VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 carburetor adjustment

Hello,

The idle adjusting screw of my carburetor is open to the maximum, about 2 turn. Despite that the spark plugs become black after some miles, thus I guess the air and fuel mixture is too rich ?
Any solution ?

The engine is a 1930 one but the carburetor is an early 1929 (with the short pump)

Thank you for your help,

Edmond

It is difficult to diagnose a carburetor problem without actually test running and/or taking it apart and checking the parts used.

The fact that it is running with the idle adjusting screw out 2 turns is a strong indication that there are serious problems with the carburetor. Typically used RJH-08 carburetors need to have the idle adjusting screw fully seated or only out a partial turn. If the throttle shaft is replaced and the passage bushed the new specification of ~ 1 1/2 turns is possible.

If you measure the low speed jet, multi-jet (main jet) and metering rod bottom end I should be able to determine if they are the correct parts. If the jets are original Carter parts they should have numbers stamped into the threaded bases that can be used to identify them.

I have rebuilt hundreds Carter RJH-08 carburetors in the past 20 years and can likely rebuild yours.