I just purchased an 85 irocz with a 305 tpi motor with a 700r4 trans with over 160,000 miles and have been thinking about swapn' it with a 350 vortec motor from a friend. I know that I will need a new lower intake but what else will I need to round up before I attempt this swap. I mean injector changers and what about the ecm? thanks.

 

Welcome aboard thirdgen.org.

The ECM should be fine. Knock sensor comes to mind as another thing that should be changed.

The '85 has a 2-piece rear main seal, and the Vortec L31 has one-piece. You'll need a 153-tooth flexplate (assuming automatic transmission), used on '86-up 3rd gen f-bodies. New they're about $35-40.

 

will I need to change injector sizes for difference in cubic inches and will I need to change anything else like distributor?

 

The '85 ECM is a one of a kind museum piece do not use it. Besides it will need an ECM with the correct circuitry for the Vortec knock sensor and you already know you need the 350 Injectors.

I would at the very least upgrade to the same year ignition system.

Be sure to measure the depth of intake distributor hole face to bottom of oil pump slot if it's shorter than the distributor from the bottom of the housing where it meets the intake to the end of the key that engages the oil pump you'll need a shim between the distributor and the intake.
if it is shorter and you don't use a shim it will change the base timing every time you crank it eventually it will be so for out of time it will not start, or run properly and stall, no matter how much you tighten the hold down clamp and it will ruin the Dizzy if run that way for too long.

 

Vortec knock sensor? What are you talking about? All you need is a 350 knock sensor.

 

The ECM & knock Sensor from the donor car. There are threads on adding circuitry to make the wrong KS to work with a different ECM by decreasing the sensitivity to knock.

Quoted from AaronIROCZ
Re: codes 32 and 43
You need to hook up the knock sensor from a 91-92 350 tpi f-body car. The computer needs to see a signal from the knock sensor right after startup. I had been fighting this problem with my 91 Firebird Formula, it had an engine from a 88 Formula and had the wrong knock sensor in it. When this code is set, the computer limits how much timing is advanced since it sees a fault with the knock circuit.
If I'm wrong I've learned something new.