Cam break in lube should already be on the cam, plus you'll have a good break-in oil (VR-1 would be an example). Top two reasons people have to shut a car off during cam break-in is overheating or leaks. If that happens, by all means shut the car off and fix it, then restart and continue.
- Make SURE your car is timed to fire off right away. Yes, you can be sure with the timing and fuel supply.
- Make sure you are full of coolant. IF you have a thermostat, make sure you drilled a small hole so the coolant can fill without having a air-lock
- Use a KNOWN-GOOD carb. Do NOT break in your cam with anything else (unless F.I.)
- Start with the timing advanced.
- soon as it starts, get the rpm's up to about 2000 and set the idle at that rpm. Then drift it back and forth between 2000-2800 rpms for about 20 minutes.
- Really helps to have another set of hands and eyes to help watch or go get something.
- Some have a box fan pointed at the radiator in the front.
Good luck. :)