Model Airplane Carb on a Hit & Miss ?

[chads]

Can a 2-stoke model airplane engine carburetor be used on a small Hit & Miss engine.

Just wondering if anyone has tried it...

 

[jct842]

or a henry ford model? john

 

[kf2qd]

If the fuel level is not too low, those are vacuum carbs with no float so the fuel will tend to flow back to the tank when the intake valve is not opening. When the intake valve starts opening again it will take a bit before any fuel gets to the carb. And depending on the volume of air you might be marginal on the vacuum at low speeds.

 

[Noitoen]

Aeroplane model engines pressurize the fuel tank with a tap in the muffler. I don't think it will function properly otherwise.

 

[chads]

Looking at the plans for my carb, they dont seem to be much different than a model airplane carb. Maybe I can use the needle and seat from an old airplane carb I have laying around and adapt it to the one I will make. Perhaps a small check valve will be in order to keep the fuel flow correct as well.

 

[seagar]

The work fine on a 4 stroke model aero engine even without preasurising the tank.( I have used many in r/c/planes.

Ian.

 

[gbritnell]

I use model airplane carbs or model airplane style carbs on all my engines. They do not need to be pressurized to work. My fuel tanks have the top of the tank just below the needle valve level on the carb. The engines will pull all of the fuel out of the tank even when it gets down to the bottom. So the answer is yes. The only problem with using them is they are calibrated for alcohol/methane fuel which means for gasoline use they are a little touchy about adjustments but otherwise work perfectly.
gbritnell

 

[cl350rr]

why would you need an adjustable carburettor on a hit and miss engine. I thought the design was based on a constant fuel/air mixture to the engine governed by the opening of valves.

Randel

 

[Metal Butcher]

Chads, the 'Webster' IC engine uses a small off the shelf carb. They are very simple to make, vs buying carbs that are expensive.

Randal, a hit-n- miss engine needs a carburator with an adjustment needle. The needle is Not used like a throttle to set the speed. The needle it used to adjust the flow of fuel, to get the proper air to fuel mixture (ratio). Not enough fuel and the engine stall, to much fuel and the engine stalls.

The engine speed is controlled by the exhaust valve lock out mechanism, which is controlled by centrifugal governor weights, which are controlled by variable spring tension.

Speed controlled by speed. :idea:

-MB

 

[cl350rr]

yeah, that's what I was trying to say.

 

[chads]

I have a large collection of model airplane engines as I fly RC. I do have a few old control line engines laying around, no throttle. Maybe I will use one of them.

 

[jpeter]

How big is the hit n miss. Model engine carbs are often pretty big bore for a hit and miss that only turns about 600 rpm. If the carb is too big the engine will have a hard doing a hit after a period of missing.

 

[Metal Butcher]

I have a large collection of model airplane engines as I fly RC. I do have a few old control line engines laying around, no throttle. Maybe I will use one of them.

Sounds real good chads, if you have some why not give them a try. You could make a close fitting adapter out of aluminum. And install them using a silicone gasket compound, this will allow you to take them off with out doing any damage while you test them.

-MB