The Stovebolt Site Forums The Shop Area The HiPo Shop 1952 3600 motor and possible frame swap

Hi, I have a 1952 3600 that I'm looking to LS swap and I know it isn't the easiest choice initially, but I know it can be done. So in looking for an engine I started to consider what else I could use from a donor vehicle, maybe even do a whole frame swap? I've been looking at a lot of 00s suburban, silverado, avalanche, Sierras... anything with an LS in it. Does anyone know if any of these frames would work for my project? Also, any guidance or advice on the engine swap or any part of the project would be a lot of help.


I plan on owning this truck for the next 50+ years and then passing it on so time and money are a little flexible, but I still wanna save as much of both as I can.


I bought the truck as not running, but it had most of what it needed. I replaced the gas tank, fuel lines, and fuel pump and I got to drive to the end of the street before something maybe came loose because it won't start now. I wanted to do an engine swap in the future, but I think I'll do it sooner than I thought, because the motor currently needs a lot of time put into it that could be put towards something with a little more power.

Hey there. Moved your post over to HiPo. Much better spot for your questions.

Welcome to the madness. A frame swap is a much larger effort than an engine swap. Whether it is worth it or not depends a lot on your long term plans.

You mention that you want to keep it and pass it on, but what is your use case for it? Hauling? Racing? Car shows? Commuter?

What other upgrades are you planning to do? Power brakes/steering? Disk brakes? Overdrive transmission?

I don't want to overwhelm you with questions, but having at least a hazy image of your final goal is needed to evaluate what the best initial steps are.

Yeah for sure! I want to maybe pull a couple of horses with it maybe even 4, but thats the most id want out of it. I basically just want a silverado that looks like a 52 3600. Not expecting to go too fast or anything like that, mostly a nice commuter and some light to medium hauling.

What do you estimate your max trailer weight would be?

I'm not exactly sure, I don't know too much about towing and would be willing to compromise on the towing part if that's unrealistic for my set up. 4 horses was just the upper limit of what I might ever need.

As Fibonachu said a frame swap is a much bigger deal than a driveline swap. I am doing a '50 3600 that will be a SBC (Gen 1 not LS) with an NV3500 5 speed manual and a 4.10 Chevy 14 bolt rear axle. My goal is to basically have a 1950 looking truck with a more modern (but not current computerized technology) drivetrain. I changed to disk brakes up front but retaining the drum brakes on the rear. I am keeping the original leaf spring suspension.

There are some other projects you will find here that have done frame swaps, the most common being from an S10. Most current frames are too wide unless you want to stretch things side to side (a bigger challenge).

There are a fair number of LS swaps that you should be able to find information on here with the balance of the drivetrain a mix depending on what was desired.

The rear of the 3600 frame is narrow compared to the 3100 frame so that impacts what works for under bed fuel tanks, rear axles conversions, etc.

A 4 horse trailer is going to need a bigger truck than your 3600 to haul (and stop) it safely, regardless of what frame it happens to be on. That's dual rear wheel, 10,000 pound GVW territory, probably with a gooseneck hitch in the bed of the truck. The current 3600 frame and suspension will probably handle a 2 horse bumper pull rig with a good set of trailer brakes, with a V8 conversion and some brake upgrades to the truck. I'd suggest using something like a mid-1970s Cadillac 472 or 500 engine and a Turbo 400 transmission, but I'm an old geezer who's stuck in the late 20th. Century! Some of the young sprouts will be onboard with some variety of LS engine, an overdrive trans, and half a dozen computers. Have fun!
Jerry

Is your 3600 a flatbed? Doing some initial looking, a 4 horse trailer is 7k-9k lbs.

An advantage to doing a frame swap is that it has a matched set of engine, brake, wheelbase, etc with a properly calculated towing capacity.

Having a flatbed makes it easier to hide a change in wheelbase.

Thanks for all the advice, I don't have a bed right now and a 2 horse set up is fine with me. So for the frame swap option should I get to measuring and looking for something similarly sized? E-zchassisswap.com has a kit that includes trucks up to 03 for a 49-55 chevy/gmc. Maybe something in that range will fit me?

Most modern frames will have a wider stance than the 1950s stovebolts. Tires hanging out of the fender openings will be a dead giveaway that something's not kosher about the chassis. Some people choose to fit big bolt front sheet metal to frame swap jobs, as those fenders and other parts are slightly wider than the pickups and 1 ton front sheet metal. A flatbed will also be a lot more forgiving if you go that route, particularly if you choose to use a more modern rear axle with a wider footprint. The cabs are all the same, more or less, even up through the 1 1/2 and 2 ton models.
Jerry

As I recall, the ez-chassis swap setups for the 49-55.1 trucks sit on an S10 frame. If so, your towing capacity will be less than half what you are looking for.

Looking through the Ez Chassis Swap info, their kits are for S10s. Those are technically rated for 6k lbs towing, but I sure would not try that.

Are you wanting to use it primarily for towing horses? Or occasionally?

If that is the primary use, you are probably better off with a newer diesel. That is the most efficient way to haul heavy loads.

If you are planning to drive it without the trailer most of the time, a 6.0/4L80e into the existing frame with a cam, a good tune, and good trailer brakes would be my recommendation. That would give you the power the pull it (with bad mileage) and the stopping power to stop it.

Yeah, I don't expect to be towing much. I would like to occasionally tow 2 horses though. I'm not opposed to keeping the original chassis, but I think I've read somewhere that suspension has to be updated to fit an LS motor and some other work. I'm just considering what I should look for as a donor and what I can salvage from it.

Your biggest issue with a frame swap is going going to be the track width like Hot Rod Lincoln mentioned above. Pretty much everything with "truck" weight capacities post 1955.2 are quite a bit wider and the tires will stick out past the fenders. It is a look, but not one that appeals to me. Being illegal is also a pretty significant downside.

The weight of an LS/4L80e will be a bit less than your current drivetrain. I don't know enough about the front suspension setup on the AD trucks to say if there is an easy fix for that. Maybe someone with more eperience on them can chime in.

In terms of mounting the engine, I you would run into issues with the frame width since the earlier trucks were narrower. You can work around that by raising the engine (the LS is shorted than the I6), but then you run into clearance issues with the transmission tunnel.

All of this is solveable with enough time and effort, but it is a non-trivial amount of custom work. Generally speaking I am all in favor of a good swap, but you need an idea of what you are getting into before you commit.

On the subject of picking a donor, the the 1999-2002 engines use a 512k ECU and (almost all) have a cable throttle and mechanical fan. The 2003-2006 use a 1mb ECU and (almost all) have an electronic throttle and electric fan. There are other differences in the wiring, with the later engines having more sensors (such as the oil pressure) wired into the ECU to enable additional diagnostics. Once you get into 2007+ engines, you get the Displacement on Demand and Active Fuel Management versions and lose a lot of the reliability.

I personally like the 03-06 versions best. The electronic throttle pedal is easier to retrofit into random place, the electric fans are lower profile than the mechanical ones, cruise control is free (built into the electronic throttle system), and the electronic throttle works better than the IAC for getting a larger cam to idle smoothly.

Taking all of the above into consideration, my suggestion to use the original chassis and a Cadillac/TH400 powertrain sounds better to me all the time. I towed an 18 foot 3 axle trailer loaded with all our worldly possessions from California to Tennessee back in 1980 with a 72 Cadillac Fleetwood Brougham, with a 472/400 powertrain. My wife drove our 59 Suburban with a 307/SM420 and a Dana type 60 rear axle, and towed a Datsun station wagon. Gross weight of the car/trailer combo was 13,700 pounds. The rig never missed a beat, but it only got 5 MPG for a 3K+ mile trip! The Burb got 10 MPG. Drive 100 miles and fill up with gas- - - - -"Rinse and repeat!"
Jerry

If a caddy/TH400 engine will fit down between the frame rails and under the cab, an LS will as well. The 4L80e is longer than a TH400, but the same height.

On the ill-fated trip from Alaska to here last summer, the 6.0 4L65e in our Escalade got 10.2 mpg pulling an 8100lb trailer (somewhat over the bumper tow rating). In my mind, that is bad mileage.

At the end of the day, go with what you like. If you want a fuel injected truck, the LS is the easiest way to do that. If you want to stick with a carb, the Caddilac engine is a fine choice.

The 6.0 and 4L80 combo is an excellent choice. I have both a '02 Silverado and a '03 Sierra sharing that drivetrain. If you're sure about switching frames, I'd check out and see what's available from those that specialize in that area (Morrison, Fatman, TCI etc).

John

Those Caddy engines are actually only slightly heavier than a Chevy small block, and not a whole lot bigger dimensionally. GM hit a home run with that design, and it's a shame it got paired up with a lead sled body/chassis combination. That old Fleetwood got retired at 300K+ miles, not because the engine or trans wore out, but because the front end got so bad it was eating tires like popcorn. It's still out behind the barn, waiting for the drivetrain to get transplanted into some kind of future project.
Jerry

Cruising on the highway at 75 mph without towing a trailer or being packed to the gills, that Cadillac 472/500 can easily get 14-18 mpg. Around town, 10-12 mpg is more like it.

Another vote for the 472/500 is that there are lots of performance options available for it similar to the stuff you can do with a SBC.

They'll even sell you a complete 500ci engine built to your performance needs. One of their categories is Street Rod/Classic Truck

https://cad500parts.com/

My EXTREMELY low mileage 500 cubic inch 75 Caddy engine got snagged by a metal buzzard who got low on beer money and found it sitting in the back of my barn one day. A couple of other engines followed him home at the same time. It was a couple of months before I knew they were gone, and he was not available by then to suffer the consequences of his thievery- - - -but I've got a really long memory! The 472 is still sitting in the old Fleetwood, and the TH400 trans from the 75 Caddy is still around- - - -securely behind a locked door now!
Jerry

That's too bad about the engines getting stolen. I am still leaning towards the LS, FI is nice and since they're everywhere. I can see myself doing a couple more engine swaps in the future and I think if all of my projects are the same engine it will be a little easier in the long run. For now I'll keep the same chassis, I was just thinking it might be easier to set the cab on a 2000s suburban chassis and call it good, but maybe it isn't all that simple.

So now I think the question is what motor should I be looking for? The 5.3 should be plenty of power right? I plan on most of my driving being just commuting and if I do tow something the limiting factor would be the weight and stopping power if the truck? I think I'll likely find a running vehicle with a 5.3 and take its drive train, but I've heard that after about 07 they have AFM. Are there other things to avoid? I'd also be willing to get a 6.0, but if power isn't my limiting factor for towing and I don't expect it to be fast, I would like to get a more efficient 5.3.

A 5.3 would be fine for commuting, but you would be pushing it pretty hard for that kind of towing.

For reference, a 5.3 or 6.0 from a suburban/1500 will have a 4L60e/4L65e behind it. Going up to a 2500 donor would get you the 6.0 and a 4L80e that will stand up to towing loads much better. A 6.0 with lean cruise enabled will get comparable mileage to a 5.3 for commuting while keeping the higher power available for towing.

As far as whether the 5.3 would do the job if you kept it slow, I would say that depends on your gearing, tire size, and definition of slow.

The 2007+ have the AFM/DOD system that is prone to rampant failure. If you are planning to open it up begore the swap, you could remove that system and put a standard cam/lifter set in it. If you want to just make the swap and be done, I would avoid that version.

The 07+ engines also use a new/different ECU that is much more prone to failure than the 00-06 version. It can be converted or you could put an aftermarket engine control on it, but this sounds like a project that you want to do faster/simpler/cheaper than that.

As a point of comparision, I put a 4.8 from a 2000 1500 in an 84 half-ton truck with a 3.55 rear end and 27.5" tall tires. I rebuilt the 4L60e with upgraded clutches and an 1800rpm stall converter. Commuting to work at 70mph, I get between 19.2 and 20.1mpg consistently. Going cross-country at 85mph, I get ~17mpg. If I pull more than about 2500lbs, the torque converter basically never locks up. Above about 4000lbs and it won't hold overdrive on the highway.

That said, older trucks didn't *have* overdrive, so that isn't bad compared to them. But my Yukon with the 6.0 4L65e will hold lockup up to about 4000lbs and use all of the gears up to its rated 6500lb towing capacity. In trade, it gets ~17mpg both commuting and going cross-country at higher speeds.

For my specific purposes, I am happy with the decision to put the 4.8 in because it was dirt cheap, dead reliable, and gets better mileage in all use cases than the original engine did. For 98% of the time, I am towing less than 3000lbs with it and the slightly higher mileage is worth it.

Another thing to consider is that I have it set up fully legal with both cats, egr, evap, etc for an 84. If you are putting it in a truck from the 50s, that extra equipment is not required and you can squeeze some more lean cruise out and have more tuning flexibility.

That's a lot of good info, as far as fitment goes would the 5.3 and trans fit just the same as a 6.0 with the 4l80? And what kind of chassis reinforcement am I looking at? I think I've read the steering box needs moved, what about cutting a tunnel and motor mounts? Also I don't think I mentioned, but I would prefer it to be auto so the rest of the family can drive it too.

The exterior dimensions of the 5.3 and the 6.0 are identical. The 4L80e doesn't taper as much as the 4L60e, so it will be taller under the cab.

As far as motor/transmission mounts, I would recommend something like this. What you have to do as far as firewall/tunnel modifications will depend on where you position the engine.

You want to make sure that the output shaft of the transmission is angled down the same amount as the rear diff is angled up to minimize driveshaft vibration and maximize ujoint life.

Ok I just drove the donor, a 2002 Yukon Denali with a 6.0, home today! So it wouldn't be easiest to just pull the shell off the Denali and put the cab of my 3600 in its place right?

Cool, looking forward to following your progress.

John

You can pull the body off the Denali and swap the cab onto it.

A few observations:

The Denali has a 116" wheelbase (or 130" if it is a Denali XL). That is a fair bit different than the 125.25 of the 3600. If you end up with a flatbed, that difference can disappear into the noise. If you want to put a traditional bed on it, you will have to either move the fenders or adjust the frame length.

The Denali is 78" wide compared to the ~73" width of the 3600. That will manifest itself in the stock wheels sticking out of the fenders. You can get offset rims that will tuck them in some, but 2.5" per side is a lot.

The fuel fill port on the Denali is on the back, driver side. You will need to come up with a support for it or routing to the stock fill port on the cab.

The 3600 master cylinder is under the floor, where the Denali setup expects it to be on the firewall. The easist solution is probably to get a firewall pedal mount and convert the cab using that.

The stock 3600 steering column isn't compatible with the Denali box and the denali column won't fit/mount in the cab. Some kind of custom mount/shenanigans will be needed to hook up the steering. I have read good things about using 80s S10 columns for that conversion on 3100s. That might also work for you. Alternatively Speedway sells a well priced universal column with your choice of ignition location and shifter location.

Electrically, you can separate the cab and the chassis at the bail connectors on the fuse block, then hook your 3600 wiring into it there. That is pretty straightforward to do.

As far as gauges go, the oil pressure sensor on the denali goes straight to the gauge, so you could replace the sender with your original one. There is a spare coolant temp plug on the passenger, rear head that you can put your origonal temp sender into. The easiest thing to do for the speedo is get a digital->mechanical converter to run your stock speedo.

Is the Denali 2WD or AWD? The AWD ones have a controller that will need to be transplanted with the engine harness. I don't know offhand if it uses any inputs from the BCM or not.

When putting TF cab on a GMT800 frame, the inner fenders need trimmed for the shock mounts and the bottom/back of the cab needs trimmed to clear the wider frame. The AD trucks are a bit narrower so you will probably have to do something similar.

The ABS and Traction Contol biasing is different between the truck and suv platforms, so you might consider getting your ECBM reflashed to the truck variant.

If you want the cruise control to work, you need a later model dual pole/dual throw brake switch.

The heater core in the 3600 is going to be a lower pressure rating than the LS cap. The easiest answer there is to replace the heater core with a modern one that can handle the higher pressures, but I don't know offhand what is available off the shelf.

------------

Bottom line: Having the swapped frame gets you a lot of benefits in modern technology, parts availability, etc. It is a non-trivial effort though.

As long as you go into it with your eyes open, have fun and we are here to help you out along the way.

Thanks, thats great! I'll do some more research and see what the best option is

read the entire thread and only question I can think of in benefits of frame swap (now we know what the doner is) is why not just use the AD big truck front clip, fenders and hood. to make up the width difference? seems there has been discussion of that on other posts when building restomods with the shorter rake of the hood and fender width being a plus. what is the overall width difference between big truck/small truck AD?

Going through the dimensions in the 1952 Vehicle Information Kit, it doesn't look like there is one big enough to fit the GMT800 donor width.

Once you get to the 4000 series, they are just shy of 75" across the fenders.

For the Task Force trucks, the big bolt body works nicely on the newer frame because they are a fair bit wider than the AD trucks.

So I am working towards getting the yukon body off of its chassis. Everything's going fine so far, almost have all the wring ready to push through the fire wall. Would it be a good idea to put the yukon motor on an s10 chassis and the 52 chevy cab on top?

The S10 frame will have minimal weight carrying/towing capacity.

What wiring are you wanting to push through the firewall? You should be able to unhook the body wiring at the bottom of the engine compartment fuse panel. The bail connectors bolt in, just unthread them and the connectors will come out.

Oh, well whats done is done haha I should have spent a little more time looking. Ok, at this time I'm thinking just setting the chevy cab on the yukon chassis is the way to go and I'll live with the wheels hanging out a couple inches or maybe find rims to offset it?

Pretty soon there won't be any "original" stovebolts at all left!

www.youtube.com/watch?v=NVIbCvfkO3E

LOL!
Jerry

Progress photo, it took about 5 minutes to just unplug it at the fuse box vs 5 hours in the cab haha

Almost ready to lift the cab off, I just need 3 more jacks

I'm looking forward to see how this goes. Could you start a thread in the project journals section? I put my '47 3800 panel truck on a '88 K2500 frame. The tires do not stick out past the fenders. I maintained the stock height. I thought about using a suburban frame, but it was not flat enough, and too short. The truck frame does dip down under the cab, but no modifications to the bed were needed. I used the wiring harness from under the dash as well as the one on the engine, you might need to to connect to the ECM.

As you may or may not know, the Project Journal forum is now by invitation only and the uniqueness of the build, plus continued updates merits this special recognition.

The DITY Gallery is the forum to start a journal. The DITY gallery is where we look for possible submitters. If your posts are interesting and regular, you just may be invited to participate in the Project Journal forum.

Good luck with your build, I’ll be following!