Cylinder head flow - What is crucial in a stocker?

[Paul Precht]

Originally Posted by Stan Weiss

Maybe someone who is doing stock heads will speak up. How far below the actual valve seat into the head can the bottom cuts / angles go? I have seen heads where those bottom cuts went well into the throat area. I don't know if those heads were NHRA legal or not.

Stan

Any machine cuts are legal and if that cut is 85 degrees or so it's going to go deep.

[Mark Yacavone]

Originally Posted by Paul Precht

Any machine cuts are legal and if that cut is 85 degrees or so it's going to go deep.

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[jamie2370]

Mark, that's what most all my heads have looked like till these 416 heads. They seem to have a deeper turn that didn't get touched

[Stan Weiss]

Originally Posted by Mark Yacavone

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Mark,
Thanks for the picture. It has been a while since I saw this head. But from what I can remember there was an area where the bottom cut went at least twice that amount below the seat.


Stan

[Doug Hoven]

Originally Posted by Bill Diehl

I don't know, you tell me.....according to the "experts" and there are many, the flow bench is worthless, I beg to differ, but what do I know?

I recently had the head off of the 6 cylinder on the flow bench. Boy were we surprised how good the head flowed even at the .388 lift I am allowed. Flowed better on the intake than a stock small block head, and the exhaust flowed 80% of what the intake did. The reason it flowed as good as it did was the fact that the intake ports(there are only 3 btw) are WAY too big. While I do believe flow is very important, when the rest of the engine (in this case the 200 cfm carb and small cam) can't support the flow you can get out of the head, you're going to run into an issue with air not moving fast enough. There's a reason the most common aftermarket chevy 6 cylinder head mod is to weld in a "lump" to the bottom of the intake port to take up some volume. As odd as a chevy 6 cylinder may be, I can only imagine the same principal applies to a wide range of combos.

[Henrys Toy]

Originally Posted by Doug Hoven

I recently had the head off of the 6 cylinder on the flow bench. Boy were we surprised how good the head flowed even at the .388 lift I am allowed. Flowed better on the intake than a stock small block head, and the exhaust flowed 80% of what the intake did. The reason it flowed as good as it did was the fact that the intake ports(there are only 3 btw) are WAY too big. While I do believe flow is very important, when the rest of the engine (in this case the 200 cfm carb and small cam) can't support the flow you can get out of the head, you're going to run into an issue with air not moving fast enough. There's a reason the most common aftermarket chevy 6 cylinder head mod is to weld in a "lump" to the bottom of the intake port to take up some volume. As odd as a chevy 6 cylinder may be, I can only imagine the same principal applies to a wide range of combos.

Good morning Doug and to all,
Back when all we had was stock castings from which ever car Mfg. that we chose to play with, was when the "advent" of commercial Flow Bench's came to be. The use of these machines has lead us to where we are today with all the aftermarket support, and the advertised Flow Numbers helped sell products. Now in todays world of Big Horsepower and Big Engines the cylinder heads that have been developed all started off life on someone's Flow Bench. Okay that being said - we as Stocker Racers should still be able to gather useful information from these Flow Bench's, especially given the Lifts that we have to deal with.
They may not be the Final answer, but I consider there use an asset in the further development of engine performance. It's a tool just like a dyno
so how you use the tools that are available to us will determine the amount of improvement you'll find in your engine development programs. The facts are right in front of you, follow them as you see fit.
Just my Two cents from a very small spot in a very large world.

Respectfully,
Henry Kunz 1534 H/SA