Hey guys, what pistons are these? (M)

Using a bent end scribe, I've determined that the dome is about .250 tall, also it has no gaps across the top of the dome, it's continuous. The quench side of the piston is flat. GeorgeKy had sent me a photo of some Firecraters and they're not like that. Also found some other photos by searching the archives and still no match. Judging by the photos, the domes don't seem to be as tall as the M&W turbo dome or some of the new aftermarket ones I've looked at. The dome does seem to be wider though.

The tractor has the X1B suffix, which makes it originally a 5000ft. altitude setup. Would a dealer have paid any attention to that when ordering a replacement motor? Or perhaps would it have been a replacement _block_ with someone building the rest from parts and putting in higher comp. pistons? Could all replacement motor in the later years have come with higher compression?

If you can find that chart it might give some idea of possible compression ratios. I won't be able to get a picture up as I don't want to pull down a running motor.

What little I've run it, it seems to run good except for the governor hunting. It runs strong. The biggest problem for the tractor is transmission issues. I think it's in the shifting linkage. Right now I have first and reverse. It seems like it wants to go into two gears at once for the other speeds.

To my knowledge, however there are far more experienced folks on the board in this area than I, but I believe that Fire Craters were an overhaul (performance upgrade item) made for IH by "Perfect Circle" as an accessory add on only. I have a chart here some place that I think would tell me. I don't think any H or M blocks came from the factory with Fire-Craters in them, not even the 8,000 ft or propane models.

Others have confirmed for me that the original "high compression" pistons were even made out of cast iron & not alum--and am sure they were a flat stepped only design.

Not sure what pistons were avl in the 300 thru 450 high compression models from the factory.