Question for all the experienced tuners out there: I've been working on idle tuning my 750 speed demon. Why am I finding fuel in my vacuum gauge line when I disconnect it from the ported vacuum after I've "finished" setting the idle mixture. Other burning questions I'm wondering about: Fuel seems to stay in the float bowls without evaporating but I've noticed that my inlet hose is dry after the car has sat for a few days. Does fuel normally flow back to the tank while the engine/mechanical fuel pump is off or do I have a leak? Also, I'm on a quest to improve emissions because the fumes are bad enough that I push my Skylark out of the garage to start it or it permiates the house. I've attributed the fumes to idle mixture, lack of catalytic converters, or overlap on the camshaft (TA 413). I've upgraded to Capacitive Discharge ignition and tried for better idle tuning a few times now. Is it just part of life or could I be doing something better?
First, you don't connect a vacuum gauge up to ported vacuum. You connect it to manifold vacuum. If you are seeing any vacuum in the ported connection, it's usually because the throttle is open too much, and if that is the case, you aren't idling on the idle system of the carburetor, your activating the main feeds. It happens a lot with Q-jets, but Holley's are not immune to it. It sounds like you are running way too rich. One reason for this could be insufficient initial timing. Try advancing the timing at idle, and closing the throttle adjustment. If you find that cleans up your idle, you need to have your distributor re curved so that you don't over advance at higher RPM.
