The Stovebolt Site Forums The Shop Area The HiPo Shop Diesel engine swaps?

Not sure why I haven’t seen any here yet, but has anyone done a straight six diesel swap in their stovebolt truck? I was thinking it would be a little easier than a SBC, but maybe not᠁.

I believe the six-cylinder diesel weighs significantly more than a SBC. I believe that would be a big factor.

There are a few in the Big Bolts that have made the conversion. Most of the conversions are using 4 cylinder engines due to the weight.

I have inserted a 6bt Cummins engine in my ‘55.2 370 GMC. Doghouse required, space for ‘i’cooler required, Delphi(Saginaw) steering box mounted outside frame on port side. Added late GMC hubs/spindles on existing axle, tires do not stick out past fenders this way. Pictures have appeared here occasionally.

Here is a progress picture. I also notched the #1 crossmember and made a new, lower, #2 crossmember. Raised cab .750”

Ed

I wasn't able to get pictures, but I've seen a quite nice '57 Viking with a 4-53 Detroit Diesel swapped in. It looked factory! The only trouble is the original (also in serious need of an overhaul) T150 axle was geared for a gasser, so not much top speed.

Our taxi in Cuba last month was a 1952 Pontiac with an inline 5 cylinder Mercedes diesel. Engine weight apparently just under 500 pounds.

A 4-53 Detroit Diesel is approximately the same length as a 6bt Cummins.

Ed

If anyone here is interested, I have a GM/Detroit 6.2 Humvee diesel, it's torn down but basically everything from 2 engines only with one block, 2 mechanical injection pumps. The width and length are very close to that of a big block Chevy, same transmission bolt pattern as 4L80. I can list the parts in the " for sale" forum if needed.

I just got a '55.2 5700 I plan on a 6bt/nv4500 swap.

I just put a 6bt in my 55.2 with 47rh.

Ed

UPS used several inline sixes in their box truck delivery vans- - - -292 Chevy, 300 Ford, and an Onan/Cummins inline turbo Diesel that was about the same length and height as the gas engines. It was rated at 120 HP at 3600 RPM, which I confirmed with a dyno run several years ago. It was originally a generator engine that Cummins inherited when they bought out Onan. UPS needed so many of them for their fleet that Cummins couldn't meet the demand, so Big Brown retrofitted the trucks for a different engine and sold the Onan take-out engines for scrap iron prices. I have one of them stashed away for a future project. The engine is somewhat smaller and lighter weight than the ones used in Dodge pickups.
Jerry

Ed please 🙏 tell me more.! What did you do to your front hubs to help with the extra weight If anything?

Steve89, measure accurately, I think you're gonna' find that an inline 6 won't fit in your Low Cab Forward, that is why GM installed only V8's in this model. If the engine in your truck is original it is a 265 V8, the first overhead valve small block Chevy engine.

GMC put 302’s in their LCF trucks, very hard to remove. I have one. Called differently than LCF.

Ed

The hubs are strong enough on a 2 ton axle, springs will probably need to be enhanced.

Ed

Ed, do you know if the cab and radiator are set up on the GMC's with more clearance for different engines? I don't know the dimensions of a Cummins or Detroit inline but I do know that the V8 in my Chevy LCF is pretty close to the radiator and doghouse. I was just cautioning Steve89 to be aware of the confines. I'm happy with mine now with the new 2 speed differential, SM420, 10R/22.5 drive tires, it can stay at 60-62 mph at 3800-4000 rpm.

F370 GMC models (I think this is the GMC equivalent to Chevy LCF) were available with a 270 six cylinder engine, which is about 1.5" longer towards the front than a Chevy six. It was also available with a Pontiac-based V8 which is larger than a SBC, but I don't know by how much.

I have only seen pictures of the GMC's and the hinged hood and fender sections. I could assume that they made accommodations for several engine options. The Chevrolet LCF had only 2 options, the small block 265/283 or a 326/327 Olds or Pontiac.

Cummins 6bt and DD 4-53 require about the same length engine room. Need significant doghouse when replacing gassers

Ed

I've kinda backed off on the idea a bit. The rear ratios being a HI-6.10 and LO-8.10 make the high speed with a cummins 54mph.. haha These trucks were never meant to be speed demons but I'd like 65 if I can get it. Haha.

I posted on one of your other threads about my LCF. The original rear gear in mine was a 7.20:1 single speed, I purchased a 2 speed pig from another Big Bolt member and it made a big improvement. My drivetrain is similar to your's, 283, SM420 4 speed, 2 speed rear. I have 10R-22.5 tires on the rear, the factory spec'd governed speed for these engines was 4000 RPM, mine will do 65 MPH if I bump it to 4100-4200 RPM. If you do larger diameter drive tires you will be able to hit that speed.

I have a 4BT Cummins in my 41 3/4 ton. It fit very well.

I have a 6bt Cummins in my ‘55.2 GMC. Made 8” doghouse. Raised cab .75”, made new lower crossmember under trans. to get engine low enough for exhaust pipe clearance.

Ed

I’ve messed with 6BT Cummins for going on 30 years. Pulled and rebuilt a couple, doubled the hp on many (safely and properly) and love em. Always wanted to do a conversion on a OLD Dodge PW or Chevrolet AD with a Cummings BT4.

However, of late I’m thinking a Isuzu 6bd1 turbo or 4 cylinder version would be better. Why, less weight, higher rpm, great fuel economy and fairly easy to find engines. While I haven’t kept up with the community lately, 10 years ago adaptors for many transmissions were available.

Anyone uptodate on Isuzu diesel’s in AD trucks?

RonR

I saw this at a car show on Sunday.

One of the AD trucks at the Towensend Tennessee show a few weeks ago had a Diesel in it- - - -not sure which one. It was a TIGHT fit under the hood, but the installation was pretty professional-looking.
Jerry

Here's an AD with a 6V Detroit we saw at the ATCA show in Macungie PA in 2010

That must have been a chassis swap, as a 6V Detroit (even the 53) would be HEAVY. I see it's got pretty stout wheels and likely the front suspension as well. And talk about a FULL engine compartment.

The oil budget must be crazy!