I have an '88 Firebird Formula with a 305 TBI. The motor is shot, so I'm looking into a 350 rebuild. I came across a 70's 350 block, 4 bolt main, 1 piece rear main seal. Would it be possible to rebuild this into a TBI motor, or would it have to be carbureted? What else would I have to change on the car (computer, etc.) to put a carbureted engine in my car?

 

Welcome aboard thirdgen.org.

A 70's 350 would have two-piece rear main seal.

A 70's 350 would have lousy heads (betting the odds).

TBI doesn't much care about what it's sitting on as long as it understands what it is. Since the ECM parameters assume things like displacement, induction and exhaust flow capacity, etc., you'll probably have to do some tuning of the PROM to get it to work correctly. A key part of the engine is the cam - if it has too much overlap or too little lobe separation, the computer will get confused by O2 readings, no matter what you do. The TBI forum is the place to look for all of those details

So, build it so the TBI will be happy, and the engine will work fine. Be aware that the stock TBI exhaust system on our cars is lousy (much like 70's 350 heads), even for the stock 305, so plan on complete exhaust replacement (if it hasn't already been done properly). One detail of a 70's 350 is the dipstick is on the driver's side, while 3rd gen V8's all had the dipstick on the passenger side, and 3rd gen exhaust manifolds get in the way of driver's side dipsticks. Headers is the simple solution to both the lousy exhaust and 70's dipstick location problems.