- Joined
- Apr 22, 2013
- Messages
- 3
I amcompleting a Paul Breisch “Associated” hit and miss gasoline engine and havemodified several features of the design. This note describes the muffler andcarburetor.
The motivation for these changes was for ease of machining inboth cases and to simplify the design and improve performance of the carburetor.Figure1 shows the original design and Figure 2 shows the modified design.
The semicircular exit ports in the top of the muffler werereplaced by round holes, which enabled them to be drilled rather than milled.
The original carburetor design used threaded fittings forthe fuel supply, the jet in the Venturi and the needle valve. I threaded thecross arm fpr the needle valve and am using plastic tubing for the fuel, whichslips on the cross arm. The position of the fuel injection orifice is positionclose to the center of the Venturi as the velocity of the air flow near thewalls is slower than in the center due to friction with the walls. Figure 3shows the completed components and Figure 4 shows the entrance to the Venturi.
The motivation for these changes was for ease of machining inboth cases and to simplify the design and improve performance of the carburetor.Figure1 shows the original design and Figure 2 shows the modified design.
The semicircular exit ports in the top of the muffler werereplaced by round holes, which enabled them to be drilled rather than milled.
The original carburetor design used threaded fittings forthe fuel supply, the jet in the Venturi and the needle valve. I threaded thecross arm fpr the needle valve and am using plastic tubing for the fuel, whichslips on the cross arm. The position of the fuel injection orifice is positionclose to the center of the Venturi as the velocity of the air flow near thewalls is slower than in the center due to friction with the walls. Figure 3shows the completed components and Figure 4 shows the entrance to the Venturi.