Author Topic: Allman model gas engine (Read 9119 times)

parallelmotion · « **on:** September 06, 2025, 03:36:54 pm »

I'm really a hot air and steam engine guy but couldn't pass this one up. It's a 1/3 scale model of a 3/4 hp inverted engine made in 1898. This new (to me) model was the 3rd example (no. 1003) sold as a finished engine by Debolt Machine in the mid-1980s, so it's now about 40 years old. It hadn't been run in decades so a little cleaning of the fuel mixer was required prior to this trial run.

Raphael · « **Reply #1 on:** September 06, 2025, 03:59:53 pm »

Bonjour,

My first passion is steam, and I also like Hit & Miss engines very much. This one is particularly exceptional in my opinion, I envy you

Little question, do I see a radiator ? is it actually one? If so, how does the water circulate? I don't see any pump and the cylinder seems quite thin...

parallelmotion · « **Reply #2 on:** September 06, 2025, 04:02:56 pm »

Thank you Raphael. Yes, that is a cast iron radiator. As I understand it the model has a cavity for water cooling but not a full water jacket. A friend says his will run for hours without water (no load).

Stoker · « **Reply #3 on:** September 06, 2025, 04:56:02 pm »

That really is quite special!

I would guess that a thermal syphon would develop between the cylinder walls and the radiator. Warm water rises in the cylinder and transfers over to the upper end of the radiator, where the water then cools, and "falls" to the bottom of the radiator from which it transfers back to the bottom of the cylinder?!?!

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Author Topic: Allman model gas engine (Read 9119 times)

parallelmotion

Allman model gas engine

Raphael

Re: Allman model gas engine

parallelmotion

Re: Allman model gas engine

Stoker

Re: Allman model gas engine