How do you disconnect the timing advance to set the timing on an '84 Grand Prix 305 4 BBL Chevy automatic?

Unplug the vac advance on the dist.Also there may be a plug on the drivers side of the intake manifold containing 2 wires which when unpluged turns on the ck eng light.Sometimes the balancer outter ring slips and you have to replace the balancer to set the timing.