Carb question

Hello fellow hudsonites,

I recently managed to wake up my 54 Super Wasp and made a good little ride with it and everything runs great, minus a rough idle, especially when the transmission is on drive. 

While taking a visual inspection prior to check the ignition timing, I found out that 
I may not need to set it.

As seen on the picture ( sorry for the picture being sideway), Hudson did put a guide for the distributor setting and it seems to be already set as it should be, wich is 9 degrees according to the shop manual, yet the engine does have a rough idle. Then I did remember something regarding the carbs: both of the carbs are WA1-2013S wich are used for Hudson Jets and Super Jets while the original carbs that I should have on the Super Wasp are WA1-2114S.

My curious question is this; Could the wrong carb number can give a rough idle, even when everything is properly set? If not, where should I give attention to smooth the idle for the time being? I already have the idea to search for a pair of the proper carbs to set during the next winter.

Any thoughs on this curiosity ?


  • tigermoth
    tigermoth Expert Adviser
    edited April 2022
    what color smoke comes out of the exhaust at idle? How do clean spark  plugs look after the car idles for a bit?

    regards, Tom
  • Max162
    Max162 Member
    edited April 2022
    tigermoth said:
    what color smoke comes out of the exhaust at idle? How do clean spark  plugs look after the car idles for a bit?

    regards, Tom
    To answer your question Tom, I think the it has a normal smoke color, but I can attest that there is a "bit" of carbon that came out of the pipe. So I assume that the excess of carbon might be a symptom to the rough idle.

    I did wip the throttle for a short time to have this result and was already giving signs of a smoother idle on drive gear.
  • lostmind
    lostmind Expert Adviser
    Compression even in all cylinders?
  • Jon B
    Jon B Administrator
    The problem could lie in a bad spark plug or spark plug wire for one cylinder, couldn't it?    Hmmm.... seems like a simple way to test THAT would be to short out each spark plug with the engine running.  Each plug you shorted would cause the engine to run rougher, EXCEPT the plug with the bad spark plug.  If indeed a spark plug were the culprit, there would be no change in roughness when you shorted that particular plug (because it's already running roughly).  

    (That was off the top of my head, so is not guaranteed to be an authorized Hudson test.)
  • Note that there is a bolt on the underside of the distributor for timing adjustment as well (in fact with more range).  The scale on the top side is not absolute, but it is sure convenient.
  • StepUp
    StepUp Member
    edited May 2022
    To answer your question ---I don't believe using a different model carb would cause a rough idle (however, the different metering rods and jets might impact acceleration). Vacuum leak(s) can also cause rough idles.