High performance M or 40, any help?

Since lighter tractors are easier to haul I am looking at building a 40, 420, or M to pull as a modified tractor. Anyone ever stuffed some 4.5" or bigger pistons in one, added a little stroke, and reved one up? Any info would be appreciated.

My dad made a set of high-compression pistons for the M I have. They were originally a dished-top design, and he made them flat-top.

This wasn't for pulling, but because this particular machine was a wreck. One piston had a cracked top, so he opted to machine it out and fabricate a plug to fit. Since he did that to number 1, he had to do it to number 2 as well.

He didn't want to spend any money on the wreck until he at least heard it run again, so everything that was wrecked in the engine had to either be repaired or built new.

It helped that he was a machinist by trade, with his own shop, and also a modfied stock car as well as midget racer. Making hi-performance parts was his main stock in trade, so the little M was a beneficiary.

We never bothered to dyno the poor old thing, but I can tell you that it runs very differently than the stock 420's and 430's (much less a stock M). Instead of the usual 'putt or 'pop' sound, it makes more of a 'crack' sound. It likes 93 octane gasolene as a minimum, and really likes 100 octane racing fuel. Plus, there's that nice odor associated with racing fuel, too. :-)

I never pulled with it, but it sure makes for a fun lawn mower! :-)

Stan

I am mostly curious to see if someone found a big block chevy piston for instance that could be made to work. Something with a piston pin size close enough to bush to the right size and pin location close enough to not push the piston through the head but get around 9:1 compression. The crank shop can handle the balancing and we will send the cam off to be reground. Mostly lookin for ideas on pistons.

Thanks for the input
John