Gas aditive for 45 HG 42?

[Bill Hunter]

My neighbor was over today to see how I was  getting along with the tractor. He asked if there was any problem using unleaded gass. Told him I didn't realy know but knew some people that would. So what is do you guy's think?

[Blake Malkamaki]

Bill, there should be no problem using unleaded gas in your tractor. Most of these engines were designed before there was any leaded gasoline. Most can run on kerosene if desired.

Some of had concern about running older engines, that were made to use leaded gas, on unleaded gas. This is true of some of the high performance engines of the 50s, 60s, and 70s that develope valve seat where due to no lead in the fuel. Most of these engines are designed for high speed and therefore have very strong valve springs that allow the valves to close fast.

Our tractor engines do not have valve springs that are near as strong as these high performance car engines do, therefore there's very little need to worry valve seat where.

One concern I do have, however, with the modern unleaded fuel available today, is I don't think it has as high of vapor pressure as the older fuel did. Most of the vehicles on the road today are fuel injected and have electric pumps that force-feed the fuel from the tank into the fuel system. Therefore the fuel does not need to perform under a vacuum - as is created by a mechanical fuel pump - so the suppliers do not have to design the fuel for this situation.

I have experienced vapor locking conditions with modern unleaded fuel in farm tractors on hot days. I've had the fuel boil in the carburetors and fuel lines on gravity fed systems, such as my Farmall Super M. It usually happens while baling hay or something else in the hot summer.

Like our Cletracs, the Super M was disigned to run on low octane fuel - probably around 60 or 70 octane in the time it was built. Or even kerosene, which has a lower octane. But today's regular unleaded with 87 octane will not run good. Now it doesn't detonate inside the engine, but it does vapor lock in the carb and lines. I think it's a vapor pressure problem.

Higher octane fuel does seem to help. An additive that enhances the vapor pressure may also help.

Blake

[Bill Hunter]

Blake my HG has been set up with a low presure electric fuel pump,2-3.5 lbs. will this help with the new fuels?

[Blake Malkamaki]

It probably will. I presume it's just pulling out of the bottom of the tank, so it's not lifting the fuel at all. Should work fine.

I wonder why they went with a fuel pump? Maybe for going up very steep hills?