i have a 67 chevy 350 with hei.wont turnover or crank at a cold startup.battery and starter both new. will only start if i let it sit for 20min. after attempting to start(all electric accessories work while i try to startup)
If this vehicle has an automatic transmission, check the neutral safety switch. The starting circuit on 67 vehicles are pretty simple. See if you have 12 volts on the start terminal of the solenoid. If the voltage is there check for voltage at the starter motor downstream of the solenoid. These measurements should steer you to correct path to find the problem.
Post back if you need more specifics.