two of "spares" and then
picked the best of the lot.

I still have a pile of new valve guides from that exercise, although to be
fair to the vendors, some of the guides that were slightly out of spec
have been used in other applications.
 
> Jim

regards,
rml
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