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Old 01-13-2022, 01:45 AM   #10
oldskool
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Default Re: Pontiac 455 hp reduction

Quote:
Originally Posted by ss3011 View Post
Back in the early 80's we ran a 73 GTO in Stock with an NHRA factored Hp at 350 non ram air and 355 with ram air . There was some confusion on the factory HP rating which originally came out at 310 , but was later reduced to 290 . Pretty hard combo to run because the parts are so rare .
Yeah, I've never understood that. I've read that the 310hp rating engine was never actually released to the public. Pontiac decided to put a smaller cam in it, so that it would better meet the emission requirements, at the time. This cam change reduced the advertised hp to 290.

Sorta like SS&DI using an SD455 powered GTO as their cover car one month. Called it "Car of the Year". From everything I've read, the SD455 engine was released to the public ONLY in Firebirds.

https://www.hotcars.com/1974-pontiac...-sd-455-facts/

But, for some reason, NHRA allows the '73 SD455 engine to be used in Lemans, Grand Am, & Grand Prix models. John Clegg actually put one in a GP. And Russ mentioned running one in a GTO. But, as he said, the required factory parts are just too rare & expensive to race, for most Pontiac racers. They're highly sought after by collectors.

I suppose that for the non-Pontiac guys here I should mention a few of the most famous SD455 cars. The 1st is the Herslow & Morlock '73 T/A. It set records in both Stock & SS. Then Phil Szupka raced it for a while. John Clegg bought a new '73 SD455 Formula, & won the D/S class @ Indy with it that year. Later ran pretty strong in SS with it. J.B. Clegg now runs mid 9's with it, which makes it the quickest reg SS Pontiac.

Bob Michael built a '73 for SS. Later sold it to Don Kennedy. Craig Hendrickson of H-O Racing Specialties bought a new '74 T/A. Built a SS/KA out of it & set the record in '77. A few years ago, J.B. Clegg ran some 9.60's in it. So, at that time it was the quickest reg SS class Pontiac, ever. Could name others. But that's just a little Pontiac trivia for off season entertainment.
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Last edited by oldskool; 01-13-2022 at 03:20 AM.
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