Others will probably have a more direct idea, but I know I've run a bunch of irrigation motors in the past - 454's, 350's, Ford 534 V8's, MM HD800's etc.One time I had the local repair shop overhaul a MM 800 inline 6 to run on natural gas. The engine ran great, but the exhaust manifold was so exceptionally hot, I could barely get close to it to pour oil in it. You could see it glowing from a half mile away at night. Like I said, I've run a bunch of engines and this one was off-the-scale hot. After a couple of months of 24x7 operation, the engine thrashed (galded piston) - the repair place said it was my fault, so I disgustedly started tearing it down to repair it myself. The oil inside had been baked into asphalt that I had to chip off with a chisel. After I got a piston out, I carefully was checking the rings, when I realized they were installed UPSIDE DOWN! I pulled all the pistons - covered in tarry asphalt, and they all had been installed wrong. I took them over to the repair shop and the owner scrambled from one book to another, the instructions that came with the rings, etc, and finally agreed they were installed incorrectly. They wound up rebuilding the engine for me for free and it was fine after that (and we are still friends). I can't explain why upside down rings would make an engine act like that - and I'm not even sure that it was cause and effect. But that was my experience. I wonder if your engine might have a piston or two with the same condition. Howard
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