What’s the most practical way to swap engines?
 

Ok so I finally found a project truck. 56 GMC stepside. Body is really good considering the age. Floors are unbelievably solid. Cab corners are shot but fixable. Front fenders need some love or just replaced. Interior is wasted but that’s just cosmetic stuff that can wait. For me the first order of business would be a drivetrain and brakes.
I was thinking about a 350 w/700r4 trans. What’s the most practical way to go about it? Is there a certain year of engine/trans I should be looking for? Best mounts and/or crossmember to use? I do not want to change the front suspension. I will eventually put disk brakes on the front. Was thinking PS/PB as well eventually. Other than that i don’t plan on veering too far from stock.
Thanks in advance

Re: What’s the most practical way to swap engines?
 

What engine is currently in the GMC? Ether way your doing a big swap going to auto and power steering.
Are you on a budget? I like to think we all are, if your wanting to go cheap you could buy a doner vehicle and swap all the engine and trans stuff. That could be an LS car or and older TBI or carbed vehical. If wanting all new, I would get with a supplier like CPP and get all the conversion items needed. Power steering box and pump, disk brakes, crossmember. Look at some of the build threads and get some ideas.

What rear end is in the truck? The stock gears if 3.90 or 4.11 should be OK with an OD trans but if 3.38 it may be a little doggish.

Hope this helps. I used a 93 GMC parts truck and swapped the tbi engine and transmission stuff into my 59. Nothing was bolt in as much as I would have liked it to be.

Re: What’s the most practical way to swap engines?
 

I went with EPAS electric power steering, clean and simple.

Re: What’s the most practical way to swap engines?
 

It currently has a 6 cylinder. Well...most of one 😄. I’m not sure what gears are in it. I’m on a budget but not a time line. I like the idea of a donor vehicle. What engine/tranny combo did you get out of your parts truck? I’ve noticed there are “bolt on” motor mounts for a 350 in these trucks. Don’t know how straight forward those are.
Thank you

Re: What’s the most practical way to swap engines?
 

I will definitely look into this. I wondered if it was possible to utilize the power steering pump that came in whatever engine I put in it or if that would just be opening up a huge and possibly unnecessary project. I’m pretty much a newb when it comes to this. I’m sure I have bit off more than I can chew but I’m in no hurry.
Thank you for this idea

Re: What’s the most practical way to swap engines?
 

I started with similar notions about keeping it stock-ish in the front suspension.
My experience is that by the time you add disc brakes, power steering, new bushings, new steering joints, etc you have spent darn near what an IFS might have cost you.
I've got new shackles, rear spring bushings, new king pins, new tie rod, C10 power steering (avoid like plague), disc brakes, tapered roller bearings, 4* caster wedges and probably some other junk into my I-beam front end.

It handles and steers like a boat, parks like a garbage truck and buzzes like a summ***** going down the freeway. With a Chevy 350 & 7004R you will have the power and gearing to go a lot faster than your front end will really keep up with. It still needs a ton of work to be "right" - partially because the C10 steering kit is such an engineering junk-show to begin with, partly because you are still gilding and spending money on 1957's worn-out parts that were designed well before interstate travel was hitting 80 mph.
Possible caveat there is that if you have really tight kingpin and spindle bores or go with a new drop axle, your junk will probably not buzz like mine does.

Re: What’s the most practical way to swap engines?
 

do you mean cheapest or literally the most practical? I dont want to assume one or the other but a lot of people use "practical" when they mean "cheapest"

the most practical way would be to buy a complete donor like mikebte suggests and take out every single part you need to swap over. I have a theory that a wiring harness/drivetrain doesnt inherently KNOW what chassis it is installed in, it just looks for certain inputs, and if you can make sure it has those inputs you will have a working system even with it laying on the ground. in aerospace they call it an "iron bird".

then look at what you cant reuse but need to. for example your donor may be a column shift auto but you cant add that to your stock column. your donor may be EFI but needs the harness pared down and a different gas tank with the same pump. lines may not switch over.

the easy part is mounting, buy or more likely build the mounts.

Re: What’s the most practical way to swap engines?
 

I’m sure you are right on IFS handling infinitely better then these old things. Maybe one day I’ll go that route but initially I’ll keep the front axel as is. It won’t ever be a daily driver. I will drive it in town, 10 miles to the next town or 25 miles to my parents. Nothing over 55 mph.
Thank you

Re: What’s the most practical way to swap engines?
 

I looked this morning on cl and found many possible donor vehicles with the engine/trans combo I think I want. Even auto with shifter on the floor which I want. What I’m wondering is about the wiring. They sell new harnesses for these truck. The newer the donor truck the more dependent on computer crap. Is there a range of year I should be looking for in a donor? What I want is minimal issues with a new harness and a donor drivetrain. I know I’ll have some.
By practical I mean what makes the most sense. What’s going to be the easiest. I’m in no hurry to have my finished project. This is just something to put my head into and take it off of the normal issues with life. I guess I would call it a hobby.
Thank you
Jason

Re: What’s the most practical way to swap engines?
 

its pretty simple these days to use a modernish (98-2010) donor and just buy a stand alone harness, you will need someone to flash the pcm for standalone but literally 8 wires to hook up. getting the right fuel system is the next hurdle, usuing the donor pump is the best way if you can pull it off. then cooling system, then gauges.

Re: What’s the most practical way to swap engines?
 

for x-members the most practical way i have found is to fabricate your own
most inexpensive x-members are universal fit and need to be cut, fit and welded
why cut, fit and weld someone else's metal?

power steering is a slippery slope. you'll need a new column as the old column is integrated into the steering box
if you decide to go ifs all your work/money comes out into the junk pile
yossarian has some good info in his post, reread his reply ten times :D

Ok so if I went IFS, what are my best options?
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Re: What’s the most practical way to swap engines?
 

honestly, look for a V8 truck or car, shifter location can be moved no matter the platform. Get a used car or truck and move over everything you want. In my case with the 93 GMC I used the entire cab harness from the 93. I now have courtesy lights, newer wiring, fuel injection and the fuel pump wiring was already in the harness and it was very simple. It will be a little time consuming if you are using the old harness as you have to figure out the locations for wires when doing a custom gauge install.

As for newer engines, the electronics are not bad. Many of them will last a long time and you get the ease of fuel injected start ups and an electronic shift transmission.

If you get a truck as a doner, the cross member may only need shortened and bolted in, the engine mount will be the biggest custom part you have and that is very easy.

You can also use this kit, easy enough.
https://www.summitracing.com/parts/c...etxk/overview/

Also check out other builds. I have taken so many ideas from the folks on here that its crazy. I found that OrrieG used a foot brake pedal out of a 70-80s blazer in his truck. So i adapted the same idea and it was super easy.

Mainly, its your build. Have fun and keep it unique.

Re: What’s the most practical way to swap engines?
 

Thank you
I have been poking around this forum for awhile trying to decide the best course of action. Trying to decide which way I want to go. I’m still not sure. I know EFI is nice, not sold on it. Kinda like the old school carb. Is figuring out the wiring going to be more difficult using a newer donor compared to an older one? I’ve never done auto wiring. I rewired my whole house tho 😁. Yes I know that it’s completely different lol. I was hoping I could just buy a new harness and plug everything in, ripping out the old as I go. Nothing is that easy. If I was keeping the original motor that would be more if a possibility I’m guessing

Re: What’s the most practical way to swap engines?
 

I like using all the EFI and harness too, but it can get kind of crowded under hood.

https://farm2.staticflickr.com/1905/...2bdd24c8_z.jpgIMG_2168 by Joe Doh, on Flickr

Re: What’s the most practical way to swap engines?
 

Shocking. I've had three I-beam axle trucks and all rode and handled great, both on winding rural roads and at freeway speeds. I can't imagine why you've had those problems but that certainly hasn't been my experience at all.

Re: What’s the most practical way to swap engines?
 

Both have advantages. My '57 has had EFI since the early '90s. It was more complicated to set up but I have had to do very little maintenance to the engine to keep it running since that time. My '36 Plymouth is still stock retaining points and a carb. It is very easy to service. Good thing because every year I have to clean and adjust the points, clean the sediment bowl, and clean the carb before the summer driving season begins.

Possibly. There are many more circuits in the newer vehicles and if you use a harness from a donor vehicle you will need to make decisions about which ones to keep and which ones to junk. But the popularity of the LS swap means there are many sources of help if you decide to use an LS engine.

You can buy pre-made harnesses for nearly any engine /computer combination you might want to run. Many folks find that easier than ripping apart an OEM vehicle harness. Although quality plays a big role in harness pricing, it's also true that the cost of the harness will be proportional to the amount of work you are willing to invest on your end. A harness tailored to your truck, with length and circuits you specify, to connect to the engine and computer (and possibly transmission) you installed, will require a hand-built harness at greater cost. A generic harness which you adapt to your vehicle is likely to be less expensive.

I would say it might be tougher. The original motor was never designed for computerized engine controls so you would be integrating sensors, injectors, and an electronic distributor which would add time and complication to your project. Retrofitting an old engine to modern electronics such as distributorless ignition and port fuel injection could be considered an advanced level project compared to removing the old engine and dropping in a complete donor vehicle engine.

Hmmm... considering IFS because it's better? LMK when you start the IFS swap in your Jeep. ;)

Re: What’s the most practical way to swap engines?
 

lol wont be doing anything more to my Jeep. Love it just how it is. I imagine the 56 will get about the same amount of use as it does. No highway(well twice in the 3 yrs ive owned it, that includes driving it home lol). maybe 5k miles a year driven
I love the look and nostalgia of these old trucks which is why i dont want to have to veer real far from stock. i know I will have to in some degree and might decide to as the years go on but for now ill change only what is necessary. will it ride rough? probably more so than my grand cherokee but thats what i want. If i could have found a survivor that had drivetrain in it than that would have been awesome. Instead i looked for the best cab and frame i could find and went with that. Got pretty lucky in that department. a couple cab corners to weld in and thats it.
thank you for your response

Re: What’s the most practical way to swap engines?
 

tell me if this is way off base pls. find a donor from 87 to 92 that has the 350/700r4 that im looking for and use as much of the donors wiring harness that i can. I can find a crossmember that conforms to this frame and matches up to the 700r4. Ive found engine mounts that do the same as well. Im new to this extensive automotive work so ple tell me if im heading into a complete nightmare that isnt likely to work.
My Dad has rebuilt a few cars in his day and has every tool one could want except a lift. He will be a big help i have no doubt but he is also a mopar/jeep guy(as i have always been, but this series of truck is too sexy to pass up lol). I already got the raised eyebrow when i told him about it.

any and all comments and info is appreciated. Im just trying to learn and not make too many costly mistakes. This is going to be my pasttime for the next few years so in getting it road worthy anyway.

thank you again to everyone who has commented on this thread

Re: What’s the most practical way to swap engines?
 

Sounds completely logical. 87-92 you have a good choice on 350 (TPI/ TBI/ Carb) and the 700R4 is not a computer controlled transmission, so if you opt to run the carb it will work just fine.

If you run into any issues on wiring, you know were to find all of us.

Re: What’s the most practical way to swap engines?
 

I've always been a fan of buying a running driving donor for a project as long as it has the correct engine and trans you want for your project. That might be reasonably easy where you live as you can hunt down the good running V8 "winter rig" They may not be as cheap now as they would be in the spring though. That good running mid 80's two wheel drive pickup or maybe ex cop car caprice that runs great but is all rusted out might be a good cheap donor that you can sort out the engine and trans before you pull them.

Yeah I think that’s what I’m going to do. They are all over cl right now and I’m sure they will be in the spring as well. I won’t be doing much this winter other than acquiring things that I need for it.
Thank yoy
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Re: What’s the most practical way to swap engines?
 

You say you are going to do a lot of around town driving and no high speed driving and nothing over 55mph. Don't mess with a 700r4, just put in a turbo hydro 350 tested tried and true. The 700r4 is for computer engines that run slow, about 1500rpm. A carburetor engine needs to run above 2000 rpm to work well. Most people don't know this because carburetors were phased out in 88. A Q jet 350 and a turbo 350 are the perfect combination for occasional use and slow speeds around town. No wiring headaches, you can fix anything on it, and it is going to sit most of the time so why make thing complicated?

Re: What’s the most practical way to swap engines?
 

yep, if you want easy and quick buy a GOOD runner, not something that "just needs a tune up" or do the tune up while it is in the runner still. then take it all apart and slip it into your truck. these trucks came with a small block so you should be able to find mounts easy enough. the issue may come with the ifs swap because the original engine mounts are front mounts. you will also need to fit up a trans cross member but keep in mind that the original tranny cross also supports the cab and front spring rear mount areas for stiffness. you may wanna look at keeping some support there.
check out a few threads here, lots of those style of swaps.

Re: What’s the most practical way to swap engines?
 

Hey I'm in your shoes and learning and this is what I'm told so far and trying for myself. my mechanic calls it my practical poor man plan

1988 to 1991chevy or gmc 2wd truck is what to look for if you want less wiring and flashing computer stuff. Once you get to 1992 you have the electronic tranny. has the tbi engine for fuel injection and the 700r4 then you supposedly can use lots of other stuff like suggested above out of the donor vehicle. but I liked his idea cause I can buy the truck and drive it and make sure everything works before putting in my truck. since you won't be drivin it a ton you buy one with around 100k and supposedly you will have an engine for the rest of your life haha. plus I'm not a person who can keep my carb tuned up and the fuel nowadays seems to make it harder he claimed.

there's a guy on Facebook Seth doulton in a Chevy/gmc forum I think that does really reasonable priced custom wiring kits I hear good things about. but there's tons of wiring companies just have to decide how much youb want to spend he's like $250 I think so much cheaper than alot i found.

it's an adventure. I originally planned to do like you and just upgrade my stock frobt with disk brakes and such but have since decided on a mustang ii after listening to these helpful gu ys on here. the cost and the benefits of what you gain are worth it to me since I'll be driving in town and need good handling and brakes and the cost of adding disk and powersteering was getting close so I'm saving for the better handling bonus as well haha

good luck and welcome. this forum is amazing and I have learned a little and have much to go. enjoy your build

Re: What’s the most practical way to swap engines?
 

:confused: Huh?

Re: What’s the most practical way to swap engines?
 

A carburetor engine needs vacuum and mechanical advance to run it's best. Full Mechanical is at about 23-2600 rpm and full vacuum is at about 2000 rpm. Running the engine down the road slower than say 2300 rpm is not good for gas mileage and not good for the engine either. The reason to put an overdrive transmission in something is to get better mileage and less engine wear. Very hard to do with an overdrive trans hooked to a carburetor engine. The OP said he likes carburetors and he wants to keep the original suspension and he plans to drive around town and occasionally a few miles out of town. With this info a 700r4 would not be the best trans for him. Buy something like a 1975 Nova 4 door in nice shape and take the 350 engine and Quadrajet carb, th350transmission, driveshaft, and rear-end out of it and put them in the 56. Very straight forward simple swap. This way you have exhaust you might use and E brake cables and
lots of other little stuff too.

Re: What’s the most practical way to swap engines?
 

I've seen head to head tests (Engine Masters / Motor Trend) and the carb did just as well as injection. Injection is much easier to tune. A crank fired ignition will benefit any engine for tuning advance curve. I'll be running 3 Roch 2 bbl's progressive linkage, crank fired ignition and a 4-71 blower on my 292. Gaerte Racing Engines tells me it will do just fine. They also said it was going to be a pain in the a#* to tune to start with. I think the carb's look a lot cooler.

Re: What’s the most practical way to swap engines?
 

all the previous stuff aside.
first, decide what your budget will be.
second, decide what you want to end up with
third, be truthfull with yourself (and your partner if there is one). do a complete and thorough check over of what you have and what it needs. do some legitimate pricing on the parts you will need and any labour you can't do yourself.
fourth, decide if this is something you want to invest in or can afford to invest in. is it gonna cause trouble in the household when time and money are spent on "that old wreck".
start with the underpinnings, get a good base to put everything else on top of. if the body is in good shape then thats great. you can drive it around with a couple of bad cab corners but driving with worn out suspension and brakes could be disaster. start with the base and build off of that.the problem here is that you really should take the body off the truck so you can ensure the frame is really in as good a shape as what you think. do some checks to ensure it is square, straight and doesn't sag. check the crossmembers for loose rivets, cracks, rust between the mounts and frame etc. it's not a bad idea to dissassemble the entire thing and have it blasted so you know exactly what you have before you start. the area around the front shock mounts, for example, can rust badly over time and be almost through the frame thickness if you remove the bracket and blast the area till you see good clean steel. the same goes for the rear suspension mounts. anyway, all I am saying is do a thorough checkover of the most important part of any vehicle-the part that supports the suspension, body, and driveline-the frame.
check the entire truck and make a list as you go. be truthfull and don't skip over anything. price out the parts to fix it the old way and then price out the parts to fix it like you want to end up. sometimes the cost to repair the old will go a long way towards replacing the old with the new design that you want in the end. when you say it will be short trips around town, that, to me, says ifs and p/s, p/b. highway driving isn't so bad with a straight axle, not really any short turns to worry about and not really any quick stops in stop and go traffic.to me, ifs would be more of a "must have" for city driving. for long trips a solid axle would be ok (but I would still WANT ifs,lol).
if you find the front end and suspension are ok to drive as is, then the other option is to drive it that way while you fab a whole complete new frame with the suspension you want. then,when complete, swap your body and driveline over.
if it is simple you want for a driveline choice, and city driving is all you will be doing mostly, then a good running carbed 350 with a turbo 350 behind and a good rear axle ratio will be all you need. if you find things change and road trips are more your style you can always swap in a 700r4 later. if you want to upgrade to fuel injection then install a good running LS engine and get the computer remapped for your design, gear ratio, exhaust etc. the LS, in my opinion, is the new small block chevy. sorta like the old days when everybody was swapping in the small block where the old inline 6 used to live.
thats just me though. if you love the small block then do what you want, it's your hotrod. electronic engines will also need some sort of speedo revamp because there is no speedo cable adapter in the trans. more money to account for
in the end do a check of what you really have and what needs you have, then do a study to back up your plan. then look at it like someone from the outside would and decide, logically and budget wise, what your plan will be.
most importantly---take pics and post them as you go.

Re: What’s the most practical way to swap engines?
 

dsraven, well said.

Solid advice, thanks. Most of which I had done before ever buying the truck. I would hope most ppl would have a good grasp on the financials before stepping into a project like this. Sure there are always hidden costs. Fortunately for me I am in no hurry. So if it takes 5 yrs then it takes 5 yrs. My wife is onboard with everything as long as I don’t hock her jewelry to do it 😳. I know I want to keep it as close to stock as possible. Im looking for that simplicity. I know I won’t be taking long road trips. I have new vehicles that would be more comfortable for that. I’m not interested in ifs or LS engines. So this post was just looking for advice on what would be the simplest and practical drivetrain swap for a mostly stock truck of this age. Less wiring issues. Less compatibility issues. And how to go about getting it.
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Thank you. I’ll keep an eye on cl for this.
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Re: What’s the most practical way to swap engines?
 

If your wife is on board with this project then you have 90% of your problems solved already,lol.

Re: What’s the most practical way to swap engines?
 

if it is just a power plant and trans you're looking to swap in, make sure to do a complete check of the engine and trans before shelling out the cash for it. oil pressure cold and hot. compression dry and wet. spark plug condition (sooty, oily etc). pull a valve cover and look for sludge etc. a complete running vehicle can also be pressure tested for cooling system leaks (like head gaskets etc). if you plan to "reseal" the engine then you might as well do a timing chain and gear set, valve seals, rear main etc. you can see how the prices can build on you quickly and come closer to being equal to a rebuilt. pull the trans pan and check for excessive black (usually clutch pack material indicating the clutch pack wear) or brass and/or aluminum pieces indicating bigger problems.try to pick up a complete running vehicle, possibly an insurance write off from body damage. a sport model with a stock 4 bbl carb may indicate a 4 bolt main block and big valve heads. most of the stuff you need will be in the donor vehicle you're scrapping. brackets etc. with that said, however, you are still gonna find that those parts may not fit. the accel pedal from a car,for instance, may have the totally wrong angle for a truck but is still not a deal killer. it makes some sense to make a list of all the parts you will need and price them individually from a "new parts" source and go from there. things like engine mounts may not be worth installing from the used engine due to age cracking or oil contamination. price out a rebuilt or crate engine compared to the used. same for the trans. if using a turbo 350 you may be able to source a rebuilt for not much more than the used.
just some ideas. if just cruising town with the old fashioned suspension then the engine/trans combo can be pretty basic as well. you could even use the stock trans cross member if you went with a std trans. there are bellhousings out there from the stock v8 that will wok and then you could use stock v8 engine mounts that attach to the front of the block. these trucks did come with the v8 option but would have had the old granny 4 spd tranny or 3 spd versions or, if you could still find one, a cast iron automatic trans that weighs as much as the truck.

Re: What’s the most practical way to swap engines?
 

Just about everyone on this board has more experience than me but I think my approach to the old truck was/is similar to yours. We have a 56 GMC in our family that sat for decades and I simply wanted a running, driving project. Maybe I could drive it to work once in a while on a Friday, to the dump or Home Depot if needed and always have something to tinker with when I had the time and inclination. It has a 283 and a four speed manual with a granny gear. I spent a bunch of time cleaning it up, trying to stabilize the deterioration of sheet metal where needed and getting the motor to run and the brakes to work. That was a big accomplishment. It needs a million things but I can drive it around now, it isn't rotting under a tree anymore and I can choose projects to take on as I feel like instead of getting bogged down in a major rebuild that might take years.

In your case, I might look for any old running GM motor that's available at a reasonable price that you can conveniently pick up. Looking through Craigslist near me, there are quite a few options--especially small and big block GM motors. From free to a few grand. Next, find a trans that will work. Again, quite a few near me that would work at a reasonable price. Then you can work on how to mount them and if major/minor work is needed, you'll know what questions to ask. You'll need some books and if you have any friends or family that know their way around old cars, enlist them occasionally, and then the endless knowledge, experience and expertise of the people here.
The great thing about these projects, especially the drive trains, is that they are so common and simple, lots of people have experience that you can learn from (parents, uncles, neighbors, forum contributors) and you can figure a lot out on your own.

Anyway, just thought I'd chime in since it seems like I was in a similar place a year ago. Once I decided that the priority was to have a drive-able truck and that lots of things could wait (paint, weather stripping, the perfect seat cover, windshield wipers, new shocks and springs), it got a lot simpler and I was able to make good progress knowing I'd have to retrace some of my steps when it was time to make improvements.

Re: What’s the most practical way to swap engines?
 

Thx for the response. I’ve decided to do a frame off restoration. Since the fuel system is so old and needs replaced and the electrical and brake system is equally as bad it just makes sense to me to go that route. This truck sat for over 20 yrs and I feel if I just don’t go thru the whole thing I will be constantly chasing gremlins. I have picked up a couple books, one of which is a factory assembly manual. My stepdad is quite knowledgeable in regards to car restoration having done a few over the years and along with his vast array of tools I think we will tackle it. I’m sure it will take a couple years, maybe more but that’s ok with me. It’s just a hobby I’m looking to enjoy.
From what I have read, mostly on this awesome site, it seems that an 80s Camaro or Trans am might be the sweet spot if I can find the right one. Net me the 350, auto transmission and a posi rearend. I recently found out my brother in law has a good friend who owns a local salvage yard so might get lucky there.
I’ve lined up a local media blaster to do the frame and cab for me in The spring. In the mean time I will hunt down the patch panels I know I need now(likely to need more after it’s blasted). Find a few missing parts and cram as much information into my brain until spring gets here when I can start disassembly. Unfortunately my garage is small and I can barely get my TJ in it during the winter so I can’t do much until better weather arrives. Oh well, gives me plenty of time to formulate a plan and get everything found and/or lined up.
Thanks a bunch

Re: What’s the most practical way to swap engines?
 

Sounds like a good plan-- Keep us posted!