Looking for help with designing and building a Mixer for a model Hit & Miss Engine that I am building. The engine is a 1/7th scale of a 7hp Perkins Wind Mill Company. I understand from talking to people who have built this engine per the plans that the original mixer does not work very well. So I have been thinking of using something different for the mixer on this engine.
I like the look of the old Lunkenheimer mixer that was used on some full scale Hit & Miss engines. A scaled down version of this type of mixer is being used on the Red Wing Motor Co. Model engine now being sold by PM Research.
The Lunkenheimer Mixer has a neat way of controlling the fuel entering the engine. Fuel enters the mixer through a one way check valve to one side of the needle valve. Up to this point it is basicly the same as most other mixers. From the other side of the needle valve a fuel passage goes to the seat face of a poppet valve in the troat of the mixer. When this popet valve is closed (by a spring) the fuel passage is closed. As soon as vacuum opens the popet valve, the fuel passage is uncovered and fuel is pulled into the throat of the mixer and into the engine. When the engine stops pulling vacuum, the valve closes shutting off the fuel. The mixture amount is controlled by the adjustment of the needle valve just like 90% of all other mixers.
I am thinking of posibly using a similar setup inside the original Perkins mixer body so it looks original. Or I may just use a straight up draft type mixer to keep it simple. I would be interested in your thoughts on this and also some advise on building a good mixer for this size engine?
Thanks for your help.
1/4 Scale of a 7hp Perkins Hit & Miss.
Bore - 1-1/2"
Govenor - Hit & miss.