HG engine swap

[Jim W]

Its been quiet a while since I have been on. I did get the Mercedes conversion in the OC-3 running. Its not "finished" but does run and runs good. I was able to locate a brand new drive shaft and modified it to mate with the Mercedes manual trans output. Used some Chevy motor mounts and home made brackets welded to the frame to secure the diesel. New radiator is now mounted out front of the frame using an electric fan. Picked up several track parts from Chris but yet to install them. I take it out and drive it around every so often but right now its tarped over in back of the shop as other projects are using up the space inside. Need to figure out a way to mount the hydraulic pump and rebuild the blade hydraulic system, replace the track support on one side (its an HG set up on one side...) and a few other items as well as turn the tracks around the right way. Will need a custom made hood and grill and still looking for an air cleaner assembly to use on it.

[Doug424]

Why would anyone want to put a 6 cylinder engine in a lil OC-3 ? Engine swapping in itself is hard enough if you have an engine of similar physical size. The extra length of a 6 cylinder is just something you won't need to deal with. I've seen so many of these machines ruined by hanging  some 6 cylinder car engine in them. You need a longer frame, different radiator, sheet metal etc. Most any overhead valve 4 cylinder of equal or greater displacement than the original flathead IX series would be a big improvement.
The International C-123 is rated at 40 Hp, with 101 ft/# torque @ 1200 RPM. Sounds like plenty of power for an OC-3.   
If the bigger engine is going to give you power you don't really need, why bother? Unless you just like to do lots of extra work and like to pour lots of gas in your machine.

[Blake Malkamaki]

Well it depends on what you want to do with your HG/OC-3. If you want to restore it to original show condition, I would keep it original. If it has a loader or dozer and you want to use it to work, I would keep it original, or replace the engine with a similar-sized engine. If you have a plain tractor and originality is not important to you, or you want to build something custom to have fun with, there is no reason not to re-power it with something of your choice.

The HG with Oliver 77 engine we have did not require a frame extension or any harsh modifications. It did require the gas tank be cut in half and the front half replaced by a sheet metal plate, making it flat to allow room for the engine. This cut the capacity in half. It also used an Oliver 70 radiator and grill and plain sheet metal wrap around hood. It was the experimental tractor for developing the OC-6. It would pull a 3-bottom plow.

If one wanted to built a modified fun HG/OC-3 today, a V-8 would probably be a better choice than a six cylinder as it would fit better without gas tank modifications. Though a tractor with a V-8 would not pull a lot more than a stock tractor due to traction, it would have a lot more speed and would be fun to drive in snow, etc., especially if it were a 68" wide machine.

I think there is room for both lines of thought on this one. It's not like these are rare tractors where one would be sacrificing a potential show restoration for a fun modification.

[Doug424]

I still think you would tear it up with the extra hp.  I have worked on lots of these machines and every one of them had one or more of the following: frame to trans  housing bolt failures, cracked frames, cracked castings, sprocket centers broken out, broken teeth on final drive gears etc.  When you see some people run a dozer or loader in dry conditions, it's pretty harsh.  Saying it will spin the tracks doesn't seem an adequate safety feature. They were designed to take a certain amount of torque and hp, and even with the original 26  or so hp engine they tear up, so put 50 60 or more hp in it, what will you get?  In my experience, they might spin tracks in the mud or on wet grass, but against a load a properly counterweighted loader would be destroyed with double the hp.  Sure, you can build a toy to drive around with an oversized engine, but if your going to work it, watch out!!!

Anyone can do whatever they want, just my opinion.  Also,  just stating some facts to give  people who might not have a lot of experience with this sort of thing some background to consider before they destroy their tractor.