[MrPbody]

While I understand your sentiment, it IS sentimental. "Pre-smog" would be '64 and older. ALL 400 production engines had to meet emmission standards, at least in California, and "Federal" after '67 ('67 was first year of production).

The first GTO or Firebird equipped with an engine larger than 400 CID was 1970. The '70 455HO was a D-port design (advertised at 10.25:1 compression, the ONLY "high compression" 455), using the 068 cam, making 370 advertised HP and 495 advertised lb. ft. The Ram AIr IV 400 had the same advertised HP, but torque was 435. It (RA IV) was a much more powerful engine at higher revs. Unfortunately, GM forced Pontiac to use those gawd-aweful cast connecting rods, making a GOOD high revver impossible. Ram Air V ("tunnel port") was the shizzle... BUT... None were released in production cars. Too bad...

Beginning in '71, rating methods changed, making 455HO yield 335 HP. A '71 T/A was available with this as the ONLY engine option. Same in '72. My '70 Judge Ram Air III car (366 HP 400) would run along side the '71 GTO w/HO, but the T/A would run away and HIDE from the GTO. When they reduced the compression ratio and horsepower ratings of 455, they did the same thing to 400.

Don't misunderstand me here. I LOVE the 400 Pontiac. Absolutely the best overall engine of the muscle car "era". But certainly not the most powerful, and unless properly prepared, not the most durable (thank GM politics and Chevy for that). Once properly built, 400 is an excellent all-around engine. We have several customers with them running solid 12 second cars in street trim. Even had a couple go in the 10s with a small "hit" of nitrous.

We recommend 400 for most road racing or circle track applications for the ability to rev, AND for the lower amount of low-end "grunt". Coming off a corner is a big deal to those guys, and a high torque engine will tear the tires off at lower speeds. But don't discount the 421/428 combo. VERY effective.

Lastly, considering the engine has been out of production since 1978 (those installed in '79 models were "leftovers"), the term "stock" is of little relevance.

PAX

Jim