As a Pontiac fanatic, I can tell you there was only one "size" Pontiac V-8 block. The very early V-8s had different starter mounts and different bell housing flanges, but they were essentially unchanged up to that 1978-79 T/A 6.6 400.
The common reference to displacement changes were made in the main bearing diameters. Very early small displacement V-8s had 2.xx inch mains. As the need for cubic inches developed, those mains were too small to support the larger bore and stroke. The next and longest lived version was a 3.00" main. 350, 389 and 400's shared that main.
As the engines grew in size, a 3.25 inch main was used in the 421, 428 and 455 inch engines. In every case, the bores were enlarged and the stroke lenghtened in the same block.
Pontiac V-8s were engineering marvels for their time. They only needed 10 head bolts. Pontiac developed the ball & socket rocker arm. The cylinder heads had fully machined combustion chambers. There were both open and closed chamber versions.
Best of all for street rodding, these engines all developed a lot of torque down low in the RPM range making them a good choice for harrasing other makes of cars. I still shift my stroked 400 at 5,800 RPM.
The 301 was a ******* engine with only 3 main bearings. If not for the turbo option, these engines were boat anchors.
As far as the death of Pontiac, Pontiac has been dead to me since 1979 when the last 400 was sold. After that, they became glorified rent cars with Buick V-6s and "corporate" V-8s (read Chevy and Oldsmobile engines). There was the Iron Duke 4 cylinder that was Pontiac developed, but it wasn't a V-8.
While the latest Trans Ams with their corporate V-8s became quite fast, being old school, these cars were Pontiacs in name only in my opinion. Even the last GTO was powerful and fast. But when it was parked among Hyundai’s, you really had to look to see that it was a GTO. Too bad.
As mentioned in some earlier posts, GM nixed the racing connections in the early 1960s. Lots of "back door" deals from both Chevy and Pontiac kept the racy images of both divisions alive. Things like the "swiss Cheese" framed Bonnevilles and Catalinas came from Pontiac.
Super Duty and HO engines were also manufactured despite the corporate ban. Some pretty politically incorrect things were done in the name of performance in those days. The first GTO was an option on the LeMans to get around introducing a new model that corporate would have had to approve.
Trying something today like the way they produced a GTO back then would be more criminal than some of the things that has been done on Wall Street lately. Have ever seen a Toyota advertisement done on Woodward Ave?
Those were the DAYS! Every division had a fast car. All were influenced by the GTO. There were even fast Ramblers back then.
