Great Bend Stock DQ

[Bob]

Originally Posted by SSDiv6

I know for a fact that NHRA does not have all the cylinder head volume specs from virgin heads. As a matter of fact, many of the volumes in the SS list are from cylinder heads that were already ported when they did not even have a spec available for a stock virgin head and when it was still illegal to port heads in SS. By the way, at one time, I used to be an SFI NHRA Tech. Terry Bell who goes under the X-Tech-Man in this forum also knows about this issue and has made very valid points on this issue before.

I would agree that they do not have them all, but they have the popular ones. And I would agree that some were drawn on, at that time, bogus heads.

So, by your own admission, SS spec's (for the most part) are to big to use for a stock head---Correct?

So when a 283 head pours 10% more than the SS spec, how do you defend that? How can you justify that big of a runner? Surely, you don't expect me to buy into the new valve rule as being the cause?

[SSDiv6]

Originally Posted by Bob

I would agree that they do not have them all, but they have the popular ones. And I would agree that some were drawn on, at that time, bogus heads.

So, by your own admission, SS spec's (for the most part) are to big to use for a stock head---Correct?
Some are, others are not. Some heads that have big numbers, will slow down the car in a Stock application; on others will pick up, and on others, there will be be any change. I know of some of the shown SS spec volume numbers that are actual OEM stock numbers that will not have any effect in a Stock application. There are also more variables that would dictate performance such as engine size, type of induction, manifold style and cam lift.

So when a 283 head pours 10% more than the SS spec, how do you defend that? How can you justify that big of a runner? Surely, you don't expect me to buy into the new valve rule as being the cause?
I will not speculate on this particular case since I was not there and I do not know the whole story. Nevertheless, if the port was 10% larger than the SS spec, I would agree it was more than valves and plain stupidity.

[Bob Sherwood]

I don't think this is that complicated. NHRA is pouring stocker heads to get data for future specs and what they are saying is , if you pour bigger than a SS spec your out. end of story ! I think a clarifcation by NHRA , as to what they are doing , would put this confusion to rest.

[William Koski]

They poured the runners on my head (cylinder) at Gainesville 5 or 6 years ago. As far as I know there were only 2 of us running that head at the time?

[Bernie Cunningham]

Word has it that the stocker volumes are very close to been done ( upwards of 90+%) and that we'll see 'em published around Indy time. Everybody, just hold ya breath until then! LOL
The way I figure it, those numbers will give us some 'lines to paint between'. However, I'm still concerned about the runner surface texture that can be positively identified as a stock surface. Should it match the texture of another outside surface, i.e. inside the head under the valve cover , around the valve springs?????
There's plenty of recent technology that can measure the texture and it wouldn't be that difficult for NHRA to step up to the plate and purchase such instruments i.e. a profilometer. An industy standard method of checking for welds and acid has been around for sometime now, it really is not that hard to detect!

Disclaimer: I'm a bit of a dinosuar racer, meaning my heads are completely untouched, give me some specs and checking methods and that'll probably change!

[SSDiv6]

Originally Posted by Bernie Cunningham

Word has it that the stocker volumes are very close to been done ( upwards of 90+%) and that we'll see 'em published around Indy time. Everybody, just hold ya breath until then! LOL
The way I figure it, those numbers will give us some 'lines to paint between'. However, I'm still concerned about the runner surface texture that can be positively identified as a stock surface. Should it match the texture of another outside surface, i.e. inside the head under the valve cover , around the valve springs?????
There's plenty of recent technology that can measure the texture and it wouldn't be that difficult for NHRA to step up to the plate and purchase such instruments i.e. a profilometer. An industy standard method of checking for welds and acid has been around for sometime now, it really is not that hard to detect!

Disclaimer: I'm a bit of a dinosuar racer, meaning my heads are completely untouched, give me some specs and checking methods and that'll probably change!

Bernie, the problem is that surface texture is subjective, especially when the OEM used various foundries. Also, the condition of the tooling and molds has a lot to do with surface texture and also with core shift. With the exception of aluminum heads, you will see always a variation of surface texture in cast iron heads. I have seen this with many different makes of cast iron cylinder heads.

So, if NHRA starts to use a profilometer, who is going to establish the values and surface finish criteria? The surface finish criteria is different for all OEM's. Who is going to send the NHRA staff to train in metrology? The fact is that you do not need to have a smooth surface to make power with a low lift application. The new valve rule is what you will see as the one of the items improving performance in the class. About acid, there are numerous ways to neutralize and remove all traces of acid from cast iron and aluminum making it undetectable.

I am more worried of metal spraying than acid; hogging out a port is not the only key of making power: the shape of the port and runner is the key for velocity and to power. ...and no, you are not a Dinosaur racer; you have many valid points. The problem is that NHRA cannot keep up with either the technology that is available and the creativity of racers.

[Bill Grubbs]

Not speaking for Bernie, but I believe he was inferring that if the runner texture does not match the other "cast" textures on the same head there "may" be a problem. For instance, in a 441 SBC head if the textures of the runners is not the same as the texture on of the cast surface under the valve cover, or the exterior of the runner on the underside of the head, then there "may" be a problem. Therefore if you were to do some runner "work" you would have to re-work all the cast surfaces on the head (time and $$$).

Bill