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91 Pickup LS Swap

7K views 30 replies 7 participants last post by  Honestbroker 
#1 ·
I'm new to the forum and thought I'd share some of the experiences I'm having with my project. I have a 91 base truck that I've had since new. It's been in my son's garage since the motor failed for the second time back in 2006. The truck is in very good shape body-wise with a very clean interior. Anyway, in late November 2020, I decided to pull the old engine and build a project LS swap truck. I'd read a ton of posts and spoken (chatted via text mostly) with a couple of folks who had done this with a couple of trucks. So, although I thought I'd stay with a manual transmission, T56 or the like, but decided on a 4L60e after speaking with a number of rod builders and seeing, at least from posts, that it'd fit with minimal to no tunnel "hammer mods."
So far I have a 5.3 that's been built for me. I just didn't have the space or machine tools. The builder ensures that it'll be putting out 375-400 hp, more than enough for the little truck. The motor has been sitting in my shop (son's garage) for several weeks now while I have been sorting out fuel system mods and some bushing replacements. The transmission is being built, but it's in queue. I tried a first fit try and see that the stock frame pads are going to need mods (I knew that). I was loaned an aluminum LS bare block for a fit try, but it just doesn't give me all the dimensions I need to make sure things fit.
First fit showed me that I had the motor setting too low as the front of the oil pan was resting on the steering center link. After checking with some other successful swappers, I was assured that all I'd need to do is space the motor up in the mounts. Other than that, the motor looks like it'll fit, although it's going to be tight (I've already read that several times too).
I need some help in many ways still. Headers seem to be the only way I'll be able to go. Recommendations? Also, exhaust routing will be a concern. Has anyone gone with a dual exhaust? How about single? Pros, cons?
AC and heater plumbing. Thoughts? Initially it looks like the heater inlet and outlet is blocked at the firewall. Ideas?
One more thing, I used the original fuel tank with some mods. I'm using the original 5/16 fuel feed as a return and have modified the aft vent fixture (top of tank) with a new fuel draw (6AN) to a pre-filter and then to a Walbro 255 LPH external fuel pump.
Lots for now. Here're some photos of the truck and, yes, we did cut the top of the front radiator frame. Comments and recommendations are welcome.
 

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#27 ·
I thought this had posted before. Trying again.

4L60e Core, 4L60e Core, Master overhaul kit w/ alto a-pak clutch kit, bushing
kit, HD wide band, smartshell reaction shell, 1-2 accumulator piston, 3-4
accumulator piston, EPC solenoid, 1-2 shift solenoid, 2-3 shift solenoid, 29
element HD fwd clutch sprag, harness connector bracket, input speed sensor,
fwd. accumulator piston, transgo reprogramming kit, TSI 2400 stall converter,
filter, dipstick w/ tube,and flexplate.
 
#29 ·
Good work this weekend. Got the motor and transmission into the truck as a single assembled unit. There's still some more to do to accommodate the intake manifold. I've had to do a little bit of hammer mod work, and it's still tighter than I'd like.
I'm stuck trying to figure out what exhaust headers/manifold Will be the closest fit. Still need a floor shifter; there seems to be plenty of room between the transmission and tunnel. Still need to place the tail mount. Still need to figure out a parking brake workaround. Still need to find a 96 Rodeo instrument cluster.
Advice and recommendations are always welcome, as are any questions.
 

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#30 · (Edited by Moderator)
Another update:

Got the motor and transmission mounted. I bought a stock transmission mount (see photo) and modified, slightly, the original mounting plate. Once all that was done, the engine and transmission were assembled (pinion angle looks great) as it will be from here on out... except that I'll need to pull everything out one more time to facilitate some fuel, brake, and transmission cooling lines' installs.

Still need headers, heater line setup, 97 Rodeo instrument cluster, radiator, and probably something else... like a wiring harness. I just ordered TCI FAST-GATE Shifter (616541). Should be simple and reliable.

Here are a couple of pics. As ever, comments and recommendations are welcome.
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#31 ·
It's been a while. Unfortunately, I'm often a one man show and moving the engine/transmission in and out (every time I think I've got it all figured out, I find out I don't) on numerous occasions holds me up. I've ordered and received a very nice harness from a factory in China, but still haven't attacked hooking that up. I do believe I have the engine/transmission resolved for now. I bought some inexpensive headers that fit (with some minor firewall hammer mods on the passenger side). The parking brake is even going to be okay. I'll have to do a very minor pull-off near the driver side headers, but don't expect a big challenge there.
So, although there're plenty of different obstacles to getting this done "just right," I'm focusing specifically on the drivetrain for now. Water pump, fuel lines, radiator, alternator, harness hook-up, are all on the list for sooner than later accomplishment. I've cleaned out the intake manifold. That was a mess. I'm going to plumb in some sort of catch can or filter for the PCV gasses to pass through before going into the manifold. I don't know why GM did things the way they did.
The shifter is pretty much ready. I have some electrical connections to sort out, but I'm confident they are just things to do and not so much things to figure out. And, mosquito season is in full swing here.
I'll post some more photos soon.
 
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