I’m restoring a mid-70s Hydra-Mac 8c. It weighs 3200lbs and came with an Onan NHC rated at 25hp. This is the same as an International 4130. I was looking at a Kohler Command 730cc, but wanted to run this past you all in case there are any better suggestions or if more power is recommended. Smallenginewarehouse.com doesn’t offer a kit for this machine but a suggests a Vangaurd 23hp for similar sized machines. The shaft coupler accepts a 1 7/16” shaft. This machine was well kept and is all gear driven, no chains. I’ll be fabricating the riser plate and linkages so that’s not a big deal. Thanks in advance.
Why not keep using the NHC? All the parts are available and repowering will always have hassles.
I thought about rebuilding it but decided I want a newer unit. The rebuild kit was around 800 bucks and I never even liked it when it was running anyway. I'd mess with the points and it would run OK for a few months, then the temperature would change 10 degrees and it would be back to having what seemed like 50% power again even with a carb rebuild and new plugs and going through the valves. I can't even look at the darn thing anymore without getting ticked off. I had a buddy give me an old JD 90 loader engine which was a slightly newer NHC and I had the same issues with it! I want something new that I don't have to mess with I've got my hands full with other projects and need this thing reliable.
Id go with the Kohler Either way should be a pretty easy and well worth it repower
Thermoking (Isuzu) or Carrier (Kubota) reefer engine, IF it will FIT.
Well I work on generators which have both the Onan engine and the Kohler engine in abundance and I like the Kohler engine better. It is OHV where the Onan is flathead and much more modern but being a V-twin I figured it might be hard to make it fit. It also has hydraulic lifters. If you want somebody who knows, HG Makelim in San Francisco used to be the Kohler engine experts, they might be able to help. I don't think a Vanguard is a bad engine but I think Kohler is better.
If you can find one, in a horizontal config, I'd put a kohler 28 EFI, like my dixie chopper has. IMHO, best, most trouble free gas motor I have ever had. You might need to find a whole machine, to get the motor, with all the wiring harness, to do it. It would help to have a good DC dealer, who has all the tech experience, and diagnostic tools to do the transplant.
I actually did a re power in a hydra Mac just like yours, I used a thermoking from a reefer just as Delmer suggested. I had to have a coupler machined to connect the crank to the hydro unit. I also had to Fab up motor mounts, a radiator setup, and a bell housing. The thermoking fit in the chassis, I did have to move the rear door back though. It’s not too hard with the right tools. Good luck!
I went with the Kohler CH730. Can't afford the EFI version but the torque ratings are nearly identical and I am more familiar with the carbed units and honestly haven't had any major issues with them over the last 20 years. Ordered from OPEengines and it should be in this Friday or Saturday.