Reply To: Carberator Adjustment for a 1930 Model A

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Hi Syd, the carb on the ’30 cars only has an idle screw for adjustment. The mainjets are fixed jets. Unless the mainjets have been changed, then usually the orginal jets are too lean for today’s fuels mixed with alcohol. If I remember correctly, the jets are stamped on the outside with the jet size, maybe you can read this number with a mirror and post it here, and someone with a similar car/engine can compare their jetsize to your’s.

The only other ‘adjustment’ would be the float level, if the fuel level is high, it will run a bit richer.

What indications or symptoms do you have that lead you to think it’s running rich? Heavy black smoke out the exhaust? Fouled spark plugs? Or??

If your points have closed up [usually from the rubbing block wearing down], this will retard the spark, which can give some symptoms similar to a too-rich mixture. Have you tried to run the spark advance lever near full advance? Have you checked the distributor to see if the automatic centrifugal advance is working correctly? A non-functioning centrifugal advance will make the car sluggish and not burn all the fuel because the spark is too late.

That’s all that I can think of.

Greg Long