d16a6 / d15b vtec mini me ignition timing can't be set

I've completed the vtec head swap on my d16a7 (d16a6 block) with a Jim d15b vtec head and d16a7 cam gear. I've set cam timing just fine using the timing marks but when it comes to ignition timing i can't get enough advance on the dizzy. It gets to about 12 degrees before its maxed out
can anyone provide insight into this issue? Thanks.
can anyone provide insight into this issue? Thanks.