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High performance valve job
Posted by: polymer ()
Date: August 14, 2007 10:41AM

I've heard that grinding the seats to seal on the outer edge of the valve flows more than one seated in the center of the valve. Does anyone have any experience with this?
Would this shorten the life of the valve?
What angles are a 3 angle job ground at?

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Re: High performance valve job
Posted by: MattNall ()
Date: August 14, 2007 10:52AM

That is true...but it causes the valve lip to overheat in short order......only used in drags... IIRC

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High performance valve job
Posted by: Steve O ()
Date: August 14, 2007 10:53AM

This Acura Forum article is a good one to review, with lots of links to other articles also: [www.team-integra.net]

It shows how a 30/45/60 degree seat grind is done.

Also, review Mark Langford's 3100cc Corvair engine valve job project details at [home.hiwaay.net]

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Re: High performance valve job
Posted by: polymer ()
Date: August 14, 2007 12:13PM

Langford mentioned not using valve stem seals and I've heard this from another source.
Has anyone here left the seals out?
Does it use oil without them?

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Re: High performance valve job
Posted by: MattNall ()
Date: August 14, 2007 12:18PM

The valves are horizontal... not angled towards verticle....so if guides are not worn...little need...

Most use them on intakes though...

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Re: High performance valve job
Posted by: Brizo ()
Date: August 14, 2007 06:51PM

Valve seals on a Corvair will increase oil mileage and keep the back of the intake valves cleaner maintaining better air flow. The vacuum is constantly trying to suck oil down the guides. I've torn down low milage rebuilt Corvairs that had the intake ports nearly coked shut because they had no seals.

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Re: High performance valve job
Posted by: Spectre ()
Date: August 14, 2007 07:33PM

Never put the seals on the exhaust valves. THe factory did put them on the intakes, but not the exhaust.

David Clamp


1965 Corsa convertible - 140 4spd/3.55/AM-FM

2013 Mustang GT convertible - 5.0, 6spd auto, Procharger i-1

2003 Miata SE - 6spd manual (wife's toy)

"Victory is mine!" - SG

Oklahoma City, OK

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Re: High performance valve job
Posted by: polymer ()
Date: August 15, 2007 03:55AM

Steve O Wrote:
-------------------------------------------------------
> This Acura Forum article is a good one to review,
> with lots of links to other articles also:
>
> It shows how a 30/45/60 degree seat grind is
> done.
>
> Also, review Mark Langford's 3100cc Corvair engine
> valve job project details at


Thats some pretty good stuff. Thanks Steve.

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Re: High performance valve job
Posted by: Scott V ()
Date: August 15, 2007 04:23AM

polymer Wrote:
-------------------------------------------------------
> I've heard that grinding the seats to seal on the
> outer edge of the valve flows more than one seated
> in the center of the valve. Does anyone have any
> experience with this?
> Would this shorten the life of the valve?
> What angles are a 3 angle job ground at?

From what I have been told and seen you can get good gains in flow by makeing sure the intake valve gets all the seat margin you can out of the seat size.

Important also is the angle of the valve and the top angle on the seat. About two years ago I spent an evening with Ray Sedman of american-pi and he showed me some very neat stuff on the flow bench. On a test head he did a stand 3 angle valve job just like most people use. Then he put a small angle on the top of the seat and the flow pick up some. Than another angle on the bottom of the seat and more flow as gained. After that he took the valve and did some other grinding to the valve and the flow got even better at the smaller valve lifts. Just to make the point he said he would change the angle on the top of the seat by two degrees. Tested the head again and it was almost back to the regular three angle valve job.

He told me that 140 heads need different angles than the other smaller valve heads. Turbos use another angle to get the best flow. But it shows you that a of of testing is done to get the best results. What works well on one engine, like a honda may not work on a Vair.

I did not see any of his work on the exhast valve, so I dont know much about that. But I am pretty sure you need different angles for the intake and exhaust to work the best.

-Scott V



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Re: High performance valve job (old topic)
Posted by: toytron ()
Date: May 17, 2017 06:54AM

Hey Scott or Ray,

Would Ray like to share his findings? ggg

Thanks,

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