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1986 Blazer

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Blazerride22

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Hello All! I was hoping to get some folks that have some experience on an LS swap on my rig. I’ve never done an LS swap but picked up and LS1 that’s complete with a 2WD 4L60 transmission.

The blazer is a totally stock 305. Runs great except for having a 305! Wanted to see if I can use the transmission or do I need to get a L480? Just general info on how to make the swap would be great. Thanks in advance and happy new year!
 
Welcome!

LS swaps into K5's are fairly commonplace now. Many, here including myself have done one. Its so common, there are dozens and dozens of build threads documenting the process. Search and you'll come up with days and days of reading material.

But the cliff notes version is:

Motor mount adapter brackets (many to choose from)
LS truck manifolds or headers to fit
TBI fuel tank with updated ep381 pump (or similar)
Pruned stock LS harness or Standalone setup.
Trans of your choice, but a 700r4 will require a specific TV cable setup. The easiest route is a 4l60e or 4l80e that might come with the LS engine.

Many of the build threads go much deeper in detail down to part numbers and reasons why they did what they did.
 
Like Zoo said each one is different, I would look at some of the builds here and ask questions. We are happy to help you with tech questions.
 
Thank you guys for the info. Was hoping that you all might be able to point me in the direction of one of the better build threads as well as answer a couple of questions I have.

1). I currently have the factory Transfer case. Will that work with the LS Swap?

2). The LS came with a 4L60, is that my best direction or should I try to find a 4L80 instead?
 
Your best bet is to find a 4x4 4L60
Or 4L80….not the 2wd one, you can use one of the right side drop 32 spline input t cases like a 205 or 208 if you go with a 4L80…..I don’t know much about adaptability to a 4L60
 
A 27 spline input was available on 208 and 241 transfer cases. They matched up to 700r4’s which happen to be the earliest version of the 4l60.

The later 4l60e versions do require a vss output on the t-case. The only pass side drop t-cases we’re the 241 and 205’s from ‘90 and ‘91 squares. Though you can retrofit a vss to the earlier versions including a 208 by getting the parts from:

www.walterseandp.com

Custom Automotive Solutions | Walters Engineering And Performance | Hope

Walters Engineering and Performance LLC Provides Custom Powertrains, Automotive Mechanical Design, Powertrain Diagnostics and Tuning, and Aftermarket Part Installation
www.walterseandp.com www.walterseandp.com

By being able to retrofit you aren’t locked into trying to find a two year only version.

I’ve tried the signal generator units on a buddy’s truck and while it worked and he was able to maintain his cable speedometer the box required a lot of fiddling and I couldn’t get it to be accurate. The more I adjusted to get the trans shifting right, the difference between actual speed and what the pcm saw got wider apart. The issue arose on the highway that he was hitting a speed limiter at a ridiculous low speed of 70mph (actual, measured with gps) when the pcm thought it was going 90mph+.

Fed up we changed direction and dropped the Walters parts into the 208 and the trans shifts correctly an doesn’t hit the speed limit function prematurely. Though the factory speedo is currently inoperable with no cable driving it. We found him a 90-91 cluster, drac module and the wiring to put a working speedo back into the truck that still looks factory.
 
Get a 4x4 4l60e from the same year vehicle as your engine if possible. Use your np208 and Advanced Adapters part #ADD-50-0405E. It’s a thin adapter that goes between the trans and the factory blazer adapter with the legs that mount to the xmember. Much easier and cheaper than trying to source a 241c with factory VSS. It comes with a ring that installs on the output shaft of the trans and a VSS sensor that mounts in the adapter. These work fantastic in all driving positions 2hi-4lo, and allow you to keep your cable speedo. I’ve used it on 3 swaps, and getting ready to do the 4th. Haven’t had the first issue with any of them, installed correctly. Holler if you have other questions, I have a fairly complete parts list for squarebody LS swaps.

Edit- when you say Ls1 do you mean an actual 5.7L LS1 or a first gen 5.3 truck motor?
 
I've been pretty slow on my progress. I've taken the advice you all gave and bought a 4L80 to use. I also rebuilt my factory transfer case. My engine is almost finished and should be ready for pick up in the next couple of weeks. That brings me to a question I have on where to buy the LS swap parts. Motor mounts, gas tank's that sorta stuff. I had spoken with a guy at BRPhotrods.com They specialise in LS swap parts and are very helpful. Anyone used them, are they as good as anyone for parts?
Thanks,
 
76k5blazerr said:
Get a 4x4 4l60e from the same year vehicle as your engine if possible. Use your np208 and Advanced Adapters part #ADD-50-0405E. It’s a thin adapter that goes between the trans and the factory blazer adapter with the legs that mount to the xmember. Much easier and cheaper than trying to source a 241c with factory VSS. It comes with a ring that installs on the output shaft of the trans and a VSS sensor that mounts in the adapter. These work fantastic in all driving positions 2hi-4lo, and allow you to keep your cable speedo. I’ve used it on 3 swaps, and getting ready to do the 4th. Haven’t had the first issue with any of them, installed correctly. Holler if you have other questions, I have a fairly complete parts list for squarebody LS swaps.

Edit- when you say Ls1 do you mean an actual 5.7L LS1 or a first gen 5.3 truck motor?
Click to expand...
It is an actual 5.7L LS1 I believe.
 
For the fuel tank just buy a TBI tank and sending unit from a 1987 K5 Blazer. Then swap the pump to a walbro, I stock the pump you need.

I sell stuff for EFI and other performance goods, I can help if you like. Are you reusing the factory computer or going aftermarket?

Some vendors here may sell LS swap motor mounts, like DIY4X, Hogback Fab, ORD, etc.

Long tube headers will really wake up the engine compared to manifolds, but they are not for everyone.
 
Does anyone have any pictures of an installed Transfer case in 85-86 blazer. I took mine out and wanted to see a couple of pics of how it looks installed before I put it back in. Should have taken pictures myself.

Thanks,
 
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