Alright, I did search for this, and found some threads about it, but it was mostly asking about hardware stuff.

I've got a '91 z/28, 305 TPI, and I can get a running, rebuilt (sub 30k miles) 350 TPI for $200 with a 30 day replacement warranty (local shop, grew up with the owners son). Engine is complete, turn-key, oil pan to intake.

My question is about wiring/ECM. Can I use the wiring and ECM from my 305 on a 350, or will those both need to be changed, or either of them changed?

I apologize if I missed a thread that answers this, I went through 3 pages on my search and couldn't find what I was looking for.

 

Hardware and wiring are identical in any given year. What year is the 350 engine?

Only differences are injectors and computer tuning. Some say the knock sensors were different, but '91/'92 GM shows the same part for 305 or 350.

If your 305 came with single cat, the 350 stuff that year had larger exhaust manifolds, dual cats and larger cat-back.

 

The shop is attached to a 15 square mile junkyard I can pull a 350 from just about any year. I work in a body shop, so I have access to welding materials, so exhaust isn't a problem.

So it's pretty much a plug and play swap? I won't have any issues taking the 305 out, dropping a complete 350 in and plugging everything in?

 

No, from my experience the ecm for the 305 has the fuel injectors running at 19 lbs and the 350 runs at 21lbs. other than a tune for the ecm, all the wiring should be the same.

 

Alright, cool. I can just pull an ECM from a 350 car.

Unfortunately my TC clutch is dead, I'm thinking, so that'll have to be replaced first.

Or at the same time, should be easier with the engine out.

At least it'll give me a chance to throw a better stall/stronger TC unit in there

 

ya ive got a little project of my own i am hoping will shape up here pretty quick. my brother just recked his 91 z28 and he had a 350 with an accel intake and runners on it. he also had a 3.23 posi with disc rear so i am going to swap all that stuff into mine and do a t56 swap while im at it. i was also thinking of doing headers to so that will be much easier with the engine out of the car

 

I'd like to make this one fast, but it's my DD and I just want the right engine in the car

I have my '78 when I want to go fast (built 355, ford 9", 5.10 rear)