Purchased a 64 impala last fall, and have only run it a few times (currently being restored). I put a new battery in it after I got it, and ran it for 5-10 minutes about every week up until a few months ago. I disconnected the negative terminal on the battery each time I was finished. About a month ago I reinstalled the instrument bezel (with clock), and left the battery cables attached. Battery is now dead! Soooo, I swapped out with another battery, and the car fires right up, and I let it run for about a half hour. After I shut it down and went to restart it, the battery was really weak. I am assuming the alternator is not charging properly and probably needs replaced. It seems odd otherwise for two batteries to discharge so quickly. What does everyone think? FYI, the distributor was changed to an HEI unit by the previous owner. The car cannot be driven to a garage, and I don't have a multimeter at this time, but I cannot think of anything else. Thanks in advance for your responses!!

Check the charging system. Should have 14-14.5 volts at the battery with the car running at a fast idle. If you have battery voltage or less, its not charging. If you left the battery cables attached and the battery went dead you probabley have a drain. The drain can also be caused by the charging system. To test for the drain, disconnect any clocks and radio with memory, with the car off and everything turned off. disconnect a battery cable and connect a test light inline between the cable and the battery, with a drain the light will be lit. You need to make the light go out to find the drain. Disconnect things one at a time till the light goes out. First disconnect the alternator and voltage regulator plug, then fuses at the fuse box.

Thanks for the response, but I have a question... Even if I have a drain, why would a new battery be going dead when the car was running for half an hour? Also, I have the factory clock, isn't that going to cause a small drain?

Thanks for the response, but I have a question... Even if I have a drain, why would a new battery be going dead when the car was running for half an hour?
Its no different then leaving you lights on. With the car running, maybe alternator shorted, just drains the battery. Just because it was a new battery doesn't mean it was fully charged either.

=64chevyAlso, I have the factory clock, isn't that going to cause a small drain?
You need to disconnect this before testing for a drain. I am not familiar with 64's but it should be on a fused circuit, just pull the fuse.

My 64 would eat voltage regulators, and either over charge the battery or not charge it at all. It sounds like the alternator or regulator is not working. That is why after letting it run for half an hour the battery was dead it was using the battery to keep the car running.

Did you have to change the alternator with HEI, if so how many amps for a 67 396 BB, no options. Thanks

You can buy a analog multimeter at radio shack that will tell you all you need to know for about $20. I have one and its invaluable. I use it around the house too.

Did you have to change the alternator with HEI, if so how many amps for a 67 396 BB, no options. Thanks
Changing the alternator is not required to do a HEI conversion. HEi's only pull a little more power than points, not even enough to worry about. As long as your current charging system works, you will be fine.

for a 67 chevelle 396 ,with no power options, what is the correct amp alternator. Thanks