Hey,
I am looking at purchasing a 3rd gen for autocross duty. I am strongly leaning towards finding one with the 350, but the auto tranny is a turn off. Which one is better, 305 or 350? I am considering running in SCCA SM class, and it is my understanding that a tranny swap would be legal. Thanks for the input!

 

I would go for the 350, however, third gens did not come with a stock 350 and five-speed. 350 equipped third gens came with 700R4 trannies. I owned one, an '89 Formula 350. A 350 equipped third gen would have to be a custom deal. 350s and the stock Borg-Warner 5 speed, or even the World Class BW 5 speed don't hold up to a 350, so better get one with a T56 or a Tremec. Personally I enjoy autoxing with my auto '97 Trans-Am with an LT1. Wish I would have been into autoxing when I had my '89 Formula 350. The L98 TPI 350 motor is nice and torquey in the low end.

I road race a 305 carb motor in an '84 Trans-Am. It does not have the low end like the TPI 305s which is important to autox, so get a TPI equipped one. The '89 and up WS6 Pontiacs and IROC Zs have the best performance options, brakes, rear ends, etc.

 

one thing to consider is that the 305's did have considerable power. and they do accept mods easily. with a basic intake and exhaust upgrade you'll have considerable power, particularly down low. the TPI motors are torque monsters relative to their HP. i know my old 87 305tpi iroc (granted it was an auto) was only rated at 190hp but it had 295# of torque at something like 2800 rpm. the reason these cars got bagged on for being slow is that they typically ran out of steam at upper rpm's, say above 4500. that slowed them doown in the 1/4mile. but it made them ALOT of fun around town and on short stoplight to stoplight races.

i think a 305 will suit you fine for autoX, you'll have plenty of torque down low. there are also plenty of cheap mods that can be done to increase power. free ram air, ported maf, ported upper plenum, large tube runners w/ matching base, roller rockers, headers, cat back. and also the irocs had damn good suspension from the factory!

 

If I was buying a car for SM I would get a 305 TPI. The displacement limit in SM is 360 ci NA, but SM2's the new displacement limits alow forced induction up to 305 ci. If you deside to move to SM2 or if SM2's limits are applied to SM, you'll be setting in a sweet spot.

 

Maybe. The rule is written in metric terms, and the 305 SBC ends up at 5001 or 5002 cc. Picky? Probably. But certainly protestable. Although many local competitors would probably overlook it, protest would be a virtual guarantee at the National level where contingency $ is at stake; supposedly a non-OE paint job was once successfully protested and upheld on appeal. That was a Stock class, but the philosophy regarding rules that specify definite limits remains the same for all classes.

If you go the forced induction SBC route, do a 3" crank in a 350 block instead. 4942 cc and much better breathing.

Norm