vacuum advance question
 

I'm having somewhat of a dilemma with my timing curve. My motor is 461 ci, 9.6:1 comp. ratio, comp cams 288HR cam, torker 2 intake, and holley 830 cfm carb. I'm using the stock distributor w/ the mech. advance limited to 26 deg. On the dyno the motor made most power at 38 total advance (coming in around 3000rpm), which means setting the idle advance to 12 deg BTDC. I have installed a crane adjustable vacuum advance and after screwing w/ it I got it so that it advances a total of 6 crank deg. I'm getting about 9" vacuum at idle and 15" at ~3000 rpm. I adjusted the vac advance diaphragm to just about its lowest setting (it starts to come on at 8" or so). Vac advance is connected to manifold. I would like to run more initial and part throttle advance w/ out changing the total advance.

To do this is it better to run the vac. advance or additionally limit the mech advance? I would like to get the idle advance up to at least 16deg BTDC.