When I pull the vacuum line off the distributor and cap it there isn't and idle increase or decrease when hooking the hose back up. I'm pretty sure the engine should rev higher when the hose is reattached. This this mean the vacuum advance is toast, also if this is the case what are some possible issues when running. Stock 350, the carb does have vacuum coming from it. Thanks Jaye
Should give more information about car. Year, 2 or 4 barrel, stock distributer or not. Stock carb or not. It doesn’t necessarily change idle as your not Accelerating . Stock ,68-69 may have vacuum to it. But should not change idle rpm much if tuned well. Put a timing light on it and check the timing with and without the vacuum line on. check the vacuum line for vacuum. If there’s no vacuum, there will be no advance.
If you hook the vacuum advance back up to a manifold source, the idle should increase, AND you will see the timing move with a light. If you test it with a ported source, nothing will happen as there is very little if any vacuum at closed throttle. You can also test the canister with a vacuum pump. If the VA canister is bad, it will not hold vacuum.