fairbanks morse garden tractor

[CGBusch]

Last winter, I started to build a 2hp throttle governed FMZ garden tractor. (I don't want this to be a butt-buggy, but rather a true working tractor.) The frame is homemade and is constructed with a large variety of parts. It runs, drives, stops. I had a problem though, the floatless carb/mixer would starve on hills.

This is the carb bowl I made out of the IH 20-40? brass carb bowl. This will bolt beneath the mixer on the frame. I tested it with water and it works. I'll make new gaskets and will test it with rubbing alcohol (since its less viscous).

The tank on the side is a hill climbing anti-starve tank, since the gas tank behind the crank guard its still possible to starve the carb on extremely steep inclines. The outlet is mounted flush, while the inlet is a longer nipple that goes halfway into the can so the inlet is effectively in the middle.

I noticed however with my testing the mini tank only partially fills. Since there isn't an air gulp the mini-tank won't fill all the way? Will it eventually fill?
If it eventually fills, will there be a siphon effect even though the input is at the top?
Do I need to install a air gulp check valve? Would a check valve just leak?
Should just I install a 2ndary line from the top of the mini-tank to the top of the main tank? I think that would fix it...

--
Chris

[Harvey Teal]

Chris, the engine should produce enough suction to pull the fuel directly from a small tank located near the mixer, if appropriate check valves are used and the packing gland around the mixture screw is tight. Why are you placing the fuel tank behind the engine?

[CGBusch]

I want it to look good too. I have an old McCormic Deering secondary gas tank (6in by 12 in cylinder fuel tank) and it looks best mounting behind the crank and 10in above the original ground level of the engine. The original tank was below the engine and would starve going up hills and required the mixer to be adjusted when the tank ran low (which the original users must have had to monkey with too).

[Harvey Teal]

So you're doing gravity feed?

[Elden DuRand]

What I did with my ZC-52 engine on my Hoyt-Clagwell butt-buggy (AND working tractor) was to put a stiffer spring (about twice as stiff - "guess, cut and try" mode was used in the selection) in the inlet air choke plate. This gives more suction to draw fuel from the tank mounted beneath the engine.

I went one step further. I tapped the hole in the cast iron plate 1/4-20 where the original choke spring rod was removed. I made new spring rod from 1/4" bar stock and threaded the inside (throttle plate) end about two turns and jammed a nut on it to hold the spring. I then threaded the outside end of the rod long enough to screw into the choke plate with generous room for a lock nut. I slotted the outside end of the rod for a screwdriver. Now I can adjust the tension on the choke spring.

It's a balancing act between the needle valve and the choke tension. The needle valve adjusts the high speed (power) mixture and the choke spring tension adjusts the idle mixture. It takes a bit of juggling to make it work right but, once done, it requires very little twiddling with the needle between full and nearly empty tank and moderate hills are not a problem. (my tank is a little over 4" deep with the feed from a 2" deeper "well" in the center.

That's my experience, consult your doctor or take two aspirin and call me in the morning.

Take care - Elden
http://home.cybertron.com/~edurand

[CGBusch]

Yep, I'm doing gravity feed.

[CGBusch]

I installed my IH carb bowl beneath the mixer of my FMZ on my garden tractor. At first it didn't work. I took it apart again and I think the float was stuck. I tested and retested and everything looked good. I drove it over to get water and went to the garden to pull a cultivator. I was pulling it ez in the plowing gear (a very low gear on my peerless trans), I ran to get weight and noticed the engine quit... Is it out of gas? nope. go to restart it, where's the intake valve?



The valve keeper clip must of busted! It sucked in the valve and bent it. The head and looks like they only got a minor nick, so I'll order new parts and hope to get working with it again. I plan on installing a sleeve hitch, then the tractor will be very useful.