421 SD Tri-Power

Hi, are these engines good? Are they powerful? I saw one on EBay in a 1964 Bonneville, and I was wonderng if that would be good to rebuild and put into my 1979 T/A. Let em know, thanks.

from my understanding (im not an expert, but only a pontiac fan), the 421 super duty is the holy grail of pontiac performance motors, it is to pontiac freaks as the 426 hemi is to mopar freaks. with it being the tri-power option, it might even have the premium heads also. got octane? by posting this message, you may have created new competition on your bidding!

I don't know exactly how big of a deal it would be to install in your Trans Am, because of the number of holes on the side of the block for the motor mounts. I know for sure that the 64 421 will only have 2 holes on each side for the motor mounts. Regardless if you can use in your car or not, I would buy it if you can, I would not pass up on the deal.

If you can install it in your T/A , only a 64 and earlier intake can be used, because of the bolt pattern on the intake to head. The bolt pattern was changed in 65 to the same pattern of the intake that is in your T/A , if it has a pontiac engine.