When my 12a drops under about 1500rpm the carb will not release fuel into the front rotor primary causing it to idle very rough and stall often.. if I crank the linkage it will rev up quick with even fuel.. but as it drops down fuel will stop..

I assume something is clogged, but I've never really got into a carb before and wouldn't know where to start.
Any ideas?

 

i had one do that once, i rebuilt the carb, but it turned out that the air pump had come apart and the pieces were jamming the ACV open and causing a HUGE internal vacuum leak. turns out the carb wont meter fuel at low rpms if there is no vacuum.

once the intake leak was fixed (cleaned out the ACV), car ran fine.

 

When the car is just idling, you should not be able to see any fuel going in... I think the issue is on your rear rotor, injecting fuel when it should not be. Or am I confused???

 

Well the weird thing is, its actually not at idle.. because it wont idle at all.. but at 1500 RPM i should see *some* fuel going into the carb.. the rear rotor is fine, but the front side is nothing unless I rev it more... the header also eventually starts to glow red