I have a 1976 Sears ST12 that I am looking at repowering. The original Tecumseh 12HP is getting long in the tooth. It has intermittent ignition issues, smokes pretty bad and burns a noticeable amount of oil. Given that the Tecumseh parts can be somewhat difficult to come by, I'm looking at repowering the tractor with a new engine. The rest of the tractor works great.
I've looked at a lot of single cylinder engines around the 12HP size and they all look to be too long to keep the original grill in place. Mostly due to the cylinder laying down at an angle vs straight up like the Tecumseh. The twin cylinder V engines are a bit more compact in that respect. After looking at a lot of V engines, it looks like the Subaru EH65 would be a good fit. Everything appears to be in the correct orientation for clearance and access. The only thing I'm not sure about is if the clutch pulley mechanism will clear the new engine. I ran across one example of a EH64 installed in the same tractor and it looked like a great fit.
Does anyone have any constructive input on doing a swap like this? I realize the hood will have to be replace or cut to allow the larger muffler to fit.
The EH65 is more engine that I need, but it has all the right specifications and readily available parts that would seemingly make the sway somewhat easy to accomplish. I looked at Honda V engines and they appear to be a little more compact, but the documentation I found on them was a little lacking compared to the Subaru engines.