Farmall Super M Propane

[Lightner]

Morning,
I recently purchased a Farmall Super M Propane powered tractor.
Was wondering if Farmall built the propane powered tractors in their factory or did they send the to be modified.
Anyone have any idea how many Super M Propane were built.
Thanks,
Billy

 

[DeltaRed]

AFAIK,The Super M was the first factory equiped propane tractor.I dont think records were kept on how many propane tractors were built. But not many I would guess.Earlier H/M were later equiped after they left the factory.AFAIK,Minneapolis Moline offered the first propane tractor. I think it was 1941,but not sure.

 

[Russ from MN]

There is a nice looking propane powered MM for sale just S of Kelliher MN now! The way it was explained to me before WW2 there was a surplus of propane in the summer, so it was cheap. During WW2 the cracking process was developed in the refiners so they could make what was needed, not just whatever came out of the tower, so that was the end of propane popularity. My uncle what a big fan of propane power, and he was a bus driver and mechanic for his school district. He talked them int buying some propane busses, but with the extreme cold weather it didn't work out so well. Now, with the problems with the DEF systems, maybe it wasn't so bad!

 

[Charlie M]

Of all the propane tractors I have seen I think MM did the best job of designing them so they didn't look so bloated with that propane tank.

 

[da.bees]

If a tractor is expected to be used more hours than would be necessary for shows and parades it's arguably worth buying one originally on propane then converting to gasoline if gasoline is your preference. Hard seats that withstand unleaded gas being the reason. If engine is to get total rebuild ,it wouldn't matter if seats were hard or not since they could be installed when head rebuilt.

 

[m16ty]

If a tractor is expected to be used more hours than would be necessary for shows and parades it's arguably worth buying one originally on propane then converting to gasoline if gasoline is your preference. Hard seats that withstand unleaded gas being the reason. If engine is to get total rebuild ,it wouldn't matter if seats were hard or not since they could be installed when head rebuilt.

I don't know about the M, but some propane models had higher compression than the gas models. To change it to gas you may have to either change the head or run high octane gas.

If you have access to propane, I'd rather have a propane tractor than a gas tractor. Propane doesn't go bad and doesn't gum up a carb like gas will. I used to have a old propane tractor, that thing could sit in the barn for a couple years, put a hot battery on it and it would fire up like you just ran it the day before.

 

[used red MN]

I don't know about the M, but some propane models had higher compression than the gas models. To change it to gas you may have to either change the head or run high octane gas.

If you have access to propane, I'd rather have a propane tractor than a gas tractor. Propane doesn't go bad and doesn't gum up a carb like gas will. I used to have a old propane tractor, that thing could sit in the barn for a couple years, put a hot battery on it and it would fire up like you just ran it the day before.

I am about 95% sure all the Super Ms and SMTA LP models were sent to an outside vendor to convert/install the propane fuel system. I suspect that the engines were assembled at the factory with the parts to yield the higher compression ratio to run with LP. If you search around a bit you can probably find some previous YT posts on this. The “100” series (300, 400) were the first ones to roll out of the factory turn key to burn LPG.
As far as compression, the LP engines don’t even have a high enough compression to worry about them not being able to run on pump gas. Factory Super M LP CR was 6.75:1 vs 5.9:1 for gasoline models. I think current 87 octane gas will work fine in none computer controlled engines up to 8:1 CRs with cast iron heads and rough “as cast” combustion chambers.

 

[Charlie M]

I'm confused - why do pulling guys want LP heads for their tractors if they don't add significant compression from a regular gas motor? Is there something else about those heads that makes them more desirable?

 

[John M]

I don't know about the M, but some propane models had higher compression than the gas models. To change it to gas you may have to either change the head or run high octane gas.

If you have access to propane, I'd rather have a propane tractor than a gas tractor. Propane doesn't go bad and doesn't gum up a carb like gas will. I used to have a old propane tractor, that thing could sit in the barn for a couple years, put a hot battery on it and it would fire up like you just ran it the day before.

One of mine has had a propane head and intake on it since, oh 76 or 77, and doesnt require anything extra.

 

[m16ty]

I am about 95% sure all the Super Ms and SMTA LP models were sent to an outside vendor to convert/install the propane fuel system. I suspect that the engines were assembled at the factory with the parts to yield the higher compression ratio to run with LP. If you search around a bit you can probably find some previous YT posts on this. The “100” series (300, 400) were the first ones to roll out of the factory turn key to burn LPG.
As far as compression, the LP engines don’t even have a high enough compression to worry about them not being able to run on pump gas. Factory Super M LP CR was 6.75:1 vs 5.9:1 for gasoline models. I think current 87 octane gas will work fine in none computer controlled engines up to 8:1 CRs with cast iron heads and rough “as cast” combustion chambers.

I don’t know what the ratio of the farmall LP heads, but LP will run fine on gas model ratios, it just won’t have as much power. LP likes a ratio of 10.5 to 11:1 to get the most power out of it. You’re going to have to run at least 93 octane gas (if not higher) at those ratios.