[turbo69bird]

Anyone know the specifics of the Eliptical valve job they spoke of in their books? I’ve heard others discuss this but haven’t heard the specifics of it.

[steve25]

I have both of McCarthys books and there is not word one in there about any such valve job.

All there is shown in one book is a as of that time period legal NHRA valve job for the stock class of cars.

Can you give a specific book title and page numbers?

In terms of running a boosted motor like you are, I don't think the issue of reversion is as great.

[sdbob]

I have their books and previous H-O racing newsletters about their cars and H-Os cars and books and nothing mentioned about elliptical valve design.

[Stan Weiss]

The only thing I have seen, is a non round throat area and it was not in a Pontiac head.

Stan

[PAUL K]

I don't recall Pete getting much into the details of his elliptical valve job. In fact he was pretty much tight lipped on the details of his Super Stock valve job he shared the flow numbers in his second book... Probably with good reason.

These pictures are of an elliptical valve job done back in the 80's by one of the top Pontiac head porters. The top cut mimics the bottom cut just not as pronounced due to the small top angle.

[steve25]

That looks like a original Production RA4 casting you got there.

It’s so obvious that those chambers where a refinement of the 1967 061 head.

[turbo69bird]

Originally Posted by PAUL K

I don't recall Pete getting much into the details of his elliptical valve job. In fact he was pretty much tight lipped on the details of his Super Stock valve job he shared the flow numbers in his second book... Probably with good reason.

These pictures are of an elliptical valve job done back in the 80's by one of the top Pontiac head porters. The top cut mimics the bottom cut just not as pronounced due to the small top angle.

Thank you for the info, I know it was printed somewhere but very little info on it. I had talked to him about it once but it was very long ago maybe late 90s. Figured someone had to have some info on it. David visard has mentioned it before also he also mentions a mod he used for reversion on his mini copper that gave him a much wider power band .

This isn’t for one of my turbo cars they dont care much about head work it’s for a NA set up. . Which sadly I’m just not that well versed in anymore after turbocharging for so many years
I used to race NA w quadrajets and I can hardly remember anything from back then. I do boats , 2 stroke outboards, airplanes lycoming mostly, 2 stroke yamaha jetskis supercharged 4 stroke seadoos, , dodge deisels , it all gets confusing after a while . Too many directions
Either that or I’m just plain getting old .

[turbo69bird]

Had me thinking it wasn’t in there haven’t read these in many years . Was just about my Bible at one time.

[steve25]

Ok so he does mention it, but gives no details.

The main benefit I see with that type of valve job is to enhance the effect of port bias that is inherent in any non Hemi type head ( non wedge chambers ) with parallel valves .

In a way Vizard has done the same thing with his patented 4 valve Hemi mod where one intake and one exh valve are a little smaller then the other two.

If you have a flow bench and the equipment to do valve jobs then the bottom cut depth/ height around the bowl is what will have the most effect on minimizing the velocity profile differential between the long side of the port and the short side, be it intake or exh.

Like you said, when running boost this matters very little, unless your cam pick is way over the top!

[sdbob]

Uh oh i need reread his book.

[Stan Weiss]

Originally Posted by turbo69bird

Had me thinking it wasn’t in there haven’t read these in many years . Was just about my Bible at one time.

Thanks for posting those since I don't have Pete's book. After reading those pages here is what I take away from them.

Stan

PS - Some might find this thread interesting.

Dykem and a Flow Bench
https://www.speed-talk.com/forum/vie...7f0bfc4a52d48f

[turbo69bird]

Take a
Look at 6.58 in this video

https://www.youtube.com/watch?v=Bw8AimHAlII

[turbo69bird]

and I know some of you have seen this already but thought it was relevant to add to this thread as well


https://youtu.be/mQwon4Gfzfo