sorry if this is a repeat question, but i havent found an answere and ive looked everywhere. i have a 91 z28 and im doing the 350 swap. i know i have to swap the injectors, esc, and knock sensor but im wanting to know if i can use the 305 coputer and prom and just get a chip burned for a 350? or do i have to get a 350 computer and prom to start with? if so does anyone know exactly where i can get one for a reasonable price? every one ive found was exspensive. or is there another way around it? any help would be appreciated. thanks

i have been searching this on here a lot lately there is a huge thread about it and its answered a few times. From what I gathered you can use the 305 computer and chip but its not recommended to use for very long. You can get a chip burnt (most say burn your own) for the 305s computer. You dont need to replace the whole computer just the chip. or you can use a chip from a 89-92 caprice cop car with a 350.

TPI was only used in F- and Y-bodies (Camaros/Firebirds & Vettes). B-bodies, Caprice et al, used TBI, and those ECM/PROMs will not work with TPI.

You can retune a 305 for a 350. But, since '91 is speed density, trying to run the 350 on the 305 tune is an exercise in futility.

Check the TPI forum for better information.

rechip it it will be fine, there several PCM's that were used. with none specific for 305 OR 350, just know that tpi runs out of air around 5500 r's on a 350

The only thing that you will need to swap to get the 350 dialed in is your chip and fuel injectors. If you just want it to get you from point A to point B for the time being, you can run the stock equipment. I swapped many times to a 350-TPI from a 305-TPI, and the 350 engine ran absolutely fine with the stock 305 prom and 19lb injectors, you just need to raise fuel pressure some. The fueling (19 pounds to 22 pounds) isn't that big of a percentage increase, and all you would need to raise the pressure is an adjustable fuel pressure regulator. The stock prom will 'initially' be fine, it won't be perfect, but it will work. However, eventually, you will want to dial in the engine, and it is here where you will want to focus on burning the right chip to control your fuel and spark....

He is correct, the only place that you will have a problem is in open loop, the fuelling wont be enough for a "good" idle. you will have to babysit it until it warms up and goes into closed loop, then the ECU starts trimming to compensate.

thanks for the help! i did manage to locate a 91 350tpi computer from a salvage yard in wichita kansas for $42. i was suprised since they go for $250 or more on the net. oh well, they must not know what they go for! he said he has a couple of them if anyone else is interested. its KOONS SALVAGE. the number is 1(316)943-2229