<VV> Fitch Engine

[Kenneth Schifftner]

Gang:

I recently helped a club member get their 140 hp engine running...similar symptoms as Michael described.  The driver's side primary would not respond to mixture adjustments or idle speed changes.  I made sure the secondaries were fully closed...they were.  The engine was knocking and rocking. The engine had recently been rebuilt but not the carburetors.

 The driver's side primary carburetor choke would not open....right side OK.  Thinking the choke needed adjustment, I tried to adjust the choke on the driver's side to no avail.  Then club member Steve Calandra said to check the exhaust temp...cold on that side (engine has dual exhaust).  I removed the idle mixture screw completely.  Noticed that when the engine was running, there was no hiss at the idle mixture screw port.  I tried to spray carb cleaner into the port but the liquid shot back at me, even with the engine running.  I then held my hand over the carburetor inlet and blipped the throttle....on about the 5th or 6th try....finally hiss.  I sprayed in more cleaner,,,,,this time the cleaner (mostly) went in.  The choke started to open...I then replaced the idle mixture screw and got idle mixture control back as well as idle speed. As that suddenly heated, the choke opened. I then balanced the primaries using the Dwyer gauge. Smooth running engine.  Something must have blocked the idle mixture pathways in the carburetor.