[77 TRASHCAN]

I've read here that when the engine was in early stages, that the initial cam choice was the 041? It was nixed in favor of the 068, for emissions purposes (I wonder if the 744 was considered?).

With such a low compression ratio, I'm sure the 068 worked out better.

Have you thought about another cam choice, possibly the 041 with Rhoads lifters, just to allow the engine to b e built as "maybe" as it should have?

[johnta1]

The SD uses a special cam because of the gear for the distributor is different than normal Pontiacs.
They originally wanted a bigger cam specs like the RA IV but wouldn't pass emissions, etc. (plus only uses 1.5 rocker ratio)


Do you have the PHS for the SD TA?


What is color of interior?

[jhein]

Originally Posted by 77 TRASHCAN

I've read here that when the engine was in early stages, that the initial cam choice was the 041? It was nixed in favor of the 068, for emissions purposes (I wonder if the 744 was considered?).

With such a low compression ratio, I'm sure the 068 worked out better.

Have you thought about another cam choice, possibly the 041 with Rhoads lifters, just to allow the engine to b e built as "maybe" as it should have?

I thought that they did use a cam that had 744 lift and duration but with a different distributor gear?

[mgarblik]

Actually the SD's ended up with the Pontiac "Y" camshaft. It was essentially the 744 cam with the smaller distributor gear. Not one of Pontiac's greatest efforts IMO, but a decent camshaft. Little lumpy idle. Could use some more lift, even with stock heads. Because of the car's value and probably limited use, I am probably going to just use that cam. I have an NOS one. SD cam cores are hard to find because of the small cam gear. I am sure my friend Tim Goolsby at Ultradyne/Bullet could grind a flat tappet cam that would be just as smooth and make 25-30 more HP. But I am leaning toward leaving this one very stock. It's a delicate trade-off when dealing with a more rare car/engine.

Johnta1: I do have the PHS. It is also in the SD TA registry. It has the standard black interior. It was sold in OH to a smaller northern dealership. Too many pages to post, but happy to supply specific info of interest. It's a Norwood car.

[SD455DJ]

Originally Posted by mgarblik

Actually the SD's ended up with the Pontiac "Y" camshaft. It was essentially the 744 cam with the smaller distributor gear. Not one of Pontiac's greatest efforts IMO, but a decent camshaft. Little lumpy idle. Could use some more lift, even with stock heads. Because of the car's value and probably limited use, I am probably going to just use that cam. I have an NOS one. SD cam cores are hard to find because of the small cam gear. I am sure my friend Tim Goolsby at Ultradyne/Bullet could grind a flat tappet cam that would be just as smooth and make 25-30 more HP. But I am leaning toward leaving this one very stock. It's a delicate trade-off when dealing with a more rare car/engine.

Johnta1: I do have the PHS. It is also in the SD TA registry. It has the standard black interior. It was sold in OH to a smaller northern dealership. Too many pages to post, but happy to supply specific info of interest. It's a Norwood car.

Mike, congratulations on getting a great SD! Here’s our experiences with a ’73 SD455. Dan rebuilt my old ’73 SD455 in Dec. 2015 that was a fairly stock rebuild. The bottom end was enhanced with new forged Eagle H-beam rods and .040-over mini-dome Diamond pistons (to get the compression up to 9.4) with the std. ring pack (1/16, 1/16, 3/16), full floating pins, and zero decked with .040 quench. The oil pump was the original 80 lb.-er, so didn’t take advantage of less parasitic hp loss with a 60 lb. pump. The heads were cleaned up with a minimal cut and the chambers measured in at 108 cc’s, new Ferrara 1-pc SS valves and new springs with similar specs to the factory pressures. The original ‘Y’ cam (225/236/115 @ .407”/.407”) and factory lifters were in great shape (46k miles) and reused along the factory 1.5 rocker arms and pushrods. The original cracked factory RA exhaust manifolds were replaced with RARE 2.5 outlet manifolds. The original factory intake manifold and 7043273 Q-jet were reinstalled too.

On a fairly conservative dyno with Pypes 2.5” headpipes (4’ long) the initial pulls started at 390 hp @ 4800 rpm/477 lbft @ 3800 rpm. With jetting and timing tweaks the best numbers were 418 hp @ 5000 rpm/500 ft.lbs @ 3600 rpm, so gains of 28 hp & 23 lbft torque.

We'll be interested to see what a completely factory stock SD455 does on the dyno...guessing 365 hp/465 lbft.

Dennis