Massey Harris 50 High Altitude

[agjim]

I have a MH 50 with factory LPG. There is a plate on the engine block stating this tractor should not be operated at altitudes below 5000 ft. What is the reason for this restriction and what else can you tell me about this tractor?

 

[lrswet1100]

Going to say it probably started out as hi altitude gas tractor that someone converted to propane. The serial number tag on the dash does it have a H or B in the serial number ?

 

[Masseyharrisnut]

I’m guessing that it is a tractor that was built for export to maybe Brazil. Again just guessing without more info. As far as the warning about altitude the fuel would just need to be adjusted to operate at the altitude you are at.

 

[agjim]

Going to say it probably started out as hi altitude gas tractor that someone converted to propane. The serial number tag on the dash does it have a H or B in the serial number ?

The tractor is about 40 miles away from me now but I'll get the numbers and letters that's on the plate when I get back to it. Thanks.
Jim

 

[Masseyharrisnut]

Going to say it probably started out as hi altitude gas tractor that someone converted to propane. The serial number tag on the dash does it have a H or B in the serial number ?

I looked in some of my Massey books and can’t find anything about a propane model 50. Doesn’t mean they didn’t do it though. I think lrswet1100 is right about it being a conversion. Pictures of the propane set up would help. But I think the altitude problem can still be overcome with simple adjustments.

 

[ptfarmer]

The "high altitude" engine just had a higher compression ratio so it can make the same power at higher altitude. The compression ratio is about 8.0:1 for the high, 6.0:1 for the low (maybe about 20-30 psi between the two when measured at the same altitude) todays "cheap" gas/fuel is better knock/detonation resistant (which is the main problem) than the "cheap" gas/fuel was back then, as long as you keep up with the engine tune it's not that big of a deal (todays gas engines have 9.0:1 and higher compression ratios)

 

[Masseyharrisnut]

That’s really good info to have. I always thought that they changed the timing and carb settings/jets to get the performance at altitude. I’ve got a couple tractors that are high altitude. We are at around 3500 feet where I’m at. Thanks for the knowledge.

 

[agjim]

I have a picture of the SN plate if that helps identify my tractor. Thanks

 

[ptfarmer]

SHGM- S=standard width, G=gas, H=high altitude, M=dual clutch, 510328=1956 year model

 

[X]

Just my two cents, weren't factory LP tractors built with higher than regular gas models compression? If this was not a factory LP tractor, but is a "high altitude" model would the compression be just about right at a lower altitude for LP?