Pontiac's SD 455

[king_midas]

Long stroke engines, such as the 455, are hurt much less by the loss of CR than a shorter-stroke variant.

While more compression would give more power in a racing tune, the compromises such as timing curve and valve timing are much less with the low-comp engine. And there's much less of a compromise with the torque curve because of the displacement.

[al8apex]

I worked at the main Pontiac plant complex as a co-op student going to General Motors Institute (now Kettering University) back then (71-74). One of the engineers had a 4 speed Grand Am with a SD in it (his name totally escapes me, not Herb Adams, although he was an instructor at GMI). The engine build area was in a locked cage in the middle of the "normal" engine production area. Apparently too many of the good "purple" parts were walking out the gate ...

You wouldn't believe the cool stuff that was in the engineering recycle bin area (locked cage again) side pipes, Weber intakes, etc, etc.

The one plant had a large scale recycle line ... NOS parts from the parts depot (that were discontinued) were sent down a line and all aluminum, stainless, etc were pulled ... I remember seeing NOS 58 Impala side spears being disassembled to pull the leaping deer (Impala) from the stainless trim. Clocks, trim, etc, etc, tons of NOS stuff being recycled, it was amazing and no, we weren't allowed to "save" anything, even if we had one of what they were destroying ...

[StealthBird]

I remember way back in 1974, my brother had a 69 GTO that he used to run occasionally at a local track in Ontario, Canada. He ran steady mid-14's, no posi, the car had 50,000 miles. I actually have home movies of that car running his friends 69 Dart 340, they were dead even. Anyway, when the SD-455's came out, my brother had NO respect for these 8:1 compression "new" cars, and he thought it was ridiculous how the magazines were touting them as "old Musclecar power". As luck would have it, a brand new Buccaneer Red SD-455 Trans Am appeared at the track one weekend. Since the track did not have board lights to announce the et's, we watched it run a couple times, thought it was SLOW. It made no noise, at least nothing we could hear in the grandstands, as most cars ran open headers back then. We found the car in the pits, and my brother sort of laughed that someone would bring a "new" car to the track. I remember it had a black interior, auto trans, and a/c (which meant it had a 3.08 posi). We assumed it would run high 15's. The driver's side window was down, and it smelled new.

So with about 40 to 1 odds of actually lining up with this lone SD-455 car, my brother actually got paired up with the Trans Am. I was riding shotgun (local track, they didn't care), and my brother told me to watch the Trans Am (passenger side) and tell him how much he was beating him by.

We launched, and the Trans Am immediately jumped about a car length (remember, my brother's car had no posi), we pulled up a little in the mid range, then stayed even on the top end, then the Trans Am actually pulled a little on us. I didn't have much to report to my brother while going down the track, the Trans Am was right there the whole way! We picked up the time slip, and my brother ran a 14.41 at 96 mph, the Trans Am ran a 14.32 at 98 mph.

My brother was stunned, and a little embarrassed. The smog motored, ultra quiet, 4000 lb, brand new car with about 500 miles on the odometer defeated my brothers mighty 69 GTO. When we later found out the a/c equipped cars had 3.08 gears, we were impressed beyond belief. With a 3.42 gear and an open scoop, we figured 14.0's were quite possible.

Simply amazing performance, especially considering all the handicaps the SD-455's were straddled with. The SD-455 is still the most impressive performer of the era in my opinion. It wasn't the fastest Musclecar ever in stock trim, but considering how far it was from being "maximized" from the factory, hindered by a .408 lift cam, 8:1 compression, an EGR intake, not even a cold air induction setup, it's quite impressive.

[njsteve]

[ QUOTE ]
I worked at the main Pontiac plant complex as a co-op student going to General Motors Institute (now Kettering University) back then (71-74). One of the engineers had a 4 speed Grand Am with a SD in it (his name totally escapes me, not Herb Adams, although he was an instructor at GMI).

[/ QUOTE ]

If only that car survived!

GTO DON probably has more info but I believe they made 2 of those before they cancelled the SD engine option in the A-body line and redirected them only into the Firebirds. Cars Magazine voted that car the Performance Car of the Year and it went to print even though the car/option was cancelled.

http://www.abodysite.com/73sd455lit.html

http://www.highperformancepontiac.co...gto/index.html

[PeteLeathersac]

I saw that clone '73 SD GTO in the above link advertised for sale last fall here in Ontario Canada..

Here's another cool article worth reading...

http://www.tachrev.com/GrandAm1973Nascar.htm



~ Pete

[markjohnson]

I tell 'ya the car that SHOULD have been built........the 1974 GTO SD-455. Now that would have been one heck of a car! I've always had a soft spot for those much-ignored Nova-based '74 GTO's. My father actually purchased a very nice '74 GTO with it's standard 350/Auto drivetrain and Shaker hood that was to be my first car for me when I was 16 years old. It was actually much too nice of a car to be handed over to an in-mature driver such as myself as I was wanting something faster and not quite as nice. Anway, it would have been neat for the last year of the GTO to possibly have been the fastest factory one ever built! The '74 GTO DESERVED that SD-455 and it should have happened!

[PeteLeathersac]

[ QUOTE ]
I tell 'ya the car that SHOULD have been built........the 1974 GTO SD-455. Now that would have been one heck of a car! I've always had a soft spot for those much-ignored Nova-based '74 GTO's. My father actually purchased a very nice '74 GTO with it's standard 350/Auto drivetrain and Shaker hood that was to be my first car for me when I was 16 years old. It was actually much too nice of a car to be handed over to an in-mature driver such as myself as I was wanting something faster and not quite as nice. Anway, it would have been neat for the last year of the GTO to possibly have been the fastest factory one ever built! The '74 GTO DESERVED that SD-455 and it should have happened!

[/ QUOTE ]

Right on Mark!.
I always wanted to build a '74 Olds Omega w/ a 455 Oldsie and/or a '74 Buick Apollo w/ a 455 Buick lump too...both stick cars of course!.


~ Pete

[StealthBird]

The SD-455 would have been WAY too much for the 74 GTO, but it's a shame that Pontiac didn't drop in the standard 400 that was being used across nearly the entire Pontiac line. Just with the extra 50 cubes, the car would have been a high 14 second performer.

I like the 74's!!!

[L78steve]

I remember seeing a Pontiac Grand Am ad in 73 bumping the soft nose with a SD455 badge over the fender side marker lamp.