5.3/4l80e help

[volleyballer13]

Been lurking on here for a while trying to figure out what to do. I recently purchased a 1970 Blazer, factory 2wd, with the 307/350 combo. Attached a couple pics of how I bought it and how it looks now. I just purchased a 5.3 out of a 2005 Tahoe that had a 4l60 behind it. I didn't get the trans with the engine. I have a build 4l80 from another project that I would like to use behind the 5.3. My question is how difficult to put it with the 5.3 in the blazer? What do I need? Or should I go with a 4l60 since that is what was behind the motor originally? I have been searching, but get conflicting info or info that is about swapping from a 60 to an 80 and didn't know if that would apply since neither trans has been in the blazer. I know I may have to get my driveshaft shortened, and need to get the computer reprogrammed. All the stuff to do with converting to EFI, I understand, it is just about the trans. Any and all help would be greatly appreciated.

[truckdude239]

You will have to add a second speed sensor to the harness and have the computer flashed for a 4l80e

[littlevictories]

yeah i think ^ that's the most legit way to swap
more info on that here: http://ls1tech.com/forums/automatic-...l80e-swap.html

here's some info from denmah's site
https://sites.google.com/site/sloppy...-ls/4l80e-info

i swear i have read about a swap that didn't require a segment swap in the computer, but hell if i can find that info now

[656mx]

I have a 80 behind my 5.3. Not a hard swap to do. Re pin trans plug, add vss, 6.0 crank spacer and bolts. I had to oblong the holes in 5.3 fly wheel for tork converter but i think you can use one from a 6.0 instead. I was going from a 400 to the 80 both were bolt on yoke so i just had to shorten my driveshaft 2 1/2 in. 80e trans segment swaped into pcm

[volleyballer13]

Thanks for all the info guys! When you say re-pin, you mean pull the wire from the wrong pin and insert into the correct pin, right? Just want to be sure. Was starting to get worried when I heard about people having to pull all the extra wires and basically rebuild the wiring harness.

On a side note, I thought I knew more about the EFI swap than I do I guess. I have been doing some reading and have determined that mine is a returnless efi system. So, does that mean I can use my existing fuel tank and just use a different sending unit that will have the correct pressure?

Thanks again for all the help. Also, if you know of a thread that will answer my questions without too much typing on your part, please point me in that direction. I just couldn't find the info I was looking for, or maybe I was asking the wrong questions.

[656mx]

http://lt1swap.com/ has lots of good info and ls1tech.

[Clyde65]

If your just going to cruise in the Blazer, leave the 5.3/4l60e as a match, makes things easy. If your going to cam it or turbo, then the 4l80e is a better choice.

What are you using the truck for?

[volleyballer13]

Clyde65,

I am planning to mostly cruise it, but already have a cam for it. Goal is 400+ at the wheels. The reason I am wanting to go the 4l80 route is because I already have a built one, so don't have to buy a trans, and then have it rebuilt.

Russell

[volleyballer13]

Thanks again, for all the info from everyone.

Russell

[68c10airstream]

Hi Russell, i haven't paid a lot of attention on the 4l80 swap, but one item that i remember is a possible lack of room in the floor tunnel area. The trucks have a low hump and a high or tall hump. I believe the truck guys bolt in the high hump for the bigger 4l80. I assume the blazer has a removable trans hump. I'm running the factory low hump in my 68c10 with a 4l60 and its ok, close enough though. Great help on here, and some guys are modifying the stock tank for a add-0n low sump well area as a pick-up point for an external fuel pump i believe. Good luck, Brian Fuller