CUCV Diesel Swap

[taquito971]

I have a 1979 GMC K3500 crew cab truck. It's powered by a 350 with an SM465 4 speed. I get terrible fuel mileage and I'd like to repower it with the help of an M1008 CUCV. I would pull the entire drive train from the CUCV including the axles (for the rear locker) and the T400 (cuz I'm lazy and don't want to shift anymore).

I believe I can make this happen, but I have a few questions. Maybe you guys could help me out with the answers.

1. Air Conditioning- any idea of the OD Iron kit will mate with my existing controls in my '79? I understand that the dual alternators and such create a unique obstacle. But maybe someone is familiar with GMs and knows the answer already.

2. Exhaust-Will my existing exhaust system bolt up to the stock manifolds on a 6.2? My 350 has stock manifolds right now.

3. Wiring- Any idea how difficult it's going to be to get this thing wired up? I don't have a lot of options like power windows/doorlocks/cruise control but I do have Air conditioning, a radio and the basic array of guages. I assume no one makes a direct harness for this application (actually 1-tons and diesels in general seem to be overlooked all together in the direct aftermarket). Any hints?

3. Registration/Smog- Any California residents tried this swap? Anecdotal evidence suggests that if the truck had a diesel option that year that swapping in a diesel and getting it changed at the DMV is fairly simple. As long as I don't get the BAR involved. Anyone got any TTPs to share?

Am I crazy? I feel confident that it can be done, but maybe that's because I'm overlooking something obvious. I'm not looking for a high horsepower tire roaster, just something that is a good reliable DD and can tow a trailer occasionally.

Brian

 

[Warthog]

1. no idea

2. manifolds will have to be changed

3. If you are installing the 6.2 in a 12v truck, you can do away with the second alternator and 24v system. Just run 12v. You will only need to change the starter out for a 12v.

The only item needed to make the diesel run is the 12v fuel solenoid on the injector pump. Wiring should be easy.

4. With the NEW California rules about deisel engines you may have an issue with inspections. Check before you start. I know alot of local governments are being forced to purchase new vehicles because of this.

 

[1984M1009]

There is no emissions on diesels older than 1997 in California but I would still check with the state to make sure you can continue to register it

The 4.56 are probably too low if you are going to be driving this truck daily

if it was me I would keep the 465 and add a ranger overdrive but I hate automatics but for some reason I own three Figure that out

 

[taquito971]

Warthog,
By "manifolds will have to be changed" what exactly do you mean? Do you mean that I can't use the stock 350 manifolds on the 6.2 or that the 6.2 manifolds will have to be changed? I never figured the 350 manifolds would fit on the 6.2. I suppose my question was more centered around whether the exhaust that is mated to my stock 350 would mate up to a stock 6.2. It probably wont, but a man can dream can't he?

I would rather retain the dual alternator setup (not sure why, just because it's cool I guess) but maybe removing one alternator would mean I could use my stock A/C compressor... Anyone know that answer?

As was mentioned, I don't think smogging the diesel is required, my main concern was getting it re-registered as a diesel when it originally had a gas motor.

Thanks for your input!

 

[taquito971]

1984 M1009,
My last few vehicles have all been manuals, I guess I'm just getting tired of shifting... And as far as clutches go, the one in that 465 is actually pretty nice, I just don't think I really need the granny low and such.

I did not mention it but I had planned on Hummer wheels and tires, so the gearing should be fine with the oversized tires.

Any idea who with the state would know for sure if I can re-register it? I would think the local DMV would be sufficient, do you agree?

Thanks!

 

[ABN173]

I believe you will have to change out the glow plugs too as part of your conversion to 12V.

 

[taquito971]

Wellman AC60s right? Thanks for the reminder!

 

[Midnight Rider]

I believe you will have to change out the glow plugs too as part of your conversion to 12V.

I was under the impression the glow plugs were already 12V. I thought there was a resistor on the firewall that stepped the 24V down to 12V for the plugs.

 

[hre513]

Warthog,
By "manifolds will have to be changed" what exactly do you mean? Do you mean that I can't use the stock 350 manifolds on the 6.2 or that the 6.2 manifolds will have to be changed? I never figured the 350 manifolds would fit on the 6.2. I suppose my question was more centered around whether the exhaust that is mated to my stock 350 would mate up to a stock 6.2. It probably wont, but a man can dream can't he?

I would rather retain the dual alternator setup (not sure why, just because it's cool I guess) but maybe removing one alternator would mean I could use my stock A/C compressor... Anyone know that answer?

As was mentioned, I don't think smogging the diesel is required, my main concern was getting it re-registered as a diesel when it originally had a gas motor.

Thanks for your input!

Depends on the manifolds you have. I know that an exhaust from a certain set of gas manifolds will bolt up to a certain set of 6.2 diesel manifolds. I did it once. The small block manifolds I think were from late 70's early 80's. The 6.2 manifolds were from an 80's pickup which were the same on the cucv. If you look at them you can kinda tell if they will line up.

 

[Ken_86gt]

I was under the impression the glow plugs were already 12V. I thought there was a resistor on the firewall that stepped the 24V down to 12V for the plugs.

Correct.

 

[ABN173]

I was under the impression the glow plugs were already 12V. I thought there was a resistor on the firewall that stepped the 24V down to 12V for the plugs.

It seems I was misinformed by a mechanic at work (go figure), here is what Doghead said on another thread:

Don't be confused.

* Fact, the original cucv GP system supplies, 24v BUT, it goes through a resistor bank and that DROPS the voltage down to 12v, as soon as all 8 good glow plugs get the voltage(Yup, it's electronic magic)

* The magic does not happen when one or more glow plugs are bad or disconnected. This was a compromise in the original design.

* The glow plugs(Wellman 070, AC60G, AC13G, etc.) are all actually rated at 10.5 v!

Do not be confused!

 

[hre513]

I thought they were 6 volt? I hooked a hot wire to one outside the engine and noticed it heated up faster than a 12 volt from a 350 diesel.

 

[taquito971]

Interesting, in the FAQ article, it recommends two different glow plugs. One for stock 24v one for a 12v conversion.

 

[wholden]

I use the 60G's with in the stock 24V system and they work great. The original ones were all swelled up when I removed them and I got REALLY lucky pulling the stuck one in the right rear!

 

[akonitony]

I got REALLY lucky pulling the stuck one in the right rear!

Isn't that illegal in like 7 states?

 

[Cucvnut]

i dont think it will pass the CA ref board for the motor swap. 79 trucks are still smogged so you need to take everything from the Diesel truck and put it in yours in order to pass the ref board. you will need to take the truck to the dmv ref and have them issue you a new vin saying your truck is diesel. i would contact the dmv before you do this to find out swapping a gas powered truck to diesel. also the 6.2 in a cucv is a federal motor not the same motor that came in stock CA diesel trucks.

 

[taquito971]

Understood. What exactly do you figure would be required from the 6.2 CUCV other than the motor? No catalytic converter, and I plan to use a muffler.

As for the 6.2 CUCV motor being a federal motor would it not have been an available motor for an '83 1-ton in California? I guess I just assumed it was. I had not heard of a CA specific 6.2 before. Never really looked into that angle. In '79 I think they were using the older Oldsmobile diesel anyway but I didn't figure that would matter.

IMO the diesel I would be putting in there would be from a newer vehicle in the same family (GM/Chevy HD truck). I suppose that won't stick if there is a different 6.2 (or modded 6.2) for CA during that time.

Unfortunately my local DMV office is closed for remodeling until next month (seriously).

I read somewhere that others had swapped diesels into non-diesel vehicles in CA and did nothing but inform the DMV counter rep. that it was no longer a gasoline motor. A quick VIN sticker later and it was a done deal. Of course I probably read that on the internet...

 

[taquito971]

Found this on another forum:

I just spoke to CARB and what sounded like a very knowledgeable gentleman. He basically said there are three basic rules that make up their policy toward engine changes in CA, and if you fail any one of these, the referee will fail your conversion (sometimes they'll fail it anyway because they don't want to have to deal with the vagaries):

1.) Donor engine must come out of the same year or newer vehicle.

2.) Donor vehicle must be in the same weight class as the receiving vehicle (this rules out the Isuzu 4BD1 as those were all put in medium duty trucks with higher weight classes). The CARB guy said that a lot of times the referee will ask for the donor vehicle's VIN or registration, to prove that you didn't get it out of a delivery truck, or a boat! However, he did say that (in California at least) you CAN put brand X engine into brand Y vehicle, as long as you meet these three criteria.

3.) The donor vehicle and engine must have been certified as a California-legal vehicle when sold new. This pretty much rules out everything else except maybe some of the Mercedes diesels in the passenger cars, some Volkswagons, and the domestic diesels, none of which I personally would consider (well, maybe the Merc if they were still bringing in the diesels in 1994, the year of my 80 Series that would be the conversion candidate - but they weren't ).

 

[Cucvnut]

What do oh thinly will do?