I have a Pontiac 400 in a 1976 Nova(Ya I know), we have installed everything and I just can't seem to get the timing dialed in right without it popping through the exhaust or back fire through the carb. I am at my whits end on this. We lined up the dots at 12 and have the rotor pointing at #1. Any help Please. Its a 1976 400 with Edlebrock heads a hyd roller cam Performer intake with headers. heads are the 87CC.