just blew the engine in my 87 trans am 305 tpi and am installing a new engine but want more power can anyone tell me what needs to be modified if i change to a 5.7 instead of a 5.0 also am thinking about a 383 stroker any success in putting the tpi on top

 

Your 87 uses a Mass Air Flow sensor which directly reads the amount of air going into the engine. As such, you can put a 350 under it and the MAF will compensate well enough to run the engine acceptably and get good performance. That is, until you max out the flow of the small 19lb stock 305 injectors, but that's a consideration for later.

Ideally you want injectors better suited to a 350 (usually around 24 lbs or so for a mild streetable 350) and a chip burned to work with them.

MAF systems don't take kindly at all to mismatches between the chip programming and injector size. In other words, since your 305 chip was designed to work with 19lb injecotrs it's best to continue to run them together. Don't drop in 24lb injectors and keep using the stock 305 chip designed for 19lb units. You won't get good results.

Back to the 19lb injectors- if you get up over about 300-325 HP they will be pretty well maxed out at WOT/high RPMs. At that point they will be essentially open all the time (approaching 100% duty cycle). If you have plans of going beyond that with the new 350 then it would be best to get the larger injectors AND A CHIP TO MATCH at the same time right up front.

Personally, in my limited experience with MAF-TPI systems, I like to run the stock chip and stock sized injectors just to get the engine up and running and broken in, putting a few miles on it. THEN I do the chip/injector swap. The number of times I've found the aftermarket chip to be burned with bad programming is the reason why. Stock chips/injectors are at least a "known quantity" and will usually start and run the motor reasonably well(if it's a "streetable" motor- no big cam). Make sure everyting checks out OK and then try out the aftermarket chip with the matching injectors and see how it does.

 

I'd go with a 383 because I doubt it costs much more to go right the first time. I got my EPROM custom burnt by www.fasterproms.com and like it. They send you a chip they burnt to your specs and have you take readings and they reburn it, take more readings and then do a final burn. Cost for this is $350 and if you need to repeat process again, it is $150

 

The proper way to replace a 305 with the 350 is to replace the rest of the stuff that was different. This means:

injectors
PROM (the chip)
knock sensor
ESC (electronic spark control) module.

The ESC isn't really much different from the 305 to 350, so most people don't change them. The 350s used 22lb/hr injectors, which are pretty easy to find used at good prices. You could use a chip from a stock 87 350 f-body, or you can take the initiative and start burning your own. The knock sensor is different and will effect the performance if you dont' change it.

If you go to a 383, you might be able to get away with the 22lb injectors if you crank the fuel pressure, but you'll probably be better off with bigger injectors. You'll also be much better off with a custom chip. Again, doing it yourself is the most cost effective, but obviously there's a learning curve associated with doing it yourself.