Hello there everyone. I have a 86 firebird im putting a small block 350 in. I know the basics that 305 motor mounts will be fine and stuff like that. i found some headers online at summit that are made to fit that engine swap. However, I am wondering, i have a th350 to go with it, how much am i going to need to modify my drive line? and will i be able to put in dual exhaust? will engine to hood displacement be a problem or no? i dont think it would beigns they had 305s in em, but this is going to be carburated with a edelbrock 650 and a edelbrock performer intake. also what should i switch my running gears to?

 

With a TH350, you have to change or modify the transmission crossmember. They are available from the aftermarket (such as TGO sponsor Hawks).

The TH350 also does not have the torque arm mount provision. If you choose parts wisely, you can get the aftermarket crossmember along with an aftermarket torque arm that mounts to the crossmember. Solves both problems.

Other than a car that is used for nothing but racing, I can't think of a good reason to use a TH350. If your car is automatic, then keep the TH700R-4 that is in it now. They can easily be made to handle the extra power of a 350 (especially one with an Edelbrock carb on it) for less expense than the TH350 conversion is going to cost you (to say nothing of the extra expense the fuel you'll be using will cost you in the long run).

The typical 6" tailshaft TH350 is shorter than the TH700R-4, so you'll need a longer driveshaft. The '82-'83 TH200C/4-speed driveshafts were that length, so if you can find one, that'll do the trick. Otherwise, you're looking at buying one (Hawks, etc.) or having a custom driveshaft fabricated.

Dual exhaust on a 3rd gen is an exercise if futility. There simply isn't enough room there to run it without doing something red neck (being a red neck myself, I am allowed to say that). If I can run 11's with a single 3" exhaust (and I do), then you'll be fine with a single 3" exhaust behind a 350 (especially one with an Edelbrock carb on it).

Do you still have the 305 that came in the car? Was it carbureted? Do you still have the factory carburetor system? As you might have been able to guess from my comments so far, I have no love lost for Edelbrock carbs. They are a downgrade from a stock factory carb. If you don't have anything, then an Edelbrock is the cheapest new carb you can buy, but that's as good as you can say about it.