Explain to me like I'm 5. How easy is an LS swap?

[Drunkcanuk]

This is officially the longest message I’ve ever personally seen on this forum

It needs to be a sticky of it's own!

 

[movietvet]

What are you even on about? I didn't disregard you, I quite literally gave you what you asked for, I just didn't do it at 10pm on a Monday. My post isn't about an inexpensive towing rig, it's about how feasible dropping an LS into this chassis is. I understand I'm going to be out thousands of dollars. That's the hobby after all.

The rear gear isn't ideal but it gets the job done for now, eventually I will change it. What good is 4.10 if the 700r4 explodes or the 350 drops a cylinder? An LS AND 4.10 gearing is possible. Those are not impossible things to combine. Regardless, this truck does a great job towing anyway in it's current condition, the question has and always will be for how long? In the year I've had it, it makes monthly trips to the metal yard with 2k in bed, has towed 8k in the form of a 67 Caprice and 25ft trailer from Chicago to Saint Louis getting 13 MPG @ 55mph, towed a Miata from the hills of Branson MO, did 16 hours round trip to Krakow Wisconsin to pick up the fun car. It did and does great, but for how much longer?

The 700r4 is a good transmission, I have never doubted that, I never said anything to even imply I didn't think that. MY particular 700r4 isn't very good, if I were to drop the pan I would probably find 17lbs of clutch material on the bottom. I would keep it and rebuild it, but if I'm going for a modern engine wouldn't it make sense to put a modern transmission in it? You wouldn't put a 2016 engine in your tow truck paired to a powerglide because it's "a good transmission."

Whether or not the 350 is stems or rings doesn't matter to me because I don't plan on keeping it. "The 350 and 700r4 are doing fine enough" doesn't mean they're factory fresh, it means I turn the key and it still stumbles to life and starts driving with a smoke and oil trail. I don't understand what the resistance is to wanting to plan ahead and have some stuff ready so that I can drop a fresh engine and trans in maybe before the truck leaves me stranded in the middle of nowhere while towing something. "Maintenance pays & breakdowns cost" and there sure as hell hasn't been any maintenance done to this truck in it's life and I'd bet it's probably too late to start now so I think I'm just left with breakdowns.

Just because it's numbers matching doesn't make it good.

I based all my comments off of your original post where you said the engine and transmission were doing fine enough and you would wait till they "let go" and then look at an LS and transmission swap. You complained about the towing up hills. I stated to do the gears and asked what gear you have and then guessed at a gear ratio I had never heard of.
I never asked for or expected a late night response and you did respond back the next morning when you chose to. After I asked about your gear ratio, you still responded to other posts till later in the evening. I did not ask for an immediate response. I just wanted an eventual correct response. If you already had a 3.73 or 4.10 gear ratio, it would all be a moot point.
I lived in KC, Mo. a lot of years and in the shops and had to deal with eastern Mo. people sometimes and the "good enough" responses.

You are correct. This has gone way too far. Exaggerations abound.

 

[Sean Buick 76]

I’ve had lots of LS powered trucks and SUVs and I will say that they want to rev to tow. A 4.10 or even 4.56 gear will work magic for towing. I still say the 99-06 6.0 and a 4.10 gear is the best route.

 

[Leeztruk]

Sorry if I'm late to the party, but thought I'd offer some insight from my LS swap in my '89 truck. Don't go crazy on cam selection. A low lift cam of around .550" or less and short duration (208/214) should give you the torque you need. Choose a better stall convertor (2200-2500) will help the engine with your gears for pulling. Get slider type mounts to position your engine/trans in a position where you can run your stock driveshaft and column shifter. It'll require you to move the stock trans. crossmember back about 2". Stock exhaust manifolds will work, but manifolds from V8 trailblazers/envoys/raniers will fit closer to the engine block (everybody says go trailblazer SS manifolds, but guess what, they're all the same). Most of your truck's engine wiring for the TBI and ECM wiring won't be needed, as LS 's use their own PCM and harness(go aftermarket). These harnesses will have the necessary fusing and relays for your fuel pump and fans. Keep your engine's temp. and oil pressure senders/wiring for your gauges. Pretty much, that's it. I would recommend using a gauge cluster from 92-94 for speedometer compatibility with the PCM. If you can weld, making an exhaust system shouldn't be too complicated

 

[Additivewalnut]

Sorry if I'm late to the party, but thought I'd offer some insight from my LS swap in my '89 truck. Don't go crazy on cam selection. A low lift cam of around .550" or less and short duration (208/214) should give you the torque you need. Choose a better stall convertor (2200-2500) will help the engine with your gears for pulling. Get slider type mounts to position your engine/trans in a position where you can run your stock driveshaft and column shifter. It'll require you to move the stock trans. crossmember back about 2". Stock exhaust manifolds will work, but manifolds from V8 trailblazers/envoys/raniers will fit closer to the engine block (everybody says go trailblazer SS manifolds, but guess what, they're all the same). Most of your truck's engine wiring for the TBI and ECM wiring won't be needed, as LS 's use their own PCM and harness(go aftermarket). These harnesses will have the necessary fusing and relays for your fuel pump and fans. Keep your engine's temp. and oil pressure senders/wiring for your gauges. Pretty much, that's it. I would recommend using a gauge cluster from 92-94 for speedometer compatibility with the PCM. If you can weld, making an exhaust system shouldn't be too complicated

This right here is the kinda stuff I needed. Thank you. I figured it would be this easy, most Chevy stuff is. How complicated does it get to get the power steering pump and AC to go where it used to? I saw on that real long post that there are adapters I can buy. How bad was moving the cross member? Just drill new holes or do some already exist?

 

[Drunkcanuk]

This right here is the kinda stuff I needed. Thank you. I figured it would be this easy, most Chevy stuff is. How complicated does it get to get the power steering pump and AC to go where it used to? I saw on that real long post that there are adapters I can buy. How bad was moving the cross member? Just drill new holes or do some already exist?

You can buy brackets to mount the A/C compressor. Or....there is a thread here about modifying a old pre Vortec 4.3L mount. Check ICT Billet for sure and possibly Dirty Dingo for those brackets.

Power steering lines should bolt right up like I said earlier, UNLESS Hydroboost comes into play. If your donor has it, just get a replacement pump for that year without Hydroboost.

If you are using the sliding engine mounts, you will not have to move your cross member. That only comes into play going from a 700r4/4L60E to a 4L80. And ya, simple as sliding it back and new holes.

 

[Sean Buick 76]

Agreed and yes the dirty dingo swap engine mounts are nice and adjustable.

 

[Leeztruk]

FYI, you don't have to go Dirty Dingo. There are suitable substitutes available at lesser cost, and yes, you can use your power steering stuff. Concerning your crossmember, the 7004r trans. mount is bolted to the main body of the trans. If you go 4L60E or 4L80E, the trans. mount bolts to the tail shaft housing, essentially moving the trans. mounting point a couple of inches farther aft, which, in turn, requires you to move the crossmember rearward.

What I did with my swap, was pull the hood and radiator support so that I could easily move the engine/trans forward/aft to find the best position, leaving the engine sliding mounts loose on the block. Once found, I slid the crossmember to where it needed to be, test fit the driveshaft for proper placement in the trans., then drilled the four new mounting holes in the frame. The shift arm on the 7004R can be transferred onto the newer trans., and you won't need the range switch from the newer trans. The NSS and reverse light switch will be from your steering column switch.

If your '91 is like my '89, you'll have two fuel lines running up to the TBI that are steel braided lines (supply/return). Depending on the year of the new engine, you may have one or two fuel lines. My engine was from '02, so it had supply/return requirements. What I did for my swap was make a fuel line that ran from the filter to the fuel rail, and a line from the filter to the pump. For the return side, I made a line from the rail to the original steel truck line. Because my truck is a daily driver, I wasn't concerned about "pretty" braided stuff, so I used fuel line from Fragola called easy street, along with their fuel line fittings.

For my fuel pump, I used an EP381 pump from ACdelco, but they are getting hard to find. Beware of the knock-off's. You can get those anywhere at really cheap prices. Getting to the fuel sender is not too difficult, and can be done by yourself. All you need is a high lift jack. Undo all the bed bolts on the driver's side, and loosen the passenger side bolts, then lift up on the driver's side of the bed high enough to where you can access the top of the fuel tank. Just so all of this won't scare you, I'm 77 and do my own work