[r67cat]

Doug, I do believe that the Duraspark vac. can is adjustable. I have an after market Echlin VC 945 can on my distributor. It is adjustable as I believe your is with an allen wrench (5/32 if memory serves me). I adjusted mine to begin to advance at about 6 in. of vac. It is all in at 14 In. With my cam/heads/carb. set up I pull about 10 in. of vac. from the manifold port at idle. This will get for me about 11 1/2 degrees of additional advance at idle. Full advance at 14 in. is 14 degrees. My set up is 12 degrees static, 36 degrees total, all in at 2800 rpm.(no vac) After the vac is engaged my idle is 23 1/2 degrees at a steady 850-900 rpm. You will notice a much quieter exhaust note at idle and at cruise, better throttle response and less heat in the side pipes. Also you will need to adjust your idle speed back down with the additional advance. This will help cure any run on issues you may have had with the MSD set up and no vacuum advance. Keep us posted as you make the conversion. Rick