In my 1972 Malibu with a 307 and a year old 63 amp alternator, my volts bounce between 12 and 14. Not constantly, but once ever few miles it will drop to 12 volts as if the alternator cuts out. Then after I rev it a couple of times to about 3500 rpms it comes back. It hapens at stops and while driving. I idle at about 800 rpms.

brad,sounds like a voltage regulator problem.
I would start there, could also be a short somewhere in the charging system. 67rat member #199

I agree with the Rat. That's the first sign of your voltage regulator going bad. Next, your lights will start to flicker. Change it before it goes really bad. If you still have the external voltage regulator, its located on the radiator support behind the driver's side headlight. Its a small box with a 4-wire wire harness plugged into the bottom of it. Refer to Tech Reference #14 for more info. Good luck!

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Jeremy J. Bennett
72 Chevelle
Team Chevelle #298

Do you have a ground strap between the engine and the body? Check this first before you spend money on parts you don't need. I see lots of Chevelles at shows that the ground straps are missing, never reinstalled after an engine swap or repairs. My 69 SS396 has a wire that runs from the negative cable at the battery to the right front fender. My 69 Malibu small block has two braided straps that fasten to the firewall from the valve covers.

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Team Chevelle Gold #33
ACES Member #02913
Chevelle Club of Michigan

Unless you have a problem keeping your battery at full charge, I would not get excited about this.
If I am not mistaken, your 72 still has the external mechanical regulator. I'm going to tell you a secret that most people do not know today. (All the mechanical regulators did this type of bouncing around) I drove these cars when they were new and they did it, and mine still do it today.
If you have the external regulator and your battery stays at full charge, leave it alone. If you are running the internal solid state regulator and the voltage jumps around, fix it.
I'll tell you another secret. The old mechanical regulators were far more reliable than the newer solid state ones, so "upgrading" is a mistake.