Stop in for a cup of coffee

Mattax said

Agree they do - its the electronics. Its the dirty secret. Some are faster some are slower but even nowadays only a few designs are setup to compensate in the electronics. Most factory race efforts compensated in the distributor.

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Another little secret is that almost all of the 5 pin stock replacements are actually a 4 pin internally and the 5th pin is a dummy. That makes the second part of the dual ballast useless and can confuse the hell out of someone trying to solve an ignition problem. Because they are 4 pin internally, they also carry the ignition advance controls that the original 5 pin didn’t.