VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 More Carter Carb Questions

Hello again. I have continued work on my Carter RJH-08 carb since last post. Ran into a problem and would value advice from this community. This carb was on my '31 coach when I bought it in 1970. It has the shorter accelerator pump which seems to indicate that the pump or maybe the entire carb is from a '29. Does that sound correct? So my carb could be the earlier 125 model or the later 150 model on which someone had replaced the long pump with the earlier shorter model. Any idea how to tell which is the case? When I rotate the throttle shaft on this carb the butterfly will not go to full open position because the accelerator pump piston bottoms out in the cylinder. I could perhaps fix this by bending the lever arm (the piece with holes for summer and winter settings) but would rather fix it right. There appear to be different lever arms for the 125 and 150 carbs. Mine seems to be the 150 version - maybe that is the issue. Any thoughts?

The short accelerator pump is for the early 1929 carburetor.

The 1930-31 150-S carburetor has a different size venturi and choke cone. The standpipe for the 150-S has two vent holes, the earlier version only has one vent hole. The low speed idle tube for the 150-S and the multiple nozzle are different as well. The pump arm, the pump shaft and the pump jet are also different for the 150-S. The metering rod is a different size too.

If you find that you have a 150-S I would replace the accelerator pump assembly with the correct 150-S accelerator pump assembly. You can get the pump cylinder and the plunger from the Filling Station.

If the carburetor turns out to be a 125-S don't use it on your 1931. Find the correct 150-S carburetor instead.

The 125S with the shorter accelerator pump uses a course thread in the carburetor body and on the pump. The later 136S and 150S use a fine threaded pump and body. It is possible to screw in the incorrect pump but will likely leak. That is in addition to the differences already posted by the Dog.

Many thanks gentlemen! Advice much appreciated.

You bet and good luck with your project.