Thanks Vance,
I thought you were recommending it, but didn't want to put words into
your mouth.
You know what they say... what's good for GM is good for the country...
:-)
Thanks,
Don
"Navarrette, Vance" wrote:
>
> Don:
>
> I *am* recommending the 30 degree back cut, the 3 angle valve
> job, a pocket port, and the necked down, polished valves.
> They all work. The only caveat is that each change by itself is
> very small, but added together they give real power. These are the
> small details that add up to real gains. The really nice thing about
> these is that they do not affect emissions or mileage, and they are
> increasingly used by the OEMs.
> My 1995 small block Chevy, for example had the 30 degree back cut on
> the valves from the factory. So GM believes in it too....
>
> Vance
>
> ------------------------------
> 1974 Mimosa Yellow Triumph TR6
> Cogito Ergo Zoom
> (I think, therefore I go fast)
>
>
> -----Original Message-----
> From: Don Malling [mailto:dmallin@attglobal.net]
> Sent: Monday, December 09, 2002 7:25 PM
> To: Timothy Holbrook
> Cc: 6pack@autox.team.net
> Subject: Re: Fwd: Re: Fwd: RE: 30 degree valve seats and 3 angle valve
> grid
>
> Hi Tim,
>
> Yes I ordered that back issue from Grassroots (Vizard) on a tip from Kai
> and Robert Lang -- I think. But I don't think it's the same idea. I
> thought the 30 degree angle they were talking about was on on the "face"
> on the valve -- the piston side, rather than the valve seat. Seems they
> were rounding the edge "face" to improve flow. The Vizard "A" series
> manual is talking about the valve seat angle. The fact that he doesn't
> mention the 30 degree valve angle in the DIY head porting article maybe
> means it's not all that important -- but I thought Vance recommended
> it... Maybe not, or maybe not strongly...
>
> >From Vance...
>
> However, when you add a 3 angle valve job to a 30 degree
> back cut on the valve, necked down stems, polished valve faces,
> and a mild pocket port, you can achieve improvements on the order
> of 10% more HP, with no impact on emissions or drivability.
>
> FWIW, Kas's manual shows the same sort of rounding on the valve face as
> does the Grassroots article.
>
> Don
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