<VV> Valve Seat Fit - VERY rough calculations

[Roger Gault]

I don't know what the alloy used in the heads is, but it's probably got a
compressive yield strength of somewhere around 25-30 ksi.  At 450F, it's
probably about half  to 2/3 of that.  If you run one of the interference fit
calculators that you can find on the web, you'll find that for a seat
diameter of 1.75 (guess for a 140 intake), 15-20 ksi will only support about
.004" of interference before the head material begins to yield.  So, heat it
up good one time and that's all the press you have.  Lose concentration at
the same time you lose a belt and run it up to 550 or so and.......

Of course, at operating temperature the head expands faster than the seat,
and about .003" of that press goes away.  I wonder why we have a problem?
;-)  Maybe we should try BeCu.

Roger


----- Original Message ----- 
From: <BobHelt at aol.com>
To: <vairologist at verizon.net>; <virtualvairs at corvair.org>
Sent: Thursday, May 03, 2007 11:22 AM
Subject: Re: <VV> Valve Seat Fit


>
> In a message dated 5/3/2007 8:10:02 AM US Mountain Standard Time,
> vairologist at verizon.net writes:
>
> So if  you have a seat fitted at .005 and another fitted at .010, within
very
> few  heat cycles they will both be exerting the same shrink force on the
> seat.  I don't know of anyone who has pulled a perfectly good fitting
seat out
> to measure the seat bore after a hundred cycles just to measure it so
this
> will just have to remain my opinion.
>
>
>
> Smitty,
> That is NOT just your opinion. It was stated by an authority too.  <ggg>
>
> Bob Benzinger said that same thing  in one of his speeches. Not  in as
> specific terms as yours, but with the same meaning.
> Regards,
> Bob Helt
>
>
>
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