So i got my motor but no harness so ill be getting a new one (already on the case but not ordered yet) any advice at all will be great thanks a bunch. It's 2wd.

 

Which LT1 are we talking about here. The older 350 style or the newer gen-V 6.2l? Big difference lol

 

It came from a 94 impala 350 style its a 5.7

 

Ah okay lol, just wanted to clarify.

It shouldn't be that much more complicated than a standard Vortec 350 swap. From what I see, most people reuse the original 4.3 harness when performing that swap and just add in a couple extra wires for the extra injectors. However the Vortec 350 uses a similar spider injector assembly to the 4.3, so it's a little more localized when it comes to adding in the extra wires. Being that the LT1 has true multiport injection, you'd have to extend all of the injector wires to reach the injectors. Time consuming, not super difficult, definitely cheaper than buying a new complete harness... Most everything else should be nearly identical though when it comes to the sensors and so on, as in the end it's still just basically a 4.3 block with 2 more cinders added on. Fairly certain you could even reuse your original computer and just had it reflashed. If the older 2000 style computer can't, you could always change the plugs over to use a newer style 411 computer which I KNOW will run a 350. Hell, the 411 was used to run all the way to the Gen III LS (with crank and cam signal converters, they can run Gen IV LS as well).

 

Sick! Thanks man the people I talked to in person tried to make it seem like this swap was going to be rocket science this is my first swap but I'm not green when it comes to turning wrenches. I know the motor was already paired with a the same tranny that is in my jimmy so that was a huge relief. If any thing else comes to mind man I'll be here I still got some clean up work to do so I'll be back with more questions im sure lol

 

Yeah your original 4L60E will pair up to it no problem. GM use the same basic transmission all the way up into 06-07 for the full size trucks with V8's bolted to them.

I would never try to turn anyone away from this forum, but another great source of info on the swap might be the V8S10.org page. Lots of good info there, and I'm sure there's people there that have done an LT1 swap themselves and could give some great pointers.

 

Thanks bubba great idea never want to put all your eggs in one basket

 

Red and Mitch. I have come in late to this post. I want to ask for a clarification. I believe that there were two different Chevy 5.7L engines in 1994. I have a Chevy 1994 Impala SS with the 350 cu in / or 5.7L engine and it was called the LT1. It had some major differences from the other 5.7L V8 engines. The Impala SS engine was a reverse flow coolant system and had an Opti Spark distributor. It did not have the spider injection system like the 4.3 L Vortec V 6 or the 5.7L Vortec V8. Please note that the LT 1 was used in some Impala SS and some Camaro's and the Corvettes.of that era. To make it more interesting, the LT1 designation has been used again for a newer version of the Corvette engines. That is also a diff. engine. But we are here talking about a 1994 Chevy Impala SS engine. with the LT1 designation. You aren't going to be able to use the 4.3 L V6 PCM. for that.You will need the 94 Chevy Impala SS LT1 computer and harness. At one time you could buy a complete PCM, harness and 4L60E trans /hate to bring this up, but it is also diff. from the 4.3 L 4L60E trans.......... So if you are using a Impala SS LT1,you will need the SS 1994 LT1 harness and the PCM and some trans concerns as well. .

For the Chevy History buffs.
The original LT-1 was used from 1970 to 1972. Pls note the 'hyphen'
Then the LT1,/ no hyphen/ was used for the new designed 5.7L from 1992 to 1997 in some sport models including the Impala SS from 1994 to 1996.

 

I have the optispark distributor type 5.7 brotha thank you so much for the info if you wanna share more info im more than willing to listen I love learning. Now I had already planned on buying a new harness but I didn't know about the pcm glad to learn it. Also I had planned on pulling the tranny anyway to upgrade the internals (torque converter etc.) Question i tried pulling the distributor without removing the crank pulley is that going to be possible or should I just remove it

 

Also i forgot to ask but what type of trans issues do you think ill run into can you point me in the right direction