Hi Folks,
I have noticed that some of the commercial suppliers (Anton Monahan, and Hemmens) offer engines with a water pump run directly from the crank shaft.
The water pump has its valves set in a horizontal attitude.
In all the model mags I have read over the years water pumps were geared down by 4 or 5 to 1 and the valve boxes were always set inlet on the bottom and outlet directly above so the gravity assists the seating.
Given the amount of turbulence inside pump valve boxes, would the valves set horizontally seat quickly enough to avoid cavitation.
When I finished making my most recent pump I tried it using a varispeed drill set at about 100 rpm and held it so that the valves boxes were horizontal. Although it pumped, it was rather feeble. When I turned it so that the valves were vertical the output improved, markedly.
Is there something special about the pumps used on the suppliers pumps above or am I missing something. If anyone uses one of these pumps I would be most interested in your experience.
All the best, Fred Graham