Quote:
Originally Posted by PAUL K
That's good information. Pontiac Engineering sent heads to AFR, Crane and Mullins. They were original service RAIV heads. The AFR were the clear winners and they were too busy to supply heads for Pontiac, so with AFR blessing they had Diamond Elkins copy AFR's work. It forged a long relationship with Elkins and later they helped develop the Turbo Regal heads. I've had heads and blocks come through my shop that came from the Pontiac Engineering Department. They had all kinds of numbers stamped on them. A lot more than just four twos and four ones. They really liked X and /. I've also worked on Pontiac round port heads that were worked on by Crane, Mullins and Elkins. All of them have the company name stamped on the ends of the heads. NONE of them had pushrod tubes installed.
There's a paper floating around written by a Pontiac engineer that used the AFR/Elkins head on the Pontiac flow bench that suggests the pushrod tubes and the port design changes at the flange for the SD head. Both those changes are incorporated into the SD heads.
The Unicorn 1970 RASD head was cancelled long before your heads were cast. We have a knowledgeable member here saying all 197's were cast around the same time. If Russ wanted to work with a special head why would he go with a 197 head? Why not the improved 7F6 head? He would full well know a RAIV head or SD head would kick the crap out of a 197 head. We all know that and he had access to a crap ton more information than we do.
If he used one of the RASD Unicorn heads would we assume the wrong later dates were added just to confuse the issue? Unfortunately we have no pictures of your intake ports but we know your exhaust port exits have been hogged out much farther than anything Crane, AFR, Elkins or Mullins was doing back in the day.
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If you actually go back and read my original post you will see that I never mentioned the year 1970 RASD cylinder head I don’t know were you came up with that.So no confusion on my end.
I would think that if one was developing the 455 SD head that the 1971 455 H.O. head would be a good one to use to get porting flow data.It has the same 111 cc combustion chamber as the 455 SD and the 71 455 H.O. 197 head has better exhaust flow than the 1972 7F6 head right of the bat.The 7F6 head has a restrictive exhaust port (information from page 47 Pontiac Engine Design & Blueprint Assembly book).Craig Hendrickson& Kern Osterstock.You say that the 7F6 head was a improved.In what area just curious.Also you mentioned that the heads being disused just have four 2’s and four 1’s.I guess you didn’t see the RUSS or work order numbers stamped that was mentioned.If you have some pictures of any of the numerous heads that came through from Pontiac engineering myself and others would love to see them for future reference.You mentioned about the exhaust ports on the 197 heads being discussed as all hogged out.I would think gasket matched but not much if any beyond that.I am using stock Ram Air Restoration exhaust manifolds with factory metal gaskets with no overhang in the ports.Also using a untouched factory 1971 455 H.O. intake using stock port Felpro 1233 gaskets.