Doing LS Swap - I have no idea what I'm doing!

[EagleChief]

Looking at my crank, it has the part number for the 5.3. I am going to pull a plug this evening and use my new inspection camera to look at the cylinder heads. The camera arrived this morning, so hopefully I'll know something tonight.

I guess, once I determine what I have and assuming it's a 5.3, then I need to check my injectors to see if they are flex fuel type, or the other. The VIN I have from the salvage is definitely a 2003 Tahoe, 5.3L Flex Fuel (L59), 2WD.

I'll report back as soon as I look at the cylinders.

[Thealien]

Most if not all of the flex fuel engines had stainless steel fuel rails.

That doesn’t mean someone couldn’t of changed it.

[EagleChief]

Alright, cylinders are dished, so that, along with the crank, verifies the motor size - 5.3 motor. Ran the TAC module number and it comes up as a '03-'05 part number. Programmer was a little concerned due to some discrepancies of PCM and TAC modules not working together.

Anyway, got that stuff worked out and he's ordered the harness and will get the PCM flashed and ready to go. It's now a waiting game for the harness to come in! Due to supply issues, it could be a couple of days - or, it could be weeks... who knows.

[EagleChief]

Got the call this weekend! My harness arrived at the tuner and he was finishing up my tune. Going to pick it up sometime this week. Hopefully, I can start working on the fuel system install. Want to get the tank mounted and start running the fuel lines. To do that, I'm going to have to cut out a couple of cross-braces - one Z-style crossmember on the frame, and one of the bed braces. I grabbed a piece of 1-1/2" angle from work to use as a mount/support for the tank. I'll fit it onto the frame rails and drill it to bolt into the frame, then I can drill the mounting holes for the tank.

Question - you guys that have done the Wrangler tank, did you use any tank straps to help support the tank? Or, has it been ok to just use the tank flanges to support the tank?

[EagleChief]

I need to cut this brace out to install my gas tank. Any ideas? I started the cut on either side, next to the frame. I'm thinking I'm just going to run along the top - as close as possible. Then, see if I can bend that out of the way and cut the other side of it, and hope that I have enough room.

[Richard]

Originally Posted by EagleChief

Got the call this weekend! My harness arrived at the tuner and he was finishing up my tune. Going to pick it up sometime this week. Hopefully, I can start working on the fuel system install. Want to get the tank mounted and start running the fuel lines. To do that, I'm going to have to cut out a couple of cross-braces - one Z-style crossmember on the frame, and one of the bed braces. I grabbed a piece of 1-1/2" angle from work to use as a mount/support for the tank. I'll fit it onto the frame rails and drill it to bolt into the frame, then I can drill the mounting holes for the tank.

Question - you guys that have done the Wrangler tank, did you use any tank straps to help support the tank? Or, has it been ok to just use the tank flanges to support the tank?

I am not a fan of using flanges on the tank to mount it. I have never seen one mounted that way from the factory. Seems like an easier less costly route. Must be a reason cars do not come that way. My thought is it may be okay for a rigid boxed or tube frame. But for an old frame that flexes and moves a bunch, not a good idea to me. A lot of people do it. Most if not all aftermarket tanks are made with flanges, which is one of the reasons I avoided aftermarket. Just my opinion.
Getting the rivets out can be a pain, but not really any harder than cutting the crossmember.

[EagleChief]

Originally Posted by Richard

I am not a fan of using flanges on the tank to mount it. I have never seen one mounted that way from the factory. Seems like an easier less costly route. Must be a reason cars do not come that way. My thought is it may be okay for a rigid boxed or tube frame. But for an old frame that flexes and moves a bunch, not a good idea to me. A lot of people do it. Most if not all aftermarket tanks are made with flanges, which is one of the reasons I avoided aftermarket. Just my opinion.
Getting the rivets out can be a pain, but not really any harder than cutting the crossmember.

I've been debating making some tank straps, or buying some, to help hold the tank in place. The tank I bought, actually has mounting holes on each corner of the tank flange, so I'm guessing that's what they are for. Now, it is only a 15 gallon tank - which I know will still be heavy when full, but, shouldn't be too bad.

[ls1nova71]

Originally Posted by Richard

I am not a fan of using flanges on the tank to mount it. I have never seen one mounted that way from the factory.

You haven't looked back far enough. Fords, and I'm sure most other manufacturers from about 1932 til around 1948 all had flange mounted tanks. They were notably smaller though so that may be a factor to consider.

Personally I would put straps on a tank in a truck just for the fact that if you put the flange on top of the frame, you wouldn't be able to drop the tank if need be.

[Richard]

Originally Posted by ls1nova71

You haven't looked back far enough. Fords, and I'm sure most other manufacturers from about 1932 til around 1948 all had flange mounted tanks. They were notably smaller though so that may be a factor to consider.

Personally I would put straps on a tank in a truck just for the fact that if you put the flange on top of the frame, you wouldn't be able to drop the tank if need be.

You are correct that I had not looked back that far. Vehicles were still in their infancy back then so I still stand by what I said.

[EagleChief]

Had a little time to cut on the truck a little more last night. I was able to cut some of the bed crossmember out. I still need to get some more of it, but trying to get my Harbor Freight grinder w/ cutoff wheel up under the bed is a tight fit. I may try my Sawzall next to see if it works. I didn't get pictures - will try and get some next time I'm under there.

[EagleChief]

So, it's been quite a while since I've been around, or done anything to the truck. Most of the family came down with Covid, and we lost a family member recently. But, we've been talking about getting after it again - 3-4 months later. Since most of my free time is late at night, I thought I might start trying to lay out the wiring for the motor. I don't where to start. Do I start by mounting the computer somewhere, or do I start hooking stuff up and then mount the computer to where-ever it will reach?

I ended up having a harness made and it's labeled for each connection. It's actually a PSI harness, so I'm not sure how much extra wire is there for the cpu mounting location. I haven't really looked at it too much to try and lay it out.

[jjzepplin]

Sorry for your loss. These are difficult times. Maybe working on the truck will help keep your mind busy. Good to see you back at it.

[A1971Blazer]

Originally Posted by EagleChief

So, it's been quite a while since I've been around, or done anything to the truck. Most of the family came down with Covid, and we lost a family member recently. But, we've been talking about getting after it again - 3-4 months later. Since most of my free time is late at night, I thought I might start trying to lay out the wiring for the motor. I don't where to start. Do I start by mounting the computer somewhere, or do I start hooking stuff up and then mount the computer to where-ever it will reach?

I ended up having a harness made and it's labeled for each connection. It's actually a PSI harness, so I'm not sure how much extra wire is there for the cpu mounting location. I haven't really looked at it too much to try and lay it out.

sorry about the family situation...life happens
as far as the harness is concerned...I would make all the connections, clean up and loom the wires as best you can, then see how much slack you have left going to the PCM and relays
that will determine where to place them...the relay and fuse block should be somewhere accessible for servicing if the need arises....
if you are going to have AC....that limits the amount of room there is behind the dash.
I'm still debating where to put mine on my '67 build , I'm also adding a cruise module...so there's another component to mount....somewhere?

good luck with it...

[LS short box]

On my 68 LS swap I mounted the ECM behind the glove box along with the relays. The fuse block which has CEL light I just screwed it to heater box just low enough so I could see it from the drivers seat. I had to section the paper board glove box liner to make room for the ECM. Still had a pretty decent glove box.

[EagleChief]

I took a look at my harness last night. It does have a grommet on the main harness to allow for entry through the firewall. Maybe there is enough wire there to mount inside the cab? I'm lost at electrical stuff. Luckily, the guy I dealt with labeled every connection and wire on the harness. The harness was made by PSI Conversion. Everything is already covered in wire loom and ready to go. I just have to figure out where to start as far as hooking things up and running the wires.

[biketopia]

Originally Posted by EagleChief

I took a look at my harness last night. It does have a grommet on the main harness to allow for entry through the firewall. Maybe there is enough wire there to mount inside the cab? I'm lost at electrical stuff. Luckily, the guy I dealt with labeled every connection and wire on the harness. The harness was made by PSI Conversion. Everything is already covered in wire loom and ready to go. I just have to figure out where to start as far as hooking things up and running the wires.

Find the area of the harness with the coil and injector connectors. Make sure you have them on the correct sides and then just kind of lay the harness there. then move wires around seeing where they go and just have it kind of where it's going, then make adjustments accordingly.

[Low Elco]

I did the wrangler tank adn built a frame around the flange, then set it on rubber. It's set up so the front rides on top and the back bolts up, so when you pull it, you can jam the front in and swing the back up. Useless pic here- http://67-72chevytrucks.com/vboard/s...=501131&page=6

and here http://67-72chevytrucks.com/vboard/s...=624310&page=7

Ah, here's a better one- http://67-72chevytrucks.com/vboard/s...=624310&page=9

Hope it helps!

[EagleChief]

Originally Posted by Low Elco

I did the wrangler tank adn built a frame around the flange, then set it on rubber. It's set up so the front rides on top and the back bolts up, so when you pull it, you can jam the front in and swing the back up.

I like that idea! I'll probably steal that for my install. My other option was to just bolt the angle I have onto the frame and bolt the tank to that angle. That way if it ever does have to come out, I can just undo the piece of angle and take it out that way.

[clay68c10]

My vote is to put the PCM under the hood if your harness will allow it. GM did it that way, it can handle the heat. The under dash is so tight that it’s hard to find extra room without compromising something else.

[Factory Guy]

For anybody interested this guy JR has a youtube channel where he walks you through how to do a LS swap into a squarebody. From pulling the donor engine at a junkyard and how to rig up the fuel system...

He has all kinds of info.

Here's a link to one of his playlists for a LS swap.

https://www.youtube.com/watch?v=dhVZ...WvfqpMN8YkO9ZY

Scotty Baccus has a great guide on what to do and look out for when doing a LS swap his article is at:

https://tejassteelworks.com/wp-conte...uide-73_87.pdf

[Jdubs71]

Originally Posted by Factory Guy

For anybody interested this guy JR has a youtube channel where he walks you through how to do a LS swap into a squarebody. From pulling the donor engine at a junkyard and how to rig up the fuel system...

He has all kinds of info.

Here's a link to one of his playlists for a LS swap.

https://www.youtube.com/watch?v=dhVZ...WvfqpMN8YkO9ZY

Scotty Baccus has a great guide on what to do and look out for when doing a LS swap his article is at:

https://tejassteelworks.com/wp-conte...uide-73_87.pdf

I loverJR’s content…..”Buy once cry once” LOL
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[EagleChief]

Well, haven't had much to post about lately - or, at all for that matter. I haven't had time to get to the truck with family time. I did spend about an hour in the garage the other night (Friday night) after everyone was asleep.

I put the exhaust manifolds on, the new dipstick tube (Super hard, I know), and started laying out the wire harness. I hooked up all the connections I could easily get to on top of the motor (injectors, alternator, coolant sensor).

I still need to verify some of the locations for the other stuff and try and get to the rear and under the motor to hook up the rest of the connections. Anybody know of a diagram that shows where all the connections are located?

[kev2809]

I don't know if I missed it, but what tank setup are you using?

[Accelo]

Originally Posted by clay68c10

My vote is to put the PCM under the hood if your harness will allow it. GM did it that way, it can handle the heat. The under dash is so tight that it’s hard to find extra room without compromising something else.

Here is a picture of where my ECM ended up. Yes it's connected, the wiring comes up between the fender well and the cab. I plan on painting it black but haven't got around to it yet. Factory holder behind it with a wire bail keeping it in.
My harness was a conversion, not custom, so I had only so much wire to work with.

[biketopia]

Originally Posted by EagleChief

Well, haven't had much to post about lately - or, at all for that matter. I haven't had time to get to the truck with family time. I did spend about an hour in the garage the other night (Friday night) after everyone was asleep.

I put the exhaust manifolds on, the new dipstick tube (Super hard, I know), and started laying out the wire harness. I hooked up all the connections I could easily get to on top of the motor (injectors, alternator, coolant sensor).

I still need to verify some of the locations for the other stuff and try and get to the rear and under the motor to hook up the rest of the connections. Anybody know of a diagram that shows where all the connections are located?

Progress is progress!! I've been trying to get my Camaro fired up so I can get the truck moved in before my first kid is here in June, never enough time! As far as "where all the connections are located?" what all are you looking for, engine sensors, truck connections, others??