Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I'd have thought that the intermittent firing pattern of the hit and miss engine might lead to issues of butane building up in the intake system, though careful adjustment might smooth that out. You would also need to be careful about the stuff leaking into the air, say if you were distracted by a phone call or a visitor while running, which it is much more likely to do than liquid fuels. There is an explosive risk obviously with gas escaping.

Personally, i think the way these small engines handle ordinary petrol is very convenient and sort of 'correct' to type - they are models of the once very common farm engines after all which the vast majority of worked that way. I know some oilfield engines of the period burned well gas, so you could justify that if you wanted to replicate that type of usage.