FARMALL 504 GAS ENGINE SWAP

My approach with a 504 gasser, would be find an engine from a Farmall 300 or 350. Those C-153 weren't much from the day they were new, supposed to be rated around 45 hp, yet a 300 or 350 would give them one hell of a run. Couple of days ago I posted that out of 16 Farmalls, I got one lemon, yes it was the 504 gasser. I've talked with other owners the experienced the same.

Fresh out of an engine rebuild at 1,500 hours I put my 504 in the field pulling a No.60, 3x16 plow. After about 1 hour I switched to 300 with close to 12,500 hours, probably 3,000 away from it's most recent rebuild. The 300 pulled the plow much better than the 504. That was 1975 and the 504 went down the road, traded on a new tractor, and yes I got $3,000. more than I would have for the 300, simply because the 504 had 3 point hitch.

A working 504 with the D-188 diesel or a more reliable gas engine is still a very usable tractor, with IPTO, 3point hitch and forward operators platform. The 300 or 350 engine will be a direct bolt up at the rear. You will probably have to modify, front engine mounts, fan shroud assembly, breather, radiator hoses, etc. Shouldn't be too bad as engine will be close in size.

I think Hal pretty well nailed the reason; C-123, C-135 and C-153 are all the same block, just bored larger. The C-169 and C-175 are the same block but much heavier than the smaller block, lot more steel in them, basically the main reason why they are a better engine for 35 to 45 hp.