[alfa] Re: alfa-digest V9 #1082 - Valve shims

[AlfaNeely@xxxxxxx]

In a message dated 1/14/2004 11:47:40 PM Central Standard Time, 
owner-alfa-digest@domain.elided writes:
Date: Wed, 14 Jan 2004 21:00:29 -0700
From: C M Smith <cmsmith@domain.elided>
Subject: [alfa] Valve shims

Don't these have to be of hardened steel to resist the pressure of the 
hardened cam faces? If so, then sanding them will take forever and be 
counterproductive in that the subsequent wear will increase the clearances 
pretty rapidly.


Michael Smith
White 1991 164L
Original owner
----------------

    I have used a surface grinder to grind valve shims for years.  I have a 
friend with a very nice machine shop including the surface grinder.  It is so 
accurate you can grind shims to less than half of 0.001 inches.  That is more 
accurate than you can get with a feeler gauge.
    In all that time, I have had only one valve shim die.  That was on my 84 
Spider SCCA race car that regulaly sees 7,000 + RPM.  When I tore the engine 
down, the valve shim was gone, leaving only powder and a lot of damage to the 
top of the valve spring retainer, keepers and the inside of the cam follower.  
I had to weld a bolt to pull the cam follower.  I had to replace the valve, 
the springs, the follower and clean up the bore for the cam follower.
    So it could be that the valve shim cracked - possibly for reasons Mr. 
Smith states above.  Or more likely, the valve could have floated, allowing the 
shim to move out of alignment and get hammered.  The valve springs had not been 
replaced for some time prior to that incident, but are now new.

Ciao,
Russ Neely
Oklahoma City
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