Replacement heads on Stocker

[SDT1DYI]

It is curious how NHRA tech dept approves a replacement cylinder head when the runner volumes are considerable larger than their own stated specification. Its been said replacement heads are worth 15-20 HP on a SBC combination. The replacement heads with the HP penalty, seem to produce the same ETs.

Steve Teeter. STK. 6380

[Alan Nyhus]

Originally Posted by SDT1DYI

It is curious how NHRA tech dept approves a replacement cylinder head when the runner volumes are considerable larger than their own stated specification. Steve Teeter. STK. 6380

A good example is the Edelbrock NHRA accepted head for small block Chevy Stockers.

- OEM head: 165 cc intake/65 cc exhaust
- NHRA specs on Edelbrock heads (5 hp penalty) : 172 cc intake/65 cc exhaust
- Edelbrock's specs on these heads: 185 cc intake/65 cc exhaust

When I asked an NHRA Technical official about this, I was told (paraphrasing) that if anyone showed up in Stock with the accepted Edelbrock heads, they would be illegal if they had the 185 cc intake ports. And if the intake ports measured 172 cc, they wouldn't pass because they would have to have been illegally modified (welding) to get down to 172 cc.

[Coleydog]

I think I heard that phrase before, we'll pass it to see what's in it.
Mike

[bubski]

So !! a set of closed chamber iron heads is more expensive than a new set of aluminum heads ?? Whats next ?? the cam is hard to grind with the stock lift ??

[RULER]

This replacement head deal is way out of hand, there are plenty of good stock casting for SBC and oval port and square port BBC, you just have to get your wallet out and there really not that expensive when your building a competitive stock or super stock Engine, And no you can't buy them from jegs or summit.

[Larry Hill]

If anyone needs some 906 cores I have 40 to 50 heads.

[Terry Cain]

Originally Posted by bubski

So !! a set of closed chamber iron heads is more expensive than a new set of aluminum heads ??

Yep

[Bob Mulry]

Hi All,

The reason that most of the replacement heads are only legal in Super Stock is that they have to be modified by filling in the runners to the correct cc's.

You can't weld or use epoxy in the runners of a Stock head.

Combustion chamber volume can also be adjusted in SS and not Stock.

The replacement head just supplies a blank sheet of paper to start with and can be made legal by machining.

Whatever you use it must conform to the NHRA Blueprint Specs including valve size.

Bob

[GTX JOHN]

Larry:

I can match your fifty 906's and raise you 20 more.

About 200 Mopar heads on shelves in my shop.....Some
for 40 years or more!

[Alan Roehrich]

Originally Posted by RULER

This replacement head deal is way out of hand, there are plenty of good stock casting for SBC and oval port and square port BBC, you just have to get your wallet out and there really not that expensive when your building a competitive stock or super stock Engine, And no you can't buy them from jegs or summit.

That's hilarious. How many heads and engines do you build? And just how good are you at welding cast iron heads for Super Stock?