<VV> valve adjustment-- MY opinion

[Kenneth E Pepke]

This was common thinking when dealing with the later Chevy 283s ... in
some cases the engine oil pressure would be too high [10 PSI per 1000
RPM is enough] and it could 'pump up'  the lifters thus keeping the
valves
off the seats.  At high engine RPM this was not noticeable to the driver
but
when the engine was slowed to an idle sometimes the idle would be
rough until the lifters had 'leaked down.'  This condition can occur in
the
Corvair engine ... especially when the cylinder heads are hot but  the
oil is 
not yet up to operating temperature ... and it will limit the engine
output at
high RPM.  Yes, it can reduce the seat temperature relative to the head
temperature and it has long been believed that is why most seats [but not
all] fail after a relatively short time after starting the engine or
during a time
of heavy engine loading.  The damage is cumulative, that is to say over 
enough time the movement between the aluminum of the head and the 
steel of the seat loosens the seat. 

About three years ago my 1942 Chris Craft side valve 6 spit a valve seat
out the exhaust while I was crossing Lake St Clair.  Upon repair of that
engine it was found to have debris, built up over the years, blocking
water
flow to that area of the block.  

Four speed Corvairs, with that low ration St gear feel so good many have
a tendency to 'wind the engine out' and that can bring the oil pressure
up
quit a bit ,,, so more valve seats are dropped by those vehicles than
those
blessed with a PowerGlide transmission :-)  
Ken P

On Fri, 1 Aug 2008 23:08:46 -0600 Dennis PLEAU <ddpleau at msn.com> writes:
> One of my friends who is a well known Corvair mechanic once told me, 
> he tightened the valves on his cars and his performance customers at 
> 1/4 turn past zero lash.  Non performance customers got 1/2 turn as 
> they complain about the noise until the engine gets warm.  You pick 
> your driving style, you pick your prelload.
>  
> dp
> 
> 
> 
> > From: BobHelt at aol.com> Date: Sat, 2 Aug 2008 00:55:01 -0400> To: 
> N2VZD at aol.com; iscdirector at yahoo.com> CC: virtualvairs at corvair.org> 
> Subject: <VV> valve adjustment-- MY opinion> > What really is needed 
> it to accurately find the zero lash point and then to > tighten the 
> adjusting nut about 1/2 turn. This is not critical and can > 
> actually vary from just a slight tightening to a full turn as per 
> some of the shop > manuals. What should be avoided is bottoming the 
> internal piston which will > not allow correct valve operation and 
> will prevent the lifter from self > adjusting to the 
> expansion/contraction of the engine and valve train.> > Regards,> 
> Bob Helt> 
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