Mikes reply:
"Aluminum Exhaust Manifolds"
The Mighty 421 Super Duty Engine. The differences on this engine are the Alternator and brackets. 1962 421 SD engines were equipped with a generator. This engine is also equipped with Aluminum Exhaust Manifolds which would simply melt if subjected to ordinary street use due to the excessive heat. The engine was rated at 405HP, but it's true output was much higher.
https://www.oldride.com/library/1962...uper_duty.html
https://www.jalopyjournal.com/forum/...perts.1051192/
https://youtu.be/kQS4fRr_Z7M
https://youtu.be/Jed0xGPH_HM
https://www.jalopyjournal.com/forum/...perts.1051192/
One other fact about the SD's that probably will not play well on this forum. Pontiac engineers tested the legendary TriPower, even casting an aluminum manifold for the SD, and found it was not competitive; and immediately discontinued the TriPower. So, the SD's used, depending on the venue; (1) a single four-barrel, (2) dual four-barrels, or (3) a single three-barrel. TriPower's were relegated to the non-racing engines to customers that believed the hype.
I don't recall an aluminum tri-power manifold for the SD but for sure it was catalogued in the early sixties. I think it was done for the 389 HD. The Heavy Duty (HD) program was the forerunner to the SD. Pontiac was heavily into NASCAR with Smokey Yunick, Ray Nichels and others and they developed suspension and engine parts for oval racing in addition to the drags. HD parts were strictly over the counter and as a result not legal for S/S, but there was also O/SS then, maybe that stuff was legal for the Optional/SS cars.
HD stuff included solid lifter cams, aluminum 4 bbl. and 3-2 manifolds, dual point distributors, heads with bigger ports, valves and screw in studs with guide plates. Then there were special spindles and metallic brake packages, clutches and flywheels, and I'm sure a lot more.
https://www.jalopyjournal.com/forum/...#post-11794806
https://www.jalopyjournal.com/forum/...-ever.1041715/
https://www.jalopyjournal.com/forum/...perts.1051192/