Farmall H differences

I have two H"s, one is a 42 and the other a 50. The 42 was originally set up to run Kerosene, it has the dual tank, used to have shutters, and had the exhaust diverter (long rusted away). My grandpa bought the 42 new. The question I have is a difference in power. The 42 has significantly more than the 50 even though they are the "same" tractor. Now, on the 42, my dad told me once that the head was changed when grandpa no longer wanted to run kerosene because the kero head was a lower compression head. On the head itself is stamped a large letter "H" which either my dad told me or I heard somewhere (or think I remembered!) that means this is a high compression head. Does anyone know how I would find out? Nothing life or death, just curious to know why the difference in power between the two. I have rebuilt both engines and the 42 got flattop pistons, the 50 got thinwall sleeve/hightop pistons and still the 42 has more power.

The other difference between these two is how cold blooded they are. The 42 is AWFUL, the 50 is not. If its winter, the 42 has to have the choke nursed for a long time - even in the summer you have to watch the choke when its cold. The 50 will usually start even in the winter with litte to no choke unless it gets down in the teens.

Thanks!

Norm

Other than the comp ratio of heads could be different, the ignition systems have several different spark advances. Magneto was basically 35 degrees , batt ign could be 40 ,30, 25, 22, or 16 so that would be one place I would check out. Some minor changes were made in carburetors, main jet size, air bleed size or blocked air bleed on some power packs. Valve length will tell you which head you have but of course you can't tell that without disassambly. You could check the head numbers under valve cover. A worn out govenor will make a gutless wonder also along with the proper adjustment of govenor internal linkage.

Pete's idea of timing is important. When a timing light is used, the full speed timing needs to be in the 25 degree range, Find the exact number in a manual. The compression numbers will also help assess performance. 125 is about normal for a gasoline stock H. Checking both will be valuable. Jim

I have a 1951 farmall h it has a single front wheel and a large propane tank where the gas tank should be. i have no idea what i have can someone help me??

Start a new post.
It is a propane conversion, Not stock.
Put a picture on here and we can help. Jim