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Mod | | | Forums66 Topics128,095 Posts1,056,075 Members48,433 | | Most Online14,466 Apr 26th, 2026 | | AD Chevy Trucks Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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on the Internet for over 30 years! and not clogged down with Ads! Again, thanks! | | | | Joined: Oct 2008 Posts: 8 New Guy | | New Guy Joined: Oct 2008 Posts: 8 | Can anybody help me with information on doing this type of conversion .I own a 1946 coe , I pulled out the old engine and wanted to replace the engine with a 235ci in line 6 from a 1955 bellair since they seem to be the same type of engine. Now a mechanic told me the most i can get up to with that engine is 40mph and if i have anything that i'm transporting i won't be moving. Would anybody agree ? So I saw a few coe with a mid engine mount and hope to put a chevy 350 in it. | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Will you be changing the transmission and/or rear-end? It's not the 235 engine that primarily limits the speed when you have a stock drive train.
Does "Mid engine mount" mean putting the engine where it was originally - under the cab?
| | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | What are your trying to accomplish? I have been 60 mph with a 55 model 235 in a 4,400 lb truck, it's not the engine at that point but the gearing that limits speed, faster gears would allow me to go faster, to a point.. However, if I were to throw in another 4,000 lb the engine would then be lacking power, and slower gears would be good. If you put the engine behind the cab.. then your COE turns into a CIFOE (Cab In Front Of Engine)  Grigg | | | | | Joined: Oct 2003 Posts: 5,152 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | Maximum possible speed really is a function of horsepower and with original type motors these trucks will never be speed demons. But run the math on the transmission and rear axle ratios and you'll see pretty quickly that it takes more than a motor swap to move one of these things fast.
I think your mechanic might be a little pessimistic, but only a little. On the other hand how fast do you really want to go with 60 year old brakes suspension and steering?
I'd like to know how you intend to use the truck, kind of roads, kind of speeds, kind of loads, length of trips, all that kind of stuff before I try to comment on what the right modifications would be.
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more... It's true. I really don't do anything but browse the Internet looking for trouble... | | | | | Joined: Oct 2008 Posts: 8 New Guy | | New Guy Joined: Oct 2008 Posts: 8 | well first I don't want my truck to be some speed demon but I would like to be able to junmp on the expressways and go a little over 60mph . I also would like to be able to transport one or two motorcycles. Will a inline 6 235ci engine give me this if I put a good trans? They suggested to install a chevy 350 and I've seen some coe with a mid mount where the engine is installed in back of the cab. What do you think . | | | | | Joined: Oct 2003 Posts: 5,152 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | Two motorcycles. 350 pounds each, or 1,000 pounds each?
If 1,000 pounds each you are talking 2,000 pounds plus whatever support stuff you carry, so you're talking about an 8- to 10,000 pound gross vehicle weight.
Can you get a 235 or maybe a 261 (truck version of the 235) or a GMC 302 to move it at over 60 mph? Probably, though it might take some work, including finding the right combination of rear gears, transmission and tires.
If running an original type motor or preserving the originality of the truck is important to you, I say give it a try. You might be happy with the results.
But on the other hand, if you really want a V-8 go for it. If you are hiring a shop to do this, make sure you look at similar work they have done before. If you are doing it yourself try to look at a few others have done first.
And plan on upgrading the brakes just as much as you upgrade the ability to go.
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more... It's true. I really don't do anything but browse the Internet looking for trouble... | | | | | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | People amaze me, do they think that in 1946 everything was hauled by train, boat, or perhaps horse and wagon. My best friend drove a brand new 46 COE tractor with which he made two trips a week hauling 45,000 lbs of steel from Pennsylvania to Texas each trip. There were through two different mountain ranges it had to pull through and once clear of them and with the two speed rear he could run 50mph on good roads (no interstates then). Yes, there were Whites, Macks, Diamond T's, Reos, etc., but there also were many stovebolts and flatheads making those hauls.
Evan
| | | | | Joined: Feb 2003 Posts: 1,377 'Bolter | | 'Bolter Joined: Feb 2003 Posts: 1,377 | I was looking at a cabover at the turkey run that had the mid mount motor and there was no way I could use it as a truck since the motor was only about 6 inches off the ground,it was on a late model chassis and the cab mounted as low as it would go but a mid mount motor will cause some problems with hauling as they usually stick up through the bed some or are too low to the ground and cant be used off smooth ground. Jeff | | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | I saw a AD COE with a Dodge Cummins mounted behind the cab, he had a bed around it, and a cover something like you would expect for an inboard boat engine, a lump sort of with doors made of aluminum sheet with louvers punched in it, it looked ok, but nothing special, and just about made the bed useless. As for having the engine behind the cab I think he did about as good as he could for having a useful and good looking truck, but it still looked weird and out of place..
What's wrong with an engine under the cab?
Grigg | | | | | Joined: Oct 2003 Posts: 5,152 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | Putting the engine under the cab, in the stock location, means you have all the noise and heat and limits how low you can mount the cab.
I've seen a couple where the engine is mounted under the seats, which allows lowering the cab further, but you still have the heat and noise.
I'm not advocating the mid-engine approach, just repeating what I've been told when I asked the same questions.
I'm still gearing up and collecting parts to do two COE projects. On one I think I'll copy the under the seat approach, covering the back of the motor with an old looking in bed tool box.
On the other I'm now considering rear mounting the motor. This would be for the project I've called my COE Suburban Cargo, and mounting the motor all the way at the back using Toronado or El Dorado or GMC motorhome parts might be the best compromise to achieve what I want.
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more... It's true. I really don't do anything but browse the Internet looking for trouble... | | | | | Joined: Jul 2015 Posts: 4 New Guy | | New Guy Joined: Jul 2015 Posts: 4 | I'd like to see your ideas! Just about to pick up two '41 COE's and want to build one for a car hauler. Any thoughts much appreciates. | | |
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