yellow rose
Overnight Sensation
It would take one weird flow bench set up to flow a flat head block.
I made up some stuff to test flatheads with my flow bench. Waste of time.
It would take one weird flow bench set up to flow a flat head block.
Yea, but it is easy to visualize the air flowing into the combustion chamber having to bounce off that close vertical combustion chamber wall and causing a restriction. At the same pressure more air will flow through a 2 inch hole than through a 1/2 inch hole.
And I have seen flow improvements on my flow bench when the valve shrouding was relieved.
Two more things, 1) when working to improve port flow, there is almost no place easier to work and with less risk than the combustion chamber wall next to the valve, just leave room for the head gasket seal.
2) one of the critical set up characteristics when doing flow bench work is duplicating the cylinder diameter of the block that the head being tested will run on. Blow the cylinder diameter out larger and flow values go up. That is evidence that valve shrouding has an effect.
I said it earlier but if you make the area around the valve bigger just because it flows more you are killing power. Just because the flow bench says more air flow doesn’t make it better.
In some cases.I said it earlier but if you make the area around the valve bigger just because it flows more you are killing power. Just because the flow bench says more air flow doesn’t make it better.
I wouldn't say so. I've dealt with hundreds if not thousands of different cylinder heads and I've never seen a combustion chamber where the intake valve is down into a pocket like that. After some research ford only used this head for one year. It was that big of a failure. Factory rating on this head is down 25hp previous year and next year.Typical of a factory closed chamber head.
In some cases.
Flow benches are just tools. They try to replicate a characteristic of a running motor...but don't accurately simulate a running motor.
Just a thought i have is when you negatively alter the fuel distribution around the valve, or have a biased port... that burn time and efficiency takes a hit.
But be more specific. Is it chamber to bore or chamber to valve. Tossing statements like "just because it flows more air doesn't mean it makes more power" Who should toss their heads in the trash and why..?
And lets talk about flow setup on the bench and the effect of bore center and placement of the shrouded side of the bore lining up. Throw in the importance of an intake manifold straight wall lining up perfect with the port straight wall on power and the reflected flow increase on both the bench and the dyno, volume, discharge etc..
In what example are you using to it's relevancy?
Dissect it more and explain what you are trying to say to these people.
Ill have to re read your post. I interpreted it as you were aiming at the chamber shape itself being intrusive. You can buy lots of aftermarket iron heads, well...I wouldn't say lots but I quite a few.. where the valves are literally sunk a bit. Many people get their heads reconditioned by old-timer shops that do it...or after many valve jobs the valves are also very sunk. There is more to a good valve job than just the seat.I wouldn't say so. I've dealt with hundreds if not thousands of different cylinder heads and I've never seen a combustion chamber where the intake valve is down into a pocket like that. After some research ford only used this head for one year. It was that big of a failure. Factory rating on this head is down 25hp previous year and next year.
Yes, I agree with you. But I cannot see how this design would ever be a good idea. Even if they were directing the intake charge to get more 'swirl', it could have been acomplished just with the shape of the chamber like with so many other heads.My comments are Simple. I think people see things other people talk about and latch onto ONE thing and cherry pick it. It's my opinion that "valve shrouding", while certainly can have an effect, is not a combo killing point, right by itself. That's the point I was trying to make.
Yes, I agree with you. But I cannot see how this design would ever be a good idea. Even if they were directing the intake charge to get more 'swirl', it could have been acomplished just with the shape of the chamber like with so many other heads.
Yes, I agree with you. But I cannot see how this design would ever be a good idea. Even if they were directing the intake charge to get more 'swirl', it could have been acomplished just with the shape of the chamber like with so many other heads.
Because it was. It came when the manufacturers were forced to do something for emissions as per the EPA. Performance was the last thing they were thinking about. They needed efficient combustion. Hell, Ma Mopar started using computers (Lean Burn system) and roller cams in production. They had a lock-up converter transmission with more innovations to come.Yes, I agree with you. But I cannot see how this design would ever be a good idea. Even if they were directing the intake charge to get more 'swirl', it could have been acomplished just with the shape of the chamber like with so many other heads.
Look at my 66 273 heads. Look familiar?Larry Shepard has written in many publications about them finding swirl properties in heads like all of the letter castings, such as X, O, U, J and so on. They were swirl heads before Chrysler even knew about it. It was a complete accident. I've always felt that was one reason why the small block heads were generally better than all the other manufacturers heads of the same era. Even being a smog open chamber, they got the job done.
A little more shallow and no eyebrow between the valves. 920's are the same. I have a nice pair of those as well.That's a better chamber than the 302, in my opinion.
I have to ask how thick those factory steel shim gaskets are?A little more shallow and no eyebrow between the valves. 920's are the same. I have a nice pair of those as well.
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Let me look it up.I have to ask how thick those factory steel shim gaskets are?
That's a tough one to answer. .030 - .022 The .030 was the fire ring and the .022 was the very outside corners near the outboard head bolt holeI have to ask how thick those factory steel shim gaskets are?
"Swirl port" is bullshit marketing.
Many years went by before it dawned on me..
The 360 intake port shape, whether on the small side or not...didn't change from the intro of the j head to the "swirl port 308" . Its picking an event and marketing it cause it sounds cool.
Yes, I agree with you. But I cannot see how this design would ever be a good idea. Even if they were directing the intake charge to get more 'swirl', it could have been acomplished just with the shape of the chamber like with so many other heads.