Stage I heads

[750H.P.V6]

Guy's,

I acquired a Stage I motor thru a deal the end of last year. I was under the impression that it had Stage I heads based on the fact that the Buick Power Source gives a head casting of 25506293 for the Stage I head. The Stage I head is supposed to have no heat risers or EGR provisions, this pair of heads does.

I found some more info that would lead you to believe that all 80-81 production heads have the same casting #. Is it true to say that a Stage I head is nothing more than a production part minus the EGR and heat risers?

Neal

 

[turbobuick]

Neal,
They do have a production head with the same 6293 casting # and it's not the same head. The S1's are easy to identify by the deck surface and the extra webbing in the water jacket were the NA has none, where the turbo 8445 head has a support the S1 head is much larger. The deck surface is thicker, and there are no EGR passages. There are other differences in the S1 head but the biggest is in the design of the intake port floor. It allows for a slightly better intake port especially when ported. I did a lot of flow bench work on my old set and compared them directly to several different types of heads on the same bench same day. I was able to get flow #'s close to what an out of the box GN1 head would flow but with a smaller 1.77 intake valve. This is the reason they worked so well on a 3.8 bore. In all the heads I compared them to (including Terry Ryan's mysterious TSE iron heads with 1.84 valves) I was never able to approach the intake flow #'s of that head with another iron head. Exhaust ports are pretty much identical other than they are pretty beefy heads and you can probably grind more out of the port than a std production head. Sorry bud but they are not S1 heads.
Chris Lyons

 

[750H.P.V6]

Chris,

This is sort of what I figured. I'm glad you could substantiate that for me. I'm going to run them on a stock block motor I have since they are already ported and have big valves etc. Thanks for the good info.

Neal

 

[IMSA34RS]

Stage 1 heads

Chris I had a prevoius thread on the Stage 1 heads vs the 8445 head (I may have to recheck the casting #) What can you pass on to me regarding flow #s on the Stage 1 dead. Thanks, Den

 

[IMSA34RS]

Stage 1 heads

Neal earlier this week I checked the casting #s on what was supposed to be a 1980 3.8. The casting # on both heads was the 25506293 if that helps at all. I just looked in a early build book from Buick for the IMSA RS sedan motors. (3.8) At that very early time they used the part # of 25500001. This high port head was the result of Smokey's work and was put into production in 1979. Den

 

[Intercooler]

Re: Stage 1 heads

Originally posted by IMSA34RS
What can you pass on to me regarding flow #s on the Stage 1 dead. Thanks, Den

Any numbers?

 

[IMSA34RS]

Stage 1 heads

We have just finished up a SBC. It may be a while yet before we do some work and testing on the S1 heads. Den