Intermittent ignition help

Datsun78 said
'69 Barracuda convertible, 318, auto trans, Pertronix ignition module. Have intermittent problem where car won't start. Have lights, horn, etc, but no click or starter engagement. Shifting trans, repeating turning key, tightened positive battery cable has no effect. If left for a few days or weeks, will start up and run fine, until happens again. Replaced neutral safety switch and connector, but no change. No discernible pattern to issue, other than has always happened in the garage(fortunately).

Any guidance to what to check?

Thanks!

Mark

Sounds like you have a no-crank problem, not a no-start problem. When it happens, can you get the engine to crank by triggering the starter relay under the hood? (careful that the car is in park doing this!) If not, it could be the relay, starter, starter solenoid, a bad battery cable connection, or the power wire to the relay. If it will crank from triggering the relay, it could be a bulkhead connection problem, ignition switch, neutral safety switch, or wiring between those items.