I just came across this site yesterday.....great website! Wish I'd found it sooner...
I'm right in the middle of swapping out the 305 in my 89 RS convertible for a 350. Using the 350 block and heads, Comp Cam (87 vette grind) roller, Edelbrock TES headers + Flowmaster exhaust, no cat, Edelbrock Performer intake, and original TBI. I have a few concerns/questions:
1. I saw on another post that I need to use the bigger injectors from a 350 in the TBI....I understand that. That same post also said I'll need to use the knock sensor and knock module out of the 350 (Rich92RS350's post on May 29 in the TBI board). Does anyone else agree with this? If I leave the stock sensor/module, how will that affect the computer? Which leads to question #2..
2. I'm upgrading the chip to either a Jet Stage 2 or a Hypertech Thermomaster....now I wonder, do I order a 305 chip, or a 350? Anyone have any opinions on either one?
Thanks for your help/suggestions!

 

These ?'s would be better answered on the TBI board.

 

i'm in th middle of the same thing....i talked with my buddies dad who did the swap on his 89 iroc...he said injectors stay, you need a chip....i would have one burned..fastchip.com, or i bellieve jet out of cali does it too....fastchip isonly $350....i can't afford it so i'm gettig caprice chip.....any way all the sensors stay and swap over....so basically the only thing that changes is the chip. hope that helps...and by the way this i the tbi board.

 

Dont forget the knock sensor too

 

if you have a donor car i would take the 350 injectors... i have been looking into this swap and you need to change everything listed above as well as injectors the throttle body is the same though. good luck with everything man...i wish i was doing the same.

 

It'll work with the 305 injectors and 305 knock sensor/module.
It'll work better with the correct 350 injectors and 350 knock sensor/module.
You can compensate some with fuel pressure, but the best way is with the bigger injectors and a chip.
The knock sensor and module wll help with computer control of the ignition advance.If the sensor is tuned to the wrong frequency for the motor, it may retatd timing prematurely and/or allow knock when it should be backing timing off.
-Rich-

 

Thanks for your help and suggestions. I used the 350 injectors and knock sensor/module to be safe, and had a custom chip burned by FastChip. It's all going in this week...can't wait!

 

I am also doing the EXACT same swap, I shattered a piston on the 5 cylinder of my 305tbi, so I got a 350tbi out of a '90van.

GM says you should use a chip, replace knock sensor and install 350injectors, however.................

It has come to my knowledge that at high rpms, the car will run lean, to correct this(a problem which could lead to detonation, meaning KABOOM goes Mr. Piston) you also may need to put a bigger fuel pump in and a fuel regulator.

I know people who didn't do this and their motors worked fine, but leaning out a motor is a very bad, and risky thing to do. Especially if it's considered "NEW" to your car...........
I will be doing these changes in mine, but the choice is yours.
GOOD LUCK!!!

 

RSGuy

I've heard some of the same things. Once I've got a few miles on it, I'll likely add the regulator (I don't expect to be twisting it up too high until its broken in anyway). I just picked it up from the shop the other night (I went with the 350 injectors, sensor and module, with a custom chip). Runs sweet! Only drove it a few miles down to the body shop to get painted...then its over to the tranny shop for a rebuild, then back to my mechanic for the final touches, so...it'll be another few weeks before I start putting some miles on it, but....everything went in just the way it should, no problems at all, and it all seems to work well together. Good luck with yours!