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Swapping an 88 GTA 350 into a 305 1988 car

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Old 07-28-2023, 04:23 PM
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Swapping an 88 GTA 350 into a 305 1988 car

So I am going to another state to get a bunch of 3rd gen parts from a guy. He has a complete low mileage 1988 GTA interior and a low mile (68K I think) complete TPI 350 from that same car as well as a low mile borg warner 3.45 posi disc rear. I am thinking about swapping the 350 over to my 1988 Iroc. Is this a direct swap? I know I will have to have a memcal? burned for the 350 and will buy a cold start injector delete plug. I also planned to delete the AIR system and smog pump and keep EGR. My 88 is a 5 speed car if that matters.

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Old 07-28-2023, 06:27 PM
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Re: Swapping an 88 GTA 350 into a 305 1988 car

Yup, direct drop-in.
Old 07-28-2023, 10:28 PM
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Re: Swapping an 88 GTA 350 into a 305 1988 car

Originally Posted by Nutro
So I am going to another state to get a bunch of 3rd gen parts from a guy. He has a complete low mileage 1988 GTA interior and a low mile (68K I think) complete TPI 350 from that same car as well as a low mile borg warner 3.45 posi disc rear. I am thinking about swapping the 350 over to my 1988 Iroc. Is this a direct swap? I know I will have to have a memcal? burned for the 350 and will buy a cold start injector delete plug. I also planned to delete the AIR system and smog pump and keep EGR. My 88 is a 5 speed car if that matters.

Thanks!
do note that the 350 was never offered with a T5 for a reason. The T5 just isn’t built for the torque that a 350 can supply. You probably won’t break it immediately, but if you put slicks out back or try getting some more power up front, you’re gonna end up with some T5 soup. T56 swaps are popular for this reason.
Old 07-28-2023, 10:35 PM
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Re: Swapping an 88 GTA 350 into a 305 1988 car

Originally Posted by codyman125
do note that the 350 was never offered with a T5 for a reason. The T5 just isn’t built for the torque that a 350 can supply. You probably won’t break it immediately, but if you put slicks out back or try getting some more power up front, you’re gonna end up with some T5 soup. T56 swaps are popular for this reason.
Ah! I had wondered. I just picked up an LS T56 but figured I should start looking for an LT1 version or look into a TKX 5 speed
Old 07-29-2023, 08:39 AM
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Re: Swapping an 88 GTA 350 into a 305 1988 car

LT1 T-56s are getting harder and harder to find all the time, if you want one in good condition. There never were all that many, and now that those cars are all over 25 years old, they're vanishing fast. If you REALLY want one, be prepared to scour the Earth actively for all the aprtrs & pieces, and for it to take A LONG TIME to find all of it.

An LS1 one isn't quite as direct a fit, but it's far from impossible. Remember though that those are getting old now too, and may have been used harder, given the more powerful motor.
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Old 08-03-2023, 03:17 PM
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Re: Swapping an 88 GTA 350 into a 305 1988 car

Originally Posted by codyman125
do note that the 350 was never offered with a T5 for a reason. The T5 just isn’t built for the torque that a 350 can supply. You probably won’t break it immediately, but if you put slicks out back or try getting some more power up front, you’re gonna end up with some T5 soup. T56 swaps are popular for this reason.
Yes....and no. T5's are weak, but "not lasting behind a 350" isn't a forgone conclusion. Driven well, they'll last. I had one behind a 400 for over a decade. Always on a real street tire, but I drag-tracked that 1-2 times a week for over a decade, power shifted ever gear, every pass. I broke one, $13 3-4 shift fork, once. Anyone can break anything, of course, but well driven, a T5 can do O.K. for a long time.

I'd still have a back-up/longer term plan, however.
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