Hi,
New member here.....i found this site from chevytalk.org and thought id give it a try. I have a 89 RS with the 305tbi, and im swapping in a pre-86 model 350 4-bolt (basically stock)

First, before anyone flames me, i did a search on the 305 to 350 swap and i still have a few questions. From what i understand so far, i will need to change the following:
injector size
knock sensor
PROM
Which PROM do i need? I saw a post that said one from a 91 Caprice classic. Is that correct?
Can the knock sensor just be any one from a 350 TBI? Will it be compatible with my ECM?
If i use the intake and throttle body from my 305, will the egr stuff work?
Bore the throttle body to increase air flow needs of 350, or just get one from a Caprice or truck? (or Holley aftermarket)

If there are posts already on these subjects (and im sure there are), please link me. Im not opposed to doing research!
Also, this will not be a strip car, just a daily driver. My 305 is smoking like a tar kettle, and i cant justify the cost of rebuilding it when i have a 350 with 500 miles on it sitting on my engine stand.
Thanks in advance!

 

i believe there are posts about this on the TBI forum since you have a TBI injection setup.

 

Have you though about goin to a carb? Might be a little easier and cheaper than trying to change the whole puter and all. Plus there is a more present aftermarket support.

 

Also, what about the water pump? Ill be using a pre-86 350, so i need the reverse flow water pump off of my 305, correct?

 

If you want to keep the serpentine setup. That is what I'm doing. The water pump is really just reverse rotation. It still flows in the same direction. Otherwise if you use v-belts you need the waterpump that goes the other way.

 

Are you using the tbi or going to a carb? Id like to ask you some questions if youre staying with the tbi.

 

No I decided to ditch the tbi and go carb. I sat down and evaluated what I wanted to do and the tbi didn't fit the bill. I was considering going the tpi setup which I can generate more power than a tbi setup.

One thing that weighed in was aftermarket presence. What was readily available. The only aftermarket intake I found to fit a tbi system was an edelbrock which cost almost $400. If you go carb you can choose from a wide selection between $100 and $200. That is just the top. No prom, no sensors, no harness. A lot more to worry about and a lot more cash. If I were going to do any efi setup I would go with a tpi. You can find them complete on ebay for not much money. Not to mention there is more of an aftermarket presence.

Obviously I don't have the answers to your questions, but someone out there does. Best of luck to you!

 

I swapped my 305 tbi for a 350 tbi in my 91, but it was an easy deal because the 350 was also from later than 86. You will save a lot of money and time this way. Just find a later motor if you want to keep the tbi.

 

Well, i already have the pre-86 complete motor sitting on my engine stand, which is why i want to go with it instead of rebuilding my 305. (wouldnt you?) Ive read a post on here or chevytalk.org about a couple of people who only changed the knock sensor and bolted everything else up like it was and ran fine.

Also, if i went carb, id have to buy one of those "lockup kits" for my convertor, not to mention that i believe the tbi would get better gas mileage. I dont think i will be doing any hot rodding with it, its just a matter of already having another engine ready to go.