Pontiac's SD 455

[southernfriedcj]

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...and are much more sought after then the much more garden variety 454 4 barrel T/A's and Formulas of that year

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A factory 454 Trans Am is indeed a rare Bird!

[Keith Tedford]

I think I read somewhere that the very early road test SD cars were ringers with a different cam. They were running mid 13s when anything else in '73-'74 couldn't get out of its own way. It seems that even the production ones ran pretty well. In the sixties, Pontiac wasn't above a little creative advertising as in the Ferrari-GTO road test comparison so nothing surprises me there. In '68, I had a warmed over RA 400 Firebird, later a '69 GTO, and more recently a '72 Lemans Sport with a warmed over '70 455. These can be mild mannered, smooth as glass to drive and still run 12s with very little work done to them. Not bad for a basic design from the '50s. Those 454 Firebirds were built here in Canada where they built the 302 Firebirds that Titus raced in the TransAm series in the late '60s.

[L78steve]

This is correct the early test cars got the 041 spec. cams installed. All were supposed to get that cam but emissions nixed it for the 744 spec. cam instead,which is still no slouch.The board on the shaker and the crossflow muffler system killed the performance even more,I'm sure the test cars had this opened up. The quad air valve would never fully open in stock form.[ QUOTE ]
I think I read somewhere that the very early road test SD cars were ringers with a different cam. They were running mid 13s when anything else in '73-'74 couldn't get out of its own way. It seems that even the production ones ran pretty well. In the sixties, Pontiac wasn't above a little creative advertising as in the Ferrari-GTO road test comparison so nothing surprises me there. In '68, I had a warmed over RA 400 Firebird, later a '69 GTO, and more recently a '72 Lemans Sport with a warmed over '70 455. These can be mild mannered, smooth as glass to drive and still run 12s with very little work done to them. Not bad for a basic design from the '50s. Those 454 Firebirds were built here in Canada where they built the 302 Firebirds that Titus raced in the TransAm series in the late '60s.

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[StealthBird]

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I think I read somewhere that the very early road test SD cars were ringers with a different cam.

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The original road test cars were not ringers, they were pre-production models that used the RAIV cam. This was the intended setup for the SD-455. The SD-455 story is fascinating, and a tribute to how grit and determination by a few engineers allowed these cars to be built.

The pre-production SD-455 Trans Am's were built with the RAIV cam, and they passed the EPA emissions test. But the EPA discovered that Pontiac engineers rigged the EGR valve to close after approximately 50 seconds, which just happened to be a few seconds after the standard EPA emissions test was complete. The government was not amused, and they failed to certify the SD-455 for production. Pontiac then had to go back and re-do the setup, elminating the RAIV cam, assigning a new casting number to the intake manifold, and get the whole thing re-certified by the EPA. This is what caused the SD-455 introduction to be delayed, so these cars did not appear until very late in the 1973 model year. Also, because the certification process was so lengthy, and anything from a simple air cleaner change to hood change had to be re-certified, Pontiac decided to build the Formula SD-455 cars with the Trans Am hood, which had already passed the EPA tests (that's the reason the Formula SD-455 cars did not come with the Formula twin-scooped fiberglass hoods).

But in the meantime, the pre-production SD-455 Trans Am's made the rounds in auto magazines, and ripped off mid-high 13 second blasts completely stock (with the exception of an open hood scoop). Amazing performance for an engine with 8 to 1 compression, in a car weighing 3800 lbs, with a steel intake manifold, 3.42 gears, restrictive exhaust, an auto trans, and stock tires.

But when Pontiac had to remove the RAIV cam and put in their boiler plate special .408 lift cam, the cars slowed to around 14 seconds flat in the 1/4 mile. Still amazing performance considering all the other handicaps mentioned above. No cars were delivered with the RAIV cam. The SD-455 engines were quite special, and they weren't simply parts thrown onto a standard 455 engine. The SD-455 used a special block, connecting rods, distributor, carb, intake, heads, and camshaft.

[1970Bluel78]

How about a 1973 GTO with the SD-455 ?? Cars Mag, car of the year. I was told 3 mules were made but the car never saw production. Too bad

[Xplantdad]

I'd rather have a Formula 455 SD...One of CHarley's friends had one...it was blue!

[markjohnson]

I absolutely LOVE the Formula SD455 cars!

[1969z280]

Check this one out:

Mecum 1973 SD Formula