<VV> Performance Valve job

[Bill Hubbell]

I'm sure it's not that simple.  You'd still need to cool the heads from the 
heat released by that "cheap horsepower"

Bill Hubbell


----- Original Message ----- 
From: "Scott Cable" <s2cable1 at yahoo.com>
To: <virtualvairs at corvair.org>
Sent: Wednesday, June 15, 2005 1:59 PM
Subject: <VV> Performance Valve job


> Vairheads,
> I've been working at night at the local engine shop that is equipped with 
> a Pro-Flow 600 flow bench, and a Superflow dynometer.  I was testing a 
> unmodified World Products SBC head and compared that last night to a 
> barely legal World Products head.  The differences between these heads 
> were that the barely legal head has a 5 angle valve job vs the customary 3 
> angle.  The valves also were back-cut with a 30 degree angle also.
>  The differences in flow were astonishing.  The modified head flowed over 
> 10 percent more than the unmodified head. (275 CFM vs 260 cfm best flow 
> either head) Even more impressive was the flow numbers at the smaller 
> valve lift openings.  The modified head just would not quit.
> How this equates to horsepower is:HP=CFM * .2527 * # CYL
> Theoreticly the mdoified head would be able to produce 556 HP vs 526HP of 
> the unmodified head.
>  So those of you who are going to be doing a valve job, you may want to 
> pay the extra expense of back-cutting the valves, and adding a 15 degree, 
> and 75 degree cut, concentric on the valve guide in the head.  Obviously 
> you need to take your heads to a reputable shop to perform this work. The 
> new seat angles are produced with a cutter, NOT a stone.
> Cheap horsepower.
>
>
> Scott Cable
> Jamestown, ND
> s2cable1 at yahoo.com
>
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