So I buy this 63 Avanti! Car o' my dreams. Starts 9 times out of 10. 10th try nothing. Arc the solenoid? It starts, for another 9 times, then same again! I get an arcing sound like a spark arc, but once it starts, smoooth as silk! Ideas? Yes I put in a new solenoid, and yes, same problem!!
Congrats on owning a modern cl***ic. The ignition switches Stude used were junk. Replace the switch. jack vines
Starting with battery, clean every terminal all the way up the cables. Lock washer all the 5/16" studs after cleaning, and examine terminals on cables. (!) Also the small wires: look for green acidic corrosion, replace any terminal where it shows up. (replace that wire if practical) Be thorough, and as PackardV8 states: Ignition and lamp switches Stude used were inferior. (known fact in the trade)
Don't forget the ground cable and its connections It takes a good clean system on both sides to get a complete circuit. The juice needs to get back to the battery. Intermittent problems can be very hard to cure.
I know it's a bear to do but remove the starter and either test it yourself or have it tested. It could have a dead bar on the comutator. Makes an arcing sound and has intermittant open circuit. Dave.