Set timing, hei mod

The usual reason an engine likes more timing at idle is it has a long-er duration cam in it than stock. Could this be the case?
[1] To check HEI p/up polarity: one of the Ch p/up wires should be black. This wire goes to the 'G' terminal [ small terminal ] on the HEI module.
[2] Module must be grounded through mounting ferrules to work.
[3] You can use ANY 12v coil, but if it is designed for points or comes with a bal res, the bal rest MUST be used.
[4] To get the highest spark energy from the module, use an E core coil like the MSD 8207.