Ignitor installation mandates checking ignition timing along with dwell angle with a tach-dwell meter. Ignition timing for sixes is 6 degrees BTDC with manual transmission and 12 degrees BTDC for automatics. The best advice we can offer is starting at factory specifications, then perform a road test with moderate acceleration. Gradually advance the base ignition timing one degree at a time, then road test and check the timing again. If pinging (spark knock) occurs under acceleration, retard the ignition timing one degree at a time. Be sure to check vacuum advance for proper operation.