Hi wanted to know ,have 69 Cuda, 318 auto, with mild cam, headers, Holley carb, people using a Pertronix system Ignitor II dist and coil, what spark plugs are you using , the gap they are set at, and engine modifications. Trying to get a handle on my problem of no start, have gotten to the point where I have the 318 running, now able to give it some gas [throttle] and the engine now revs up, but got a backfire out of carb. [ before giving it throttle the engine did nothing], I have the Pertronix dist and Flame Thrower II coil , running NGK gr4gp platinum plugs gapped at .35, other person on this site felt should regap to .40-.45 because of the hi output coil [ Flame Thrower II 45,000 volts]. Back story, I bought a slightly used Pertronix II dist. D141710, was told by the person he only used it to break in his engine on line from Evil Bay. Istalled the dist, with my old Speedmaster high output coil, I may have damaged the Pertronix Igniter II unit inside, since could not get it to barely run, ran really really rough, if try to give it throttle it did nothing and would die. Have since replaced the Igniter II unit in the dist. have been able to start car now, runs a little better, removed the spark plugs all 8 where carboned up, I think because they where not firing, cleaned them up and as stated I have NGK gaped at .35, started car was running a lot better, was able to give it throttle, so now it would rev up and it smoothed out , but when I let the throttle go, got a back fire out the carb. so I think I need to advanced the timing, also replacing the plugs will try Champion rn12yc before trying to do any more work and adjustments [timing] . Have been battling with this problem since early this year!