91 Pickup LS Swap

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91 Pickup LS Swap

Postby Honestbroker » Sun Feb 07, 2021 3:49 pm

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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Re: 91 Pickup LS Swap

Postby mudoilngears » Wed Feb 10, 2021 8:11 pm

Cool project!
Image
1998 Rodeo LS 4x4 4JB1-TC Diesel Swap, Moog CC247 coils, more mods to come!

SOLD- :( 1990 Isuzu Amigo 4X4 4ZE1 engine. Front Aussie Locker, HD Sway Away T-bars,Smittybilt XRC8 winch.
Build in progress...
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Re: 91 Pickup LS Swap

Postby Honestbroker » Wed Feb 10, 2021 8:35 pm

Thanks.
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Re: 91 Pickup LS Swap

Postby freddyfreeloader » Wed Feb 10, 2021 9:19 pm

this is sweet!
I wish you best of luck, please keep us posted on the progress.
That tranny is an automatic version?
What if you want a manual tranny? What model works then?
Also, what rear axle? Can the original handle the extra power?
I'm also curious about doing an LS swap on my truck.
The original engine is too weak. I use this truck for work so I pound on the miles.
The LS is simple technology, very reliable and strong.
I think it is probably a better option than a lexus 1UZ.
no timing belts!! changing them every 90k miles doesn't look like a pleasant experience.

As long as I go easy on the throttle the gas mileage is almost the same as the original 2.3 liter!!

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Re: 91 Pickup LS Swap

Postby Honestbroker » Thu Feb 11, 2021 12:03 am

The tranny is a 4L60e (auto). I went that way mostly for simplicity’s sake. The original was manual, but to put in a manual meant increased costs and I have a target budget I’m trying to stick with. A number of folks have said that the rear end and drive shaft will probably handle the extra power as long as I don’t go out drag racing all the time. Time will tell. I’m waiting for the transmission so I can bolt everything up and begin fitting it all in the truck. I read somewhere that the drive shaft may only need a trimming of the yoke. Again, once I know, I’ll post it here.
Thanks.
- Mike
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Re: 91 Pickup LS Swap

Postby Tentin » Thu Feb 11, 2021 12:13 am

Reminds me of one I saw on craigslist recently which I thought was incredibly overpriced but I guess it sold. He was using the stock rear end presumably with no issues. Maybe you could track him down and get some info out of him

https://dailyturismo.com/sleeper-cab-19 ... ickup-ls1/
1995 Isuzu Pickup 4WD aka Suzie Q. 3" lift, 32" A/T's
1998 Isuzu Amigo 4WD aka Smeagol The Amigo. 2" Lift, 31" A/T's

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Re: 91 Pickup LS Swap

Postby Honestbroker » Thu Feb 11, 2021 12:26 pm

Thanks. Yes, this is a very nice job and I wish I could find out how to contact this guy. I have a ton of questions. I'll keep looking for contact info. Appreciate the input.
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Re: 91 Pickup LS Swap

Postby szac » Thu Feb 11, 2021 5:42 pm

Honestbroker wrote:Thanks. Yes, this is a very nice job and I wish I could find out how to contact this guy. I have a ton of questions. I'll keep looking for contact info. Appreciate the input.


Here he is with the build on this site. Maybe you could reach him?
https://grassrootsmotorsports.com/forum ... 545/page1/
2000 Trooper 3.5 4WD 5sp
1989 Pickup 2.6 4WD 5sp
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Re: 91 Pickup LS Swap

Postby Honestbroker » Thu Feb 11, 2021 6:35 pm

Thanks a ton. I’ve logged in and sent a note to carwhisperer. Hopefully I’ll get an answer soon. I appreciate your help here.
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Re: 91 Pickup LS Swap

Postby geoffinbc » Thu Feb 11, 2021 8:06 pm

The 12 Bolt Isuzu axle will take the power no problem. It is bigger than a Dana 44
1990 Trooper, 3.2L (3.1L .040 over) Pushrod V6, 5 speed manual. 33X10.50X15 BFG M/T KM2's. 3" OME Lift. Cowl Induction Intake. ARB Lockers front and rear. HD Tierods.
Off the road for an overhaul right now.

Big Bore Intake Kits & Greasable Shackles Here
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Re: 91 Pickup LS Swap

Postby Honestbroker » Thu Feb 11, 2021 8:10 pm

Thanks. Good to know. I appreciate the info and your help.
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Re: 91 Pickup LS Swap

Postby Honestbroker » Sat Feb 20, 2021 6:29 pm

Update: I just finished a trial fit with the motor and transmission. The main objective was to determine engine mount placement and alignment with the tunnel. At first, I tried to put everything together and drop it in from the front. I couldn’t make it work due to interference with the firewall. We backed everything out and disconnected the transmission from the motor. We slid the transmission under the truck and positioned it close to where the rear of the engine would meet it. By the way, I did remove the transmission mount plate that was held in with four bolts in order to slide the tail of the transmission over the frame cross member. Worked like a champ. Anyway, we then brought the motor back in and positioned it until we could wrestle the transmission onto the guide pins. Once we had that, we put bolts in and lined everything up. I think I’m set to go get a couple of pieces or 3/8” plate to do some final fabrication for the frame mounts. The pictures don’t show it, but I’m planning to do as recommended and place the clamshells with the ICT adapters on the block with the ls mounts going to the frame mount location. Anyway, here are some photos. Comments are always welcome.
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Re: 91 Pickup LS Swap

Postby Honestbroker » Fri Mar 12, 2021 1:32 pm

Time for another update. I finally wound up using 1/2" plates (went to a local weld shop and was able to get 2 - 5" x 7" x 1/2" and 2 - 5" x 7" x 3/8" pieces for $20. I recommend doing that instead of a metal sales shop) on each side frame mounts to adapt the swap mounts to existing original mount position. I placed studs into the plates and welded them flush, aligned with the original holes for the stock mounts. I then drilled and tapped four holes on each plate to accommodate the Trans-Dapt swap adapter mounts (pictures should show more clearly). I used ICT Billet SBC to LS motor mount adapter plates, reversed the Trans-Dapt engine mounts to attach to the ICT plates and put the Trans-dapt adapter plates on the 1/2" plates I built for the frame mounts. I expect there may be a much simpler way to do this, but it's what I did. I did a trial fit test and then removed everything for a paint job. I just put everything back together and am waiting for the transmission (should be ready any day now).
Anyway, here are some photos (more available if anyone is interested). Questions, comments, and recommendations are welcome.
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Re: 91 Pickup LS Swap

Postby freddyfreeloader » Fri Mar 12, 2021 7:16 pm

congrats on the work, very nice and clean.
this should last a long time! that is the idea, simple and reliable!!!

:D
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Re: 91 Pickup LS Swap

Postby Honestbroker » Fri Mar 12, 2021 11:36 pm

Thanks. I appreciate your comments.
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Re: 91 Pickup LS Swap

Postby Rangerguy0469 » Thu Mar 18, 2021 4:55 pm

This is really awesome. Just purchased an LS2 for my 89. Really am happy to see someone doing this swap. My dad and I are getting everything together and going to start the project in May or June.
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Re: 91 Pickup LS Swap

Postby Honestbroker » Fri Mar 19, 2021 12:47 pm

Thanks for your comments. You've got a nice looking truck there. I'm enclosing a photo of the oil pan as it hangs below the cross member. I think it's too low for normal driving in my truck use unless I really jack up the truck. Your truck looks pretty slammed and I think you'll want to deal with this from the start and the stock LS2 oil pan probably wouldn't work for crossmember clearance. I'm quite sure I'm going with a Holley 302-1 LS Swap retro fit oil pan. It's 2 1/2" shorter in the sump (better ground clearance) and about 1" - 2" further aft on the forward end of the sump (better crossmember clearance fore and aft). It's pricey, but I think it's needed. If you or any of your friends have another solution, please share. For now, I'm searching for one of these used or any other ideas folks out there may have.
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Re: 91 Pickup LS Swap

Postby Rangerguy0469 » Fri Mar 19, 2021 12:53 pm

Thank you. Yes that is helpful. The motor I have now has a front sump on it anyway so I will look into that Holly pan definitely. I know it will be a lot of work but I’m excited to start this journey.
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Re: 91 Pickup LS Swap

Postby Honestbroker » Fri Mar 19, 2021 2:57 pm

Just curious, you said your LS2 had a forward sump. Was it from a GTO?
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Re: 91 Pickup LS Swap

Postby Rangerguy0469 » Fri Mar 19, 2021 3:46 pm

Sorry it is rear sump. Came out of a 06 corvette!
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Re: 91 Pickup LS Swap

Postby Honestbroker » Fri Mar 19, 2021 4:39 pm

See next post.
Last edited by Honestbroker on Fri Mar 19, 2021 4:43 pm, edited 1 time in total.
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Re: 91 Pickup LS Swap

Postby Honestbroker » Fri Mar 19, 2021 4:42 pm

No problem. By the way, there's a site, Super Shops, that has a Holley 302-1 clone for $259.95 (Black - part SS11003) and $239.95 (Unpainted - part SS11002 I think). Shipping is free/included. They're available on Amazon too, same vendor. Most sites list the Holley for ~$375.95.
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Re: 91 Pickup LS Swap

Postby Rangerguy0469 » Fri Mar 19, 2021 4:55 pm

Do you have more pictures of the motor sitting in place. My dad is wanting all the info we can get.
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Re: 91 Pickup LS Swap

Postby Honestbroker » Fri Mar 19, 2021 5:22 pm

I still haven't finished all the fitting, but the mounts are pretty much set. Here are some more pics.
Also, I may be able to help you with some fuel system ideas.
Early fitting.JPG

More motor mount detail - passenger side looking aft.jpg

Passenger view looking aft.JPG
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Re: 91 Pickup LS Swap

Postby Rangerguy0469 » Fri Mar 26, 2021 3:48 pm

If you don’t mind me asking who did your transmission and what all are you having done to it?
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