Diesel Conversion

[Firearmfiend]

OK guys and gals, here's one for you. I'm converting my '70 C-10 to diesel. I'm seriously thinking of using a Cummins 6AT 3.4L (about the same size as a 292) but would consider using a Cummins 4BT or GM 6.2L.

My main question is this: Any thoughts or concerns with these motors? Also, what should I watch out for technically when it comes to the nuts and bolts of the conversion (glow plugs, fuel delivery, dual batteries, etc.).

Any of the motors I'm looking at come with the Chevy bellhousing and step van motor mounts. On the Cummins motors the clutch fork is on the wrong side of the motor so I already know I will be using my old bellhousing and replacing the clutch (who knows WHAT those delivery drivers were up to! )

If you've done this conversion a response would be greatly appreciated!

[Beefcake]

6.2/6.5 would be a lot easier because of the footprint. But its a pile of junk. If starting from scratch, cumming, dont forget the 7.3 powerstroke

[67_C-30]

Originally Posted by Beefcake

6.2/6.5 would be a lot easier because of the footprint. But its a pile of junk. If starting from scratch, cumming, dont forget the 7.3 powerstroke

I have had 3 piles of junk (6.2/6.5) in 3 different trucks. My '91 C3500 had over 260K on when it the new owner drove it off. My '83 Suburban had 230,000 when the new owner drove it off 5 years ago, and he's still driving it today. My '84 K1500 has 330K on it, and I drove it Sunday.

With that being said, I'm currently swapping in another pile of junk in my '67 C-30 dually. I've already logged around 500,000 on these piles of junks myself already. I guess another couple o' hundred thousand won't hurt anything.

[Firearmfiend]

Keep the replies coming, PLEASE!!! By the way, I'm not doing this swap because I finally saved up enough money or something, I'm doing it because my current PIECE OF CRAP!!! Kragen 350 (yeah, I know, but I was really poor then) finally took a real s__t on me and for just a little more money I can go diesel, eventually to go to a straight veggie oil conversion.

Beefcake-- Can't afford a Powerstroke... besides, can't afford adapter bellhousings, can't afford different tranny (I have a tranny, divorced t-case, and front axle out of a '66 K-10, but most of that's a different thread entirely!)

Also, can't afford adapting a 12-valve 5.9 into my C-10, sorry, not to mention, I really despise electronic controls and doesn't that Dodge have a few?

67_C-30--I've heard good and bad things about the 6.2... I'm glad to hear you've had good luck with them. Were your's turbo'ed or naturally aspirated?

Again, thanks guys, keep 'em comin'!!

[Bob B.]

My opinion is the 6.2/6.5 makes the most sense for a '67-'72. They can be built into a reliable, economical engine with plenty of power. They fit will few modifications, and have the regular Chevy bell housing bolt pattern. They are about as heavy as a Chevy big block, and will turn fast enough that you usually don't have to change the rear axle gearing. 6.5L's are available brand new cheaper than you will ever find a rebuilt Cummins, and the new 6.5L's have a stronger block and a lot of internal improvements. Now, the others:
Cummins 4B3.9: These are small enough not to require cutting the firewall, but they are tall and the front crossmember might be an issue. GM used these engines in Step-Vans a few years, and there is an adapter to mate a 4B3.9 to a Turbo 400. Good luck finding one. The engine is very reliable, but doesn't make a lot of power, is very noisy and vibrates A LOT. Stock gearing could be a problem, these redline at about 2,300 r.p.m. in many applications.
Cummins 6B5.9: The engine Dodge used. Great diesel, lots of power, pleanty of parts, and a ton of work to get one in a '67-'72. Gearing could be an issue too.
International 6.9L/7.3L/Powerstroke: Probably more trouble then they are worth. Has anyone ever tried this swap?
Cummins 6AT3.4: Not really a Cummins, it was an Onan engine before Cummins bought Onan. Low power, not reliable, getting hard to find parts for. With a long piece of chain, the 6AT3.4 was good in marine applications- AS AN ANCHOR!
That's what I think, feel free to disagree, but I am an ASE certified Master heavy truck tech. with better than 20 years experience.

[JAKES 68GMC]

Originally Posted by Bob B.

Cummins 4B3.9: These are small enough not to require cutting the firewall, but they are tall and the front crossmember might be an issue. GM used these engines in Step-Vans a few years, and there is an adapter to mate a 4B3.9 to a Turbo 400. Good luck finding one. The engine is very reliable, but doesn't make a lot of power, is very noisy and vibrates A LOT. Stock gearing could be a problem, these redline at about 2,300 r.p.m. in many applications.
.

Doesn't make alot of power??? You don't think 300 ft. lbs of torque for a 239 cu. in 4 cylinder is alot of oomph?

[AuggieStyle]

firearmfiend i thought the 5.9 12V WAS NOT computered, but the 24V is computered? please advise as i was going to do the cummings 4bt out of a frito lay truck mated to a 400TH. but was starting to lean to the 5.9 12V because of the fact that it is not electronically controlled.

[70rs/ss]

Also, can't afford adapting a 12-valve 5.9 into my C-10, sorry, not to mention, I really despise electronic controls and doesn't that Dodge have a few?

Supposedly the 12 valve drops right in and 93 is electronic free. so it is a manual pump etc, that is why I chose it, but I won't get it done.

Mike

[70rs/ss]

If you decide cummins, I have a 12 valve in a running driving dually that I want to sell, I bought it for this conversion but will never get to it. LMK

[JAKES 68GMC]

You should PM member TP in Cntl PA. He put a Cummins 3.4AT in a C-30, I'm sure he'd be more than happy to answer your questions.

[Spray-Bomb]

I vote NO to the 6.2 / 6.5td !!!

[72 CustomCamper]

I had a 6.2 in my 72 when I got it from by uncle. He did the conversion so I don't know too much about it. It did run strong, and with the 700R and 4:11 rear I got 22 MPG on the highway. The only reason I removed the diesel is I had to drive it 15 miles through downtown traffic with no belts to find a parts house. i was in a bad part of town and 65 miles from home so I wasn't about to leave it there. I know he used the glow plug timer and had to make a wiring harness that plugs into the factory harness to use the engine. He also had to modify the small block stands to look like big block stands to clear the exhaust manifolds...

Chuck

[earl87gta]

I rilly like the 6.2 and 6.5 I admit its nothing link my d-max but it does what I needed it to do. Im putting a 6.2 in m 68 burb and I will put a turbo on it but im not looking for a lot of power it doesnt tow any thing and but its own waight and i will be geting twice the milage as the 283 thats in it now.

[sleepertruck72]

Just curious as to how hard the new Duramax would be to swap with allison tranny in a 72 c 20 2wd ?would it be a waste of time,money ?

[dieselarmy13]

Originally Posted by sleepertruck72

Just curious as to how hard the new Duramax would be to swap with allison tranny in a 72 c 20 2wd ?would it be a waste of time,money ?

Wouldn't be a waste at all, but look around and check out the prices on these two peices of eqipment. Not to cheap. Lots of electronic thingies all over, too.

[MrBeast]

Originally Posted by sleepertruck72

Just curious as to how hard the new Duramax would be to swap with allison tranny in a 72 c 20 2wd ?would it be a waste of time,money ?

I have looked extensively at doing a Duramax swap. I havn't been able to find an engine for less than 5500.00, It would be a real pain in the ass, because essentially you would have to cut down the factory wiring harness to the bare essentials of what you would need to make the motor run right, and then install it in your truck. Then on top of that you are going to need the Allison transmission. Which is going to cost you another couple of grand. All in all, it is going to cost buku buckaroos and for about the same money, I figured I could build a 12 valve Cummins that would make close to a thousand foot pounds of torque, that is going to be a lot more fun than a stock D-max.

[Mister laugh]

Anyone who says a 12 valver cummins has electronics has no idea what they are talking about, same thing as a 4bt with 2 extra holes in the block (and a bit longer) give em the right fuel pressure and they will run.

[MrBeast]

I work for a heavy equipment company, something I have been very surprised to find out there is just how many machines are equipped with the Cummins 4BT or 6BT engine, they seem to be a damed outstanding power plant. What I do find interesting is that our best mechanic who works on them all day long has one in his truck, and refuses to drive anything else.

According to him the only time he sees them apart in the shop is when some one does something negligent that kills the engine, he swears up and down he has never seen a Cummins fail because of something that Cummins did. His personal truck has something to the tune of 380,000 miles.

From what I can tell about the 12 valve, the metallurgy of the block is very high in Nickel, and thus the block is extremely robust. Also because of the wide spread use of the engine, parts for them are cheap and readily available.

I have a 72 1 ton dually that is going to get a 12 valve hopefully by the end of the summer after I overhaul the engine, and stuff twin turbos on it.

At the same time though, I have a 72 Blazer that is going to most likely get a 6.5 Turbo Diesel.

Really a choice like that is based on application. The engine I am looking at buying the guy wants 800.00 for, I am going to offer him 500, and I might get it for that, and if I am lucky, I will have to do very little to the truck to install it. It is a cheap fix that is going to put my fuel economy through the roof.

I cant decide though because for what I am going to spend stuffing it in, I could make some serious head way on putting the 12 Valve in my Dually. This is a classic case of gear head indecision induced by having too many cool toys.

[69long"n"low]

With the 6.5's and 6.2's are a th400 or 350 strong enough to take the touque and what kind of mods are needed to install one in our trucks....u know fuel and wiring

[MrBeast]

Originally Posted by 69long"n"low

With the 6.5's and 6.2's are a th400 or 350 strong enough to take the touque and what kind of mods are needed to install one in our trucks....u know fuel and wiring

A th400 would be, a 350 might be shaky.

[earl87gta]

they came from the factory with 700r4s so a 350 should work it would be just as strong as the 700r4 would be. On some of the newer 6.5 with more power you may be cutting it close.

[special-K]

I`ve been supporting my family working out of piles of junk since 1986.I`d like to get a DuraMax ever since they came out in`01,but haven`t needed a new truck yet.The`92 I factory ordered is still doing it`s job just fine.The money I`ve saved in fuel could have bought another truck by now,but I still love my junk.It`s not stock,but it`ll run with,if not outrun,newer stock diesels.I don`t have a "chip" to bump up.I don`t think I`ve driven that truck empty for a whole tank of fuel.I did need an injector pump,injectors,and glow-plugs @ 210,000 miles.What a pile of junk.

You know a good old SBC won`t go 100,000 miles w/o head work and usually a cam & lifters.Which is usually peeing in the wind w/o touching the bottom end as well,meaning an overhaul.I`ve never heard any bad comments about those.

[timcos]

My buddies up at www.goldenfuelsystems.com do run down on one of their videos about the different types of diesels.

See the link on their home page... "Click for more info: Chevy/GMC, Dodge, Ford"

Of course for cars are the small VW and larger Mercedes diesels.

In the truck world they really like the 6.9 and 7.3 ford diesels engines. Next is the cummins and of course last and not highly recommended are the duramax's

They get into specifics about each one...beyond me but I get when they say it.

I am looking at adding a 86 for 1 ton because it has the 6.9 in it...they say these are pretty much bulletproof.

Tim

[Rokcrln]

Well one of my long term projects is a 71 crew cab SWB dually diesel and I plan on going with the 12V and pump it up a bit. This truck will be for towing, showing and just plan cruising but at 20++ MPG it should be a great driver as well. I may go ahead and just find a wrecked LWB extended cab dodge and pull the body and use the complete runing gear for my build. As of right now I have the cab started and a set of new alcoa rims but that is it so I have awhile to look for a doner. What I lioke about the 12V's that I have been around is with the right turbo and exhaust they sould just plane bad Ars and like a heavly built semi all in a clasic truck package.
I am also going with the 12V because my Father in-law is a retired bus machenic and built these in his sleep so that part will be easy.

Kevin
LFD Inc.

[munger]

ive seen duramaxs for 2 gs and why not just use a 4l80e or a nv4500 or if you want six spd nv5600 and it would still be less than a allison