If hooking up the Vcan changed your timing then your T-port sync. is off; Your throttle is too far open. Start by plumbing in your PCV. The PCV acts as an IdleAirBypass for our warmed up engines.
I also had the main manifold vacuum port wide open ( took the hose to the brake booster off to change the dizzy and forgot to put it back on till I hooked up the vacuum advance to the carb. )
I have been meaning to get the reducing fitting so I can connect the PCV. One of those things I always forget to buy when at the store!