I inherited an 89 Firebird. It had a half swapped in 350 when I got it. I have since fixed a few of the little things.
I have installed a 350 ESC module, knock sensor stayed with 350. I plan on putting a Police PROM in.
So a couple loose ends. The TBI on it now is from a 350, but the part number is the same as the one on the 305? Not sure if anyone else has ran into this, or if it is even a problem. The cooling fan switch and the Left cylinder head is not there because the motor is out of an 88 Sub which had a mechanical fan. How do I go about installing some kind of switch?
I also need exhaust. I am not much of a welder and would like to find just a bolt together exhaust system. What would be some good exhaust systems to keep this thing legal? It has headers already so I am assuming I would need an exhaust designed to fit with those headers.

 

You can check on the TBI forum, but I believe the only difference between an LO3 TB and LO5 TB is the size of the injectors. Whether that affects the p/n stamped on the TB, I don't know.

Your car should have the fan switch wiring, so just buy a fan thermal switch and install it in the passenger side head and hook up the wire.

Exhaust - what headers do you have? A basically-legal system would be Hooker 2055HKR headers & Y-pipe, Catco 9118 direct fit cat, and 3" cat-back. This all is '86-'90 TPI single cat application stuff, so the "basically-legal" part would be it has A.I.R. and O2 sensor provisions, and connects to a cat - but the C.A.R.B. numbers would only technically apply to the '86-'90 TPI single cat applications. It would pass visual other than that, and should sniff cleanly.

 

Yeah from what I have read the injectors are different, I just wanted to put the old 305 TB back on, put the 350 injectors in it. Reason being is the 350 has a different linkage setup than the 305. Right now my cables are all crisscrossed and/or not hooked up.

I figured I could get a switch for the fans, but I can't seem to find a plug or anything in the head where it should be. I shined a flashlight back there and felt around for awhile but could not find anything.

I have no idea what kind of headers are on it, the PO said they were a gift so he doesn't know either. Any markings I could look for? All I know are they are chrome and already have reducers on them. So would that be stuff I could get from Summit or Jegs?

 

There should be a pipe plug in the passenger head between the #6 & #8 cylinders. It is the same port that is in the driver side head between the #1 & #3 cylinders used for the temp gauge sender.

All of the exhaust stuff I mentioned can be purchased from Summit or Jegs.