Running a petrol engine on Propane

[John Wood]

Hi all. Bear with me as I'm new to forums and don't know what I'm doing!
I have a half-scale Economy - Hit & Miss, open crank engine from The Engineers Emporium which I would like to run off Propane gas. Can someone advise how I should go about this please?
I have a Propane 3061 adjustable regulator fitted to my Sievert braizing torch and also a standard fixed regulator on a Propane barbecue - are either of these of use?
I presume the petrol carburettor is not used but what does one use as a throttle?
Any information would be gratefully received

Thanks - John

[mutley]

Hi John
Have a chat with Adrian at the Engineers Emporium as i think he runs his demonstraotrs of propane at the shows.

[John Wood]

Many thanks - will do if I can get hold of him!!

[paul]

May 13, 2008 13:14:22 GMT John Wood said:

... and don't know what I'm doing!

I wouldn't worry, you're not alone Some people on here claim to know what they're doing and others claim that they know what other people are doing.

Sorry I don't know anything about your question although I do like the smell of propane. Or is it butane? See, I told you you weren't alone

Welcome aboard by the way!

[albert]

Hello John
Many years ago I built a Wyvern 40cc open crank engine which ran on either gas or petrol. Either fuel was piped direct to the carburettor,to a fuel jet after the throttle valve. It ran on butane with the gas pressure almost nil.This was a published designe in I think Model Engineer.
Bye Abert.

[jackrae]

Some 45 years ago my father had a Fergie petrol/paraffin tractor that I converted to run on butane. At the time I was a snotty nose appentice that would try crazy ideas to see what would work - fortunately I had a sympathetic father who encouraged inovation.

If you want your engine to run at constant speed then all you need is a needle valve to control the gas feed rate into the air intake manifold. It'll take a bit of fiddling to get it to run smoothly -to get the correct gas-to-air ratio.

However if you want it to cater for variable speed or load things get a little more complicated since you'll need to alter the gas rate.

The basic difference between a petrol carburettor and a gas one is that the former uses the air intake velocity to "suck" petrol through a proportioning jet, whilst the latter has to use the same vacuum to open a gas valve.

For the tractor I made a vacuum sensor valve which opened the gas supply in proportion to the manifold intake pressure. A bit hit and miss but it worked.

So, have a go, have fun and try and keep your eye-brows from getting singed off

[jasonb]

Do you really need a throttle on a hit & miss engine?

The speed is set by adjusting the governor, if it gets too fast then the engine will "miss" if it slows or is put under load then it will "hit"

Both the Wyvern and Centaur have carbs that can take liquid fuel or gas and Engineers emporium sell a carb that works with gas.

My Hit and miss runs of petrol but I may try one of the bubble carbs as detailed in latest ME as it can flood a bit too easy

Jason

[John Wood]

Well folks, what a super response from all of you, I didn't know forums could be so interesting and helpful. I have taken note of all your comments and valuable information and will have a go over the next few days, I'll let you know how I get on.

As a newcomer I have all sorts of questions to ask so, much encouraged, I will post them here as I go along. I am learning all the time so hope to be able to answer some of your questions as well.

Thanks again John