[Shotimes] Re: Valve clearances

[Grant Butler]

Here's the specs for the valves if anyone needs them ...


----- Original Message ----- 
From: "Donald Mallinson" <dmall@mwonline.net>
To: <TechSHO@topica.com>
Sent: Sunday, March 21, 2004 10:26 AM
Subject: Re: Valve clearances


> Almost never does the valve recess causing tight clearances.
>
> The most common adjustment is to the exhaust valves.  Most
> SHO's at about 150,000 miles need 3 or 4 exhaust valves
> brought back into range.
>
> Shim thickness varies depending on original valve length,
> valve seat tolerances and cam lobe variation.  Usually most
> clearances are just .001 or .002 out of "range" but to bring
> them back into perfect center adjustment may take .004 or
> .005 shim thickenss increase.
>
> Much higher wear would be a factor of possible failure of
> the hardening of the shim, cam lobe or valve stem or all
> three would be my guess.
>
> I rarely hear of SHO's with valve clearances that go all out
> of whack.
>
> Don Mallinson
> SHO Club
>
> Mike Thompson wrote:
>
> > For those who have found abnormal shim clearances when doing the 60K,
> > which direction have said clearances gone? IOW, what starts to wear the
> > most first?  Do the valves recess into the seats and reduce clearances,
> > thus requiring smaller shims, or does something else happen?  Why would
> > someone's clearances radically increase, requiring shims in the ~2700
> > range?  Not raced or even driven particularly hard.
> > Mike
> >
> >
>
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