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305 TBI to 350 TBI/Carb Confusion

Old 07-05-2014, 12:49 PM
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Car: 1988 Pontiac Firebird
Engine: LO3 5.0 (305) TBI
Transmission: 700R4
305 TBI to 350 TBI/Carb Confusion

I have an 88' firebird with an ailing 305 that needs an overhaul. I decided to swap it out with a 350. The 350 was out of a boat that one of my neighbors had rebuilt. Its .030 over bored with a mild cam and machined stock heads. I want to go with TBI but will choose to go with a carb if it gets too complicated. If I decide to reuse the 305 TB, I will need to change the injectors, retune the 305 PROM to work with the 350, and connect all the appropriate sensors. Is this all that I will need to do to get the 350 TBI running properly? Will i need to upgrade the stock fuel pump as well?

On the other hand, If I decide to go with the carb will I only need to get a fuel pressure regulator to reduce the fuel pressure for the carb?

I have been reading the myriad of threads on the 305/350 swap and am now completely confused. This is my first swap and would appreciate any help. Thanks again.
Old 07-05-2014, 04:36 PM
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Re: 305 TBI to 350 TBI/Carb Confusion

TBI is SUPER EEEEEZY to swap to a 350.

Use your existing intake; get the TB (incl injectors), chip, knock sensor, and ESC module out of a 350 TBI vehicle.

Too simple.
Old 07-05-2014, 05:00 PM
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Car: 1988 Pontiac Firebird
Engine: LO3 5.0 (305) TBI
Transmission: 700R4
Re: 305 TBI to 350 TBI/Carb Confusion

Thanks for the reply. I have a couple extra questions.

Will the stock in-tank fuel pump work with the 61lb injectors?

Is the "chip" basically the entire ECM unit under the passenger side dash?

Thanks again.
Old 07-05-2014, 07:39 PM
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Car: 1989 camaro rs convertable
Engine: 305 tbi
Transmission: 700r4
Axle/Gears: 7.5"3.42 gears forth gen 2000 camar
Re: 305 TBI to 350 TBI/Carb Confusion

https://www.thirdgen.org/forums/tbi/...-350-swap.html
Old 07-06-2014, 09:27 PM
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Car: 1988 Pontiac Firebird
Engine: LO3 5.0 (305) TBI
Transmission: 700R4
Re: 305 TBI to 350 TBI/Carb Confusion

I have one last question here. I was reading the sticky on the dreaded 8063 ECM in the 88 firebirds and I am wondering if I should swap out the whole ECM? If so, what should I put in its place?

Thanks for all the help!
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