I am working on bringing back to life a neglected 85 pickup. 22r federal emissions, and have run into a carb/timing problem.
1. It is running rich at idle (black smoke, gas smell). Started with adjusting mixture screw, its 4 turns out, but even if I screw it in all the way in there is no change in idle. But I can adjust the idle speed to specs with the idle speed screw. I am guessing fuel is getting in but not through idle circuit? Oh, fuel level is middle of the window. All hoses in good shape and hopefully correctly attached per the FSM.
2. Thought I would check the timing, set to 0 degrees with advance hoses plugged, reattach advance hoses, no change in timing (should advance to 12). Vac advance in distributor works if I apply about 10 inches of pressure, but am only getting 5 inches from the vac line from the carb base. 17 inches at the manifold.

I am guessing the low vacuum and bad idle circuit are somehow related, vacuum leak? Anyone here got a suggestion before I go shopping for a carb rebuild kit? Wish I could take some of the emissions spaghetti off, would be a lot easier to work on.

 

Is the choke opening up all the way ? Are the secondaries sticking open?

 

Yep, choke comes off just fine, secondaries are closed at idle. Pulled the vacuum hose off the aap and no gas inside the hose, and no vacuum once warmed up, so its not the diaphragm, but I suppose it could be leaking internally. Obviously gas is getting in from somewhere. If I pull off a vacuum hose from the base of the carb the engine revs up to 2000 rpm. Guess its time to tear the carb off and see whats inside. I checked another distributor, and it too seemed to need about 10 in of vacuum to open the advance (I am only getting 5), anyone know what the vacuum should be at the fuel cut port at idle?

 

I know with my weber they say if you can't get the motor to stumble while adjusting the idle mixture then it is most likely a vacuum leak.

When you have the air cleaner off did you also block off the MC valve and all the other hoses you have to undo?

Another place you can get a vacuum leak that might be over looked is the oil pan gasket via the PCV valve. if you remove the pcv and block it does your idle go down?

Also check here for the best info on the net about the AISIN carb. : http://www.bluebassdesign.com/boonin/carb_faq/