88 GTA 305 TPI swap to lt1 motor questions
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Junior Member
Joined: Dec 2014
Posts: 24
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From: Siloam Springs Arkansas
Car: 1988 trans am gta
Engine: 305
Transmission: 700r4
Axle/Gears: 4.10
88 GTA 305 TPI swap to lt1 motor questions
hey everyone I have a 1988 Pontiac Trans Am GTA with a 305 TPI. I am doing the lt1 conversion and I'm running into a few troubles.
1.) will the alternator and all of the pullies off of the 305 fit on to the lt1?
2.) do we need to get rid of the 305 wiring or can we use some of it on the lt1? Anyone have a wiring diagram for both of them?
3.)where is the best place to mount the new lt1 computer?
4.)are there any special connectors we need to add to the lt1 wiring harness to fit some of the 305 accessories such as the windshield wipers fuse box connectors etc.
last but not least, any advice I'm going to need that will make this easier?
Thanks everyone!
1.) will the alternator and all of the pullies off of the 305 fit on to the lt1?
2.) do we need to get rid of the 305 wiring or can we use some of it on the lt1? Anyone have a wiring diagram for both of them?
3.)where is the best place to mount the new lt1 computer?
4.)are there any special connectors we need to add to the lt1 wiring harness to fit some of the 305 accessories such as the windshield wipers fuse box connectors etc.
last but not least, any advice I'm going to need that will make this easier?
Thanks everyone!
Joined: Sep 2004
Posts: 5,906
Likes: 240
From: Chicagoland Suburbs
Car: 1989 Trans Am GTA
Engine: LT1, AFR 195cc, 231/239 LE cam.
Transmission: M28 T56
Axle/Gears: 3.23 10bolt waiting to explode.
Re: 88 GTA 305 TPI swap to lt1 motor questions
hey everyone I have a 1988 Pontiac Trans Am GTA with a 305 TPI. I am doing the lt1 conversion and I'm running into a few troubles.
1.) will the alternator and all of the pullies off of the 305 fit on to the lt1?
2.) do we need to get rid of the 305 wiring or can we use some of it on the lt1? Anyone have a wiring diagram for both of them?
3.)where is the best place to mount the new lt1 computer?
4.)are there any special connectors we need to add to the lt1 wiring harness to fit some of the 305 accessories such as the windshield wipers fuse box connectors etc.
last but not least, any advice I'm going to need that will make this easier?
Thanks everyone!
1.) will the alternator and all of the pullies off of the 305 fit on to the lt1?
2.) do we need to get rid of the 305 wiring or can we use some of it on the lt1? Anyone have a wiring diagram for both of them?
3.)where is the best place to mount the new lt1 computer?
4.)are there any special connectors we need to add to the lt1 wiring harness to fit some of the 305 accessories such as the windshield wipers fuse box connectors etc.
last but not least, any advice I'm going to need that will make this easier?
Thanks everyone!
Start digging in.
https://www.thirdgen.org/forums/engi...questions.html
Re: 88 GTA 305 TPI swap to lt1 motor questions
1) No
2) Reuse some of it
3) In the old ECM location
4) Read the wiring stickys laid out in post 3
I recommend you read the sticky a few times and figure out why each of the main points are covered in such detail. Its not a hard swap, but there are quite a few hurdles to overcome and you need to know why these need to be dealt with before starting
2) Reuse some of it
3) In the old ECM location
4) Read the wiring stickys laid out in post 3
I recommend you read the sticky a few times and figure out why each of the main points are covered in such detail. Its not a hard swap, but there are quite a few hurdles to overcome and you need to know why these need to be dealt with before starting
Supreme Member
Joined: Jul 2007
Posts: 1,293
Likes: 6
From: Howard Lake, MN
Car: 86 Camaro
Engine: 355- hopefully a 5.3 this summer
Transmission: 700r4
Axle/Gears: 3.42
Re: 88 GTA 305 TPI swap to lt1 motor questions
the engine harness is separate from everything else in the car: the gauges, starter, wipers, and, dome light, power windows, headlights, and anything else on the car have absolutely nothing to do with the engine install.
the ecm will go wherever your harness dicates: if using a Caprice LT1 and harness, the ecm will be behind the driver's side headlight. if using an F body engine and harness, it will be on the passenger side strut tower somewhere... i don't know where the Vettes put it... aftermarket harnesses allow you a lot of room to decide where you want it, but the stock ecm lives comfortably under the hood somewhere.
if running a Caprice harness, you really should go thru and take out all the extra wires.. they bundled the engine harness in the front lighting harness on those cars for some reason, so the headlight, turn signal, horn, and whatever else is in there and needs to be removed to make it into a standalone harness. it's not hard, but it takes time and when you get done you wind up with a self contained harness that only requires a few wires to be hooked into the car itself.
the ecm will go wherever your harness dicates: if using a Caprice LT1 and harness, the ecm will be behind the driver's side headlight. if using an F body engine and harness, it will be on the passenger side strut tower somewhere... i don't know where the Vettes put it... aftermarket harnesses allow you a lot of room to decide where you want it, but the stock ecm lives comfortably under the hood somewhere.
if running a Caprice harness, you really should go thru and take out all the extra wires.. they bundled the engine harness in the front lighting harness on those cars for some reason, so the headlight, turn signal, horn, and whatever else is in there and needs to be removed to make it into a standalone harness. it's not hard, but it takes time and when you get done you wind up with a self contained harness that only requires a few wires to be hooked into the car itself.
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