Re: Great Bend Stock DQ
 

Did I ever say NHRA used the SS spec, NO. Please re-read my post if you think I did because I did not.
My post was a statement of my opinion. Here is one more opinion---Maybe they just used common sense?

SO we cannot used 60's technology on a 60's head?

I believe NHRA IS trying to EVEN THE FIELD, just like you want. Toss the cheaters.

But here is the real question Jim. Why do you need to know the spec's? If you cannot modify a head, why would you need a spec?

Re: Great Bend Stock DQ
 

Bob, I can read the rule book very well...the problem is the rule book is not consistent with the real world application by the tech department of its contents and the continous rule changes that take place on the fly that do not address the facts. You cannot just make a rule change unless you understand the ramifications and effect of the new rules on the previously established rules.

As regards to cylinder heads, I can take a pair of cylinder heads, do a competition valve job under the old valve rules and get a specifc volume number...if I take the same pair of heads, put new valves consistent to the new valve rule, I will get a different volume number...these are the facts and those that build engines know this takes place. I could take the heads and surface the intake or exhaust side to get the proper volume numbers...but...which volume numbers I use for a basis for Stock class?

Do you see my point? This does not have anything to do with altering cylinder heads with acid or porting...it is just based on the new valve rule. ...and by the way, I am not condoning cheating...these are the facts. Also, the numbers will vary based on the cylinder head design and the valve size.

Re: Great Bend Stock DQ
 

I fully understand how the new valve rule changes the cc of a head. But as you pointed out, milling the intake or exhaust face and sinking valves for clearance will make the runners smaller. And, the new valve rules will make the runners bigger. Should one balance the other, maybe. But when your runner cc's aproach 10%-15% over the published SS spec, maybe they are just a little to big.

Yes, I do see your point. But do we really know that NHRA does not have spec's? Spec's that they aquired from virgin heads? They have spec's for wheelbase, for example. They are not published, but they have spec's.

Re: Great Bend Stock DQ
 

Stock Eliminator is a bracket race.

Unless you are running heads up, running for class, or setting a record. That's why it is very important to some of use that Stocker heads stay unported!

Re: Great Bend Stock DQ
 

Sometimes even the rule book means nothing. Not trying to change the subject here. But it clearly states that you can only protest a competitor before race day, a friend of mine was protested ON race day and had to tear down. There was no way he could have gotten his car back together for 1st round. Glendora and some of those wizards make it up as we go, again no consistency. I would guess that most racers don't even know the volume of the runners in stock because there is no rule, no listing for each head/engine combo, no + or - , no percentage + or -, so why would anyone care. Castings are castings and each one will be different.

Re: Great Bend Stock DQ
 

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.

Re: Great Bend Stock DQ
 

I believe wheelbase specs are in the classification guide on the left hand side of the page.Heads can vary by 2-3 cc's during production. I have found this on many of the crate motor heads that are new from the factory. I know most hate crate motors, but if this is happening now, imagine what it was 30 years ago at the foundry with less sophisticated mfg procedures. Just my .01 worth. Spent the other penny on gas lol.
Mark

Re: Great Bend Stock DQ
 

Yes, in the early days, core shift was a big problem at foundries. If you are getting that much variation on the crate cylinder heads with todays technology, what can you expect from early OEM castings?

Re: Great Bend Stock DQ
 

Guys:

I have a CNC cylinder head business and have seen variances that you wouldn't believe.
The newer aluminum heads don't vary nearly as much as cast iron but they do vary alot.
I use to run a 428 Cobra Jet Mustang (many years ago) and have seen those heads vary
as much as 6-9 ccs.

S.E.

Re: Great Bend Stock DQ
 

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?