some questions after changing to propane

[big_al]

I finally got fed up with ethanol gasoline messing up my carb on a self propelled mower, so decided to try propane. I just removed the fuel tank and plugged the carb fuel line. Then added a small propane torch size bottle, drilled a hole in the air filter, and added a regulator and hose from a grill, using the brass part with the small hole poking toward the intake of the engine. It works good, but has to be started with starting fluid. I use the knob on the regulator to control the speed.

At first I lay the bottle down, but the regulator froze so had to mount it upright. Now after 20 minutes or so, the bottom half of the tank is frosted over.

So my questions are, why won't it start off the propane even with the engine hot and why does the propane tank freeze like this? Do I need to change the plug to a different heat or does that matter?

Thanks,
Alan

 

[bertsmobile1]

I finally got fed up with ethanol gasoline messing up my carb on a self propelled mower, so decided to try propane. I just removed the fuel tank and plugged the carb fuel line. Then added a small propane torch size bottle, drilled a hole in the air filter, and added a regulator and hose from a grill, using the brass part with the small hole poking toward the intake of the engine. It works good, but has to be started with starting fluid. I use the knob on the regulator to control the speed.

At first I lay the bottle down, but the regulator froze so had to mount it upright. Now after 20 minutes or so, the bottom half of the tank is frosted over.

So my questions are, why won't it start off the propane even with the engine hot and why does the propane tank freeze like this? Do I need to change the plug to a different heat or does that matter?

Thanks,
Alan

The propane wont start the engine because it an not supply the rich mixture equivalent of having a choke.
The simple venturi type LPG gas vehicle conversions had either an optional high pressure start or petrol start.
Propane is harder to ignite than gas as well so the small spark at pull start speeds might no quite be up to the job.

The bottle freezes because as the liquid converts back into a gas it releases the energy that was used to compress the gas into a liquid in the first place.
It is a little more complicated than that but basically it is phase change entropy .
This is how your fridge/ air con works on a car hot water is used to prevent freezing.
On your mower you could try some thing like running the gas through the core from an old car heater to allow the gas to release the heat into the atmosphere.
You might even make a chiller so you can cool your after mow beer while you are mowing :laughing:

If you decide to persist & why not, see if you can find a flow valve from a car conversion which goes on the vapour supply ( as they like to call the expanded gas ) to the carb which will work better to regulate the speed which is how it is done with cars.
Just one thing, please make sure your regulator has a flash back arrestor on it or your widow will not be happy.

 

[big_al]

Just one thing, please make sure your regulator has a flash back arrestor on it or your widow will not be happy.

Thanks for the reply. I used a hose and regulator for a propane grill with an adapter for the small bottle. I will see if it says anything about a flash back arrester on it.