Reply to "Help? intermittant won't crank over?"

...All the Symptoms point directly to the Ignition SWITCH!! IMO
The contacts are 'Burned' and are barely making a Weak-intermittent contact.
Four(4)componants are NOT getting full voltage, full time.
1. The Distributor (weather Points or Electronic Brain...doesn't matter).
2. The Coil.
3. The Starter Solenoid.
4. The Starter MOTOR, itself.

I would test for this by...First Disconnecting The Battery Grounding Cable and Fully CHARGE THE BATTERY UP!! Then Bypass the Ignition Switch, by 'jumping' 12 Volts to the Distributor, and then jump the Solenoid AT the Solenoid.
If Your Battery is Older than 3-4 Years, it is 'on it's way out'! Monitor the Voltage at the Battery, using a Voltmeter/Multimeter....AT the Battery DURING CRANKING. You may also check Cranking Voltage AT the Starter Motor. If the voltage drops below 9 Volts (AT the Battery) During Cranking, the Battery is Not capable of doing the job.

The Engine should crank over and fire right up.

If the engine does not crank, check the battery cables and the Connections! If battery does not deliver Voltage, Replace Battery.
If the engine cranks and does Not FIRE-UP, Check for Spark AT THE SPARK PLUG, And check for Fuel at the Carb Throat when the Accelerator Pump is Actuated.

This should give You a starting point to work from and a Direction to Search in!

Let us know what You find and we'll work on the problem from there!

Good-Luck!
Marlin