The Stovebolt Site Forums The Shop Area Engine Shop Carb mpg ?

I take it you have the Roch. model B. These are fun to play with because they are so easy to take the air horn off & make changes. Start with the main metering jet. Look at the number stamped in it. Get one with about 2 numbers less. Make shure the float level is correct. Make shure the hole in the base of the carb has vacuum passage to the manifold. If the engine hesetates when it is cold without using the choke & runs good after it is warmed up you have about the right mixture. I know this is not like haveing an exhaust analyser but most of us don,t have acsess to $50,000 worth of equipment. Make shure the heat risor valve is working. Make shure the vacuum advance is working. Try advancing the timing a few degrees. If the engine pings on accel. move it back. After the engine is warm turn the idle mixture screw in slowly till the engine starts slowing down. Then turn it back just enough to speed it back up. This ought to help.