Heads allowed in modified stock
 

I am looking into running SS, specifically SS/AS, or SS/BS. And I cannot seem to understand what heads are permitted. Here is my specific issues:

The rule book says "all heads must be NHRA-accepted". Then also says "aftermarket aluminum cylinder heads permitted except in CS".

Now, I realize there is an NHRA accepted head list, here: https://www.nhraracer.com/Files/Tech...edProducts.pdf

And I realize this discussion has been extensively discussed here:
http://classracer.com/classforum/sho...t=72138&page=2

However, what I do not understand is what provision allows SB2 heads to be used in these classes? They are not on the NHRA approved list and yet I know they are commonly used. Thanks in advance for any help.

Re: Heads allowed in modified stock
 

Racing cylinder heads that are available over the counter from the OEM are legal and the reason they are not on the list. The list is only for non-OEM aftermarket cylinder heads.

Re: Heads allowed in modified stock
 

Not sure which combination you are considering, but I think the Mopar R5/P7 combo would be a killer in SS/AS, can handle a 4.250" bore and 2.250"+ intake valve with ease.

Re: Heads allowed in modified stock
 

While there are some of these engines in drag cars I have never seen one in a NHRA class car. I have heard of rumors of Comp Eliminator projects but have never seen one that got off the ground.

There was one that ran on Hot Rod's Drag week that ran very well but was not any faster (in my opinion) than an R3/W8 car that was there.

Re: Heads allowed in modified stock
 

Wes Leopold Jr has the answer.

Re: Heads allowed in modified stock
 

I always thought he ran a R4/P5 combo, has he tried the R5/P7?

Re: Heads allowed in modified stock
 

Thank you for the replies.

I'm looking at a AS, BS or CM combo.

Based on the replies an "approved" head is any head which came from the factory, any head listed on the NHRA accepted list and any head which also comes from the manufacturer as an aftermarket head (ie SB2 heads).

Is there any rule or nhra technical bulletin that specifies this? I would just like to feel comfortable about any decisions on an engine by ensuring they are legal.

Re: Heads allowed in modified stock
 

It has always been the policy for Comp Eliminator and Super Stock Modified classes. Any cylinder head that is available through the counter and shown in the racing parts catalog, is deemed acceptable.

As an example, Ford engines in SS/CS, run the Ford Racing cast iron N351 or N352 cylinder head. Ford aluminum heads, can run the C3, D3, and SC1 cylinder heads. The same applies to the Chevrolet splayed valve 12480146/12480147/24502517 or 12480153 heads; SB2.2 part numbers 12480011, or 24502615 Wedge aluminum racing heads or the Vortec Bowtie cast iron heads. Mopar has its own equivalent cylinder heads too. You do not find any of these part numbers in NHRA's accepted product list, however, they are in use.