Classic/Antique Car Repair: ELECTRICAL PROBLEM, tilt wheel, painless wire


Question
I have a 51 Chev, with a 1970 Caprice running gear,with a 70 Caprice Tilt wheel,with Painless Wire system,I built this car 10 years ago and untill now everthing was fine.
My problem: when I turn the key the amp gage drops fully and no crank to motor,I replaced the starter,solenode,and battery,it does this on and off ! How ever if I jump the car when this happens it will turn over and start,then it may be ok for a while then this will start all over again.
my friend told me it was the egnition switch ??
Can you help me please ?
Thank You

Answer
Ron
Hea=well it could be the switch but I would clean off all battery terms. and ground connection,all connections. check that the ground is tight also all starter wires should be clean, when you start it see what it is charging at it must be 13 + or no good. ok I would do the switch way last