choke takes too long to open?

[nola mike]

Just finished a Carb rebuild (2 bbl mercarb). Running great except that it starts hard cold. Actually, it starts right away, but then runs rough until the choke opens. If I manually open the choke it runs fine. Is this a choke problem (takes maybe a minute to open), a problem with the rebuild, or a mixture setting problem. Thought I set the mixture correctly, but maybe I should lean it out?

 

[dollarten]

Re: choke takes too long to open?

I am having the same problem right now on a 4.3 like a did have on a 120 . Both with electric choke . There is a device in the carb called the "choke pull off " It is supposed to open the choke plate about quarter inch -or+ so the engine will run properly upon start up until the electric choke continues it's opening cycle . There is a vacuum passage inside the carb that is blocked and not allowing vacuum to partiality open the choke . Or , it could be the choke linkage is not adjusted properly I just never got around to fixing mine so I let the engine run at slow idle until the choke opens further . and do not give it any throttle until the engine is warmed a bit or , until the choke starts to open

 

[cr2k]

Re: choke takes too long to open?

Back off the adjustment on the choke.

 

[dollarten]

Re: choke takes too long to open?

The choke pull off should still override any choke thermostat spring setting . If it is backed off too far , then it will not close . Or, if it is warm weather dial the choke all the way open and run without the choke by working the throttle a few times to make the accelerator pump shoot some gas in the carb Another term that is is used is called the vacuum break instead of choke pull off . Google it and it will explain .