Old truck - New engine

96 Vortec · July 15, 2003

Well folks, I might not be driving my 96 K1500 for much longer. Today I was rear ended and it appears that the frame was shifted in the accident. I don't know what the repair bill is yet, but I wouldn't be suprised one bit if it was totalled.

I have been dreaming about having a 73-79 Suburban for some time now. Today a friend suggested that if my truck is totalled, I should buy it back and swap the motor and transmission into and old Suburban. He also suggested that I could dress up the interior from my truck with the power buckets and center console. I really like the idea but how feasable is it? Would it just be more trouble than it is worth? The plus side would be, I already own the truck so if I swapped the motor and all associated electronics, I can be assured that there is nothing missing.

How hard do you think it would be to make everything functional in an older vehicle? What pitfalls would such a project entail? Anybody have any experience with a swap such as this?

Thanks in advanced for any comments or ideas.

Instrument 39 · July 17, 2003

Never done engine swaps but restored a few vehicles, frame ups. The amount of frustration is directly proportiobnal to your skill, a place to do it, and the correct tools to doit, the swap that is. If you go with a Burb the older ones were known to be rust buckets, so be prepares to do some body work. The cool thing is to find a 68 to 72 burb. harder to find but much more robust than the following generation.

acjones20 · July 18, 2003

I am by no means an expert on these things, but I do like to read about engine swaps and custom stuff and it seems that the easiet thing is to keep it as close to stock as possible. If you can find a burb that had a 350 and th400r (were they even offered in that year??) then your 350 and 4l60e should seemingly bolt up. I believe that the 4l60e is the same housing as the turbo 400 just electronically controlled and any SBC should be a bolt in. I would imagine that custom driveshafts and the like would be needed, but you could save cost and cut your old ones. Getting the interior things might be trickier. Anything self contained like a seat could probably be made to work (might have to fab up some brackets) but things like gauges and other things could get interesting. Painless performance has hot rod wiring harnesses that are basically fully customizeable or you might could integrate your old one if you are good w/ wiring. If it were me I would sell the motor on e-bay and get a new ramjet 572. that'd be a burban

Larry · July 18, 2003

96 vortec,

Sorry to hear about your loss but your loss does yield some very nice donor parts to play with. I haven’t done a swap such as this on any of my vehicles yet although I work for a commercial truck manufacturer and have worked with many of my fleet customers on swapping in L31 engines into older Chevrolet and GMC P-chassis stepvans (breadtrucks, Frito-Lay trucks, UPS trucks, etc) that originally had 250 and 292 I6 engines or carbureted small blocks. I am also getting ready to fuel inject a 454HO that I just bolted into my 78 K10.

As far as swapping your L31 350 into a pre-fuel injected truck is also proportioned to your skill as Instrument 39 mentioned above. If you pay a shop to do this forget it…a project like this is only feasible if you can perform the labor yourself.

Obviously your L31 will be a direct bolt in to any older Sub but you will have a few choices when it comes to the engine management system. You can either painstakingly surgically remove all the uncessicary wires from the Z71 wiring harness that are not needed to run the engine and 4L60E slushbox trans...which takes a lot of skill and a good understanding of OBDII and basic electronics then create your own wiring harness. In my opinion this is the worst method….but possible if your good at that kind of stuff.

You could also check the wiring harness offerings available in the aftermarket such as Painless Wiring or Howell EFI. These are good but you will still have to run OBDII with all of the aftermarket wiring harness kits that I am aware of which means you are screwed with out an expensive scan tool to check for fault codes just as you are today if your Check Engine Light came on your Z71. Trust me…you will have plenty of fault codes that will have to be taken car of once you start messing with that many wires as something is bound to go wrong. Something always goes wrong. GM has also created a wiring harness kit to retrofit L31 engines into older P-chassis trucks that I spoke about above but this is not a free flow part number available through any dealer and only sold directly to National Fleet Account customers so forget the GM kit. You would think GM Performance Parts would snake that kit number right up for the street rod crowd but nope.

Again, my opinion only, the best method to retrofit newer powertrains into older vehicles to go with GM marine wiring harness and engine controller from a boat that runs an L31. You can purchase these harnesses and controller from most Marine dealers that sell boats with GM Powertrain engines. You will have to do some fandangling to these harnesses and rig up a Vehicle Speed Sensor signal which can be done with aftermarket parts but that is very minimal compared to the other options. You will also have to change you accelerator pedal to a very late model (2003) electronic pedal assembly as no throttle cable can be used. This also means you will have to change the throttle body on the engine to the electronic marine version as well since L31 small blocks were never available in automotive form with a Throttle Actuation Control module. The best part is you can run these on OBDI like an early 80’s though 1995 GM vehicle and still have port fuel injection for most years of marine applications without smog retrictioned pony robbing fuel and timing calibrations.

That is the route I am going with my project. Like I say, I have a 454HO that is set up like a late 90’s L29 454 but currently with a carburetor. YUK! The good news is I just came across a complete 1999 GM medium duty truck LP4 454 sequential port fuel injected intake for a very good price. The other good news is the LP4 454 basically used all PCM and wiring as a marine applications with 1996 though 1999 big blocks so that is the route I am planning to go. One of my counterparts that works in GM Powertrain side of the business teaching me on this late model EFI swappage using all readilly available GM part bin components to help our fleet customers that are repowering older trucks. We’ll see how well all this recently acquired education works once I apply this entire BS into a 78 K10 apposed to a 1980’s bread truck.

Here is my new big block awaiting EFI.

As far as the transmission and transfercase you will have to use an early NP241 with a right side front output shaft as you 96 Z71 has a left output shaft. The trans will bolt right in except for some minor shift linkage fangling but you will have to purchase a stand-alone controller from someone like TCI to run the 4L60E. Boats don’t use those trannies

Sorry for the long post…I just find late model engine swaps intriguing.

BLKESC · July 21, 2003

This is just a thought...What if you took your '96 motor (and trans) and sold it to get a crate engine? Then you could get an aftermarket FI setup like Holley or whomever else if you wanted. It might be worth researching.

96 Vortec · July 21, 2003

Well, this idea has been shot to hell. I just got off the phone and they have decided to fix my truck (as I suspected). They did list on of the repairs as "Frame Straightening". So, upon the return of my truck I'll be trading it in.