The problem I have seen with the integral valve seat on the exhausts is pitting
of
the seat. I have been told that what is actually happening is that due to the
heat, particles of the cast seat are welding onto the valve leaving the surface
of the seat pitted. The hard seats eliminate this problem.
Richard Good
Greg Dito wrote:
> Stuart,
>
> I've been told the same thing about hardened seats. The idea is to improve
> heat transfer from the red hot exhaust valve to the head which acts as a
> heat sink. The hardened seat serves that purpose. Intake valves run much
> cooler and so hardened seats are not really necessary. As far as the
> argument about unleaded gas I ran my 250 as a daily driver for four years
> (about 60,000 miles) on Amoco unleaded premium almost exclusively with no
> issues.
>
> Greg Dito
> CD6250L
>
> ----- Original Message -----
> From: "Richard Good" <goodparts@desupernet.net>
> To: <StuBeatty@aol.com>; <6pack@autox.team.net>
> Sent: Monday, October 20, 2003 11:16 PM
> Subject: Re: New Valves
>
> > Stuart,
> >
> .... I recommend Stellite exhaust valves with hard seats and the stock
> intake valves. I
> > don't think hard seats are necessary on the intakes.
> >
> > Richard Good
> > Good Parts
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