Lt1 into 79 impala

[impala101]

Hey guys I was doing some research on swapping an lt1 into my 79 Impala. I have some questions about the wiring involved in the swap.
1) If I would want to keep my th350 trans, would the stock wiring harness still work?
2) Could I keep my stock gauge cluster even though I will have an lt1 motor, harness, and ECU?
3) What for wiring would be involved in the swap? I was thinking of the Painless Performance harness but it says its for the 4l60e tranny. Could I still get the wiring harness and use my th350 trans?

Thanks for the help.

[F.G.]

Thats gonna be a badass ride. I've got a 4 door pillar-less 66 Impala with a 327 and a glide, Still unsure of what I want to do to it, either a stock resto, a patina'd body with a badass motor, or dropping it on a lt1 b-body frame. Good luck on your project man.

[impala101]

Thanks man, the main reason that I want to do the swap is to put a modern motor in it. You just don't see many older cars with newer engines!

[F.G.]

Thanks man, the main reason that I want to do the swap is to put a modern motor in it. You just don't see many older cars with newer engines!

I know man that will be a badass car

[impala101]

Thanks. That's what I'm hoping for!

[impala101]

4317There she is.:drool:

[DMBlack]

Hey guys I was doing some research on swapping an lt1 into my 79 Impala. I have some questions about the wiring involved in the swap.
1) If I would want to keep my th350 trans, would the stock wiring harness still work?
2) Could I keep my stock gauge cluster even though I will have an lt1 motor, harness, and ECU?
3) What for wiring would be involved in the swap? I was thinking of the Painless Performance harness but it says its for the 4l60e tranny. Could I still get the wiring harness and use my th350 trans?

Thanks for the help.

It would be a pretty easy swap no matter the trans you use. If it were mine I would run the 4l60e because of the overdrive and ability to tune shift points through the PCM. If you were to use the TH350 the stock LT1 wiring harness would work fine. You just wouldn't hook up the 4l60e connectors and get the PCM tuned so it doesn't get upset that the correct trans isn't there. You could keep all the stock gauges by using all the correct 79 Impala sending units. If you are using the TH350 your factory speedo will be fine, but with the 4l60e you will probably need to add a small box that takes the vehicle speed sensor signal to spin a motor that turns your speedo cable. Wiring is not bad if you get a complete harness with underhood fuse box. The swap is pretty easy and it has all been done before. Research goes a long way and keeps the surprises to a minimum.

[impala101]

Alright thanks that helps me more! I think I will put the 4l60e trans in. I was thinking and I'm just going to get new gauges. What would be needed for the speedo gauge to work? Like with the 4l60e trans since its an electric gauge (so I think) An with an electric gauge? I'm going to look on google for a diagram if I can find one. Thanks again guys for the help.

[impala101]

I'm still confused about the wiring though. Like if I would get a universial harness from jegs how would the stock accessiaries (turn signals, head lights, ect), connect to the stock lt1/4l60e wiring harness? I just don't understand how it would all be wired up to work?

[DMBlack]

The vehicle wiring harness and the engine wiring harness are two separate wiring harnesses. The only place where the may come together would be the fuse box. The headlights, turnsignals, ect aren't really related to the engine management portion of the car. Do you already have the LT1 engine and transmission? If not I would seriously look into buying a complete donor car. If you were to find a wrecked LT1 Caprice, Impala, Roadmaster, or Fleetwood you would have almost everything you would need to get the swap done. Depending on how hard you look you may be able to find a donor car for the price of that Painless harness. The factory engine harness on any of these cars is pretty simple if you look at a wiring diagram and it comes with an under hood fuse box so it is basically a stand alone deal.

[Dento77]

here are a few wiring links i used when doing my lt1 swap.
http://www.lt1swap.com/lt1_pcm_pinout.htm
http://www.lt1swap.com/95impalalt1.htm
its pretty easy to turn the factory harness into something like the painless one in just a few hours. i'd save the $700 for something else. and like muddyjimmy said above, research,research and more research and if you don't have a donor car, find one! be on the lookout for a ex-cop car, they have the biggest/best cooling system, quick ratio steering pump, gas tank/fuel pump and the lifetime silicon "garden" hoses.

[79LT1Monte]

x2 on the ex cop car. I pulled all of my stuff from a 9C1 Caprice that was a cop car then a cab. There are a ton of then out there and most have a billion miles on them so they are pretty much worthless as far as resale goes. A word of caution double check the vin number you want to make sure the eighth digit is a "P" otherwise you may end up with a 4.3 instead of the 5.7 the vin is a lot easier to get to than the stamping on the back of the block.

[impala101]

Thanks guys. I just have one question that I think will sum up my confusion with the wiring. If I used the lt1 fuse box and plugged in my stock accessories ( turn signals, head lights, horn, ect.) into where the lt1's accessories for the same ones go, would they still work the same? That's my main concern. Thanks again for the support!

[DMBlack]

You have to start thinking in the terms that your car has two harness (for simplicity sake). The engine harness and the vehicle harness. Your lighting, horn, wipers, radio, hvac and such will all work just them same as they do now because you will not have to touch any of these circuits. They will continue to be wired to the current fuse box that they are now. The engine harness will consist of the pcm circuits that will be sensor/computer powers and grounds. The power will come from the under hood fuse box that you will wire in to the Impala's current engine harness. The fuse box will need a couple different types of battery power. Some will be "hot" all the time and others will only have power when the ignition is in the start and run positions. This is where you will have to study the wiring diagrams and research as much as you can. I know that you will not be working on a third-gen Camaro but there is alot of LTX swap info over on www.thirdgen.org (http://www.thirdgen.org) in the ltx/ls1 engine swap section. Read as much as you can and take your time.

[impala101]

Alright I'm pretty sure I know how it all works now. Thanks again. Another question though, for the 4l60e trans, will I have a floor shifter or could I still have column shift? I'm pretty sure that it would be floor.

[DMBlack]

You could still run the column shifter if you want. 79LT1Monte is using his factory column shift with a little modification.

[popo8]

Speaking of retired cop car.... a friend of mine has one... I bet you can get the entire thing for 500 bucks with the car....

[impala101]

You could still run the column shifter if you want. 79LT1Monte is using his factory column shift with a little modification.

Actually I found that Lokar.com makes a column shift kit to mount the 4l60e trans to column shift.

[impala101]

Speaking of retired cop car.... a friend of mine has one... I bet you can get the entire thing for 500 bucks with the car....

I wish I could but I don't have the money, nor would my dad let me get another car. Thanks for letting me know though. I might be in touch with you later down the road though about one.

[popo8]

I wish I could but I don't have the money, nor would my dad let me get another car. Thanks for letting me know though. I might be in touch with you later down the road though about one.


You got it, I dont think its going anywhere.... most of the floor is rotted out....

If your interested, call TONY (owner) of BERKS-MONT TOWING in berks county..... tell him Larry Hanna told you to call.

[impala101]

Alright thanks for the info. Hopefully I'll be in contact with him sooner then later!:hmm:

[impala101]

x2 on the ex cop car. I pulled all of my stuff from a 9C1 Caprice that was a cop car then a cab. There are a ton of then out there and most have a billion miles on them so they are pretty much worthless as far as resale goes. A word of caution double check the vin number you want to make sure the eighth digit is a "P" otherwise you may end up with a 4.3 instead of the 5.7 the vin is a lot easier to get to than the stamping on the back of the block.

Hey if you don't mind could I get a picture of your motor bay? I'd just like to see how you set your wiring up. Thanks you. Oh also how did you wire the stock gauges to work? Like speedo for the 4l60e and the oil temp to lt1 motor, ect?

[impala101]

4347See, I found the there are sensors that would go the ECU. How would I hook up the new gauges? Just let the sensors hang to connect the new gauges? That's what I still don't understand.

[DMBlack]

Your Impala gauges will still use the Impala gauge sending units. Just screw the sending units into the LT1 engine and keep the Impala gauge wiring. The gauge wiring is "separate" from the engine control harness.

[impala101]

Yes but there are connectors in the picture the would go to the motors ECU. would I let those connectors hang/cut off to put the stock gauge senders in?

[94sixspeedz28]

BEAUTIFUL CAR MAN!!!!!!
my brother gave me his '79 Impala 4-door just like that it's a 2-tone blue and i recently swapped the 305 for a small block 400 but i just gave the car back to him since i got the camaro but i think this would be a really nice swap man go for it and keep me updated i cant wait to see it finished