battery drain when vette sits more than 2 days

I had the same problem with my 72.  I changed where it was grounded and it fixed the problem.

If I remember correctly, it was to the engine block

My 76 has two ground cables, first from the battery to the frame then a second from the frame to the right side motor mount bolt. It was this way when I bought the car. You can always remove the ground cable starting at the battery and clean it with a wire brush then move to every other place the ground cables connect since most ground problems are corrosion related, also do the same to the positive battery connection, if you haven't already done so. 

I would be inclined to have the battery tested since you may have a weak cell, even if the battery is new, also look for things that can or do pull power all the time even if very small could drain a battery that isn't strong enough.

My car came with a fairly new battery but the reserve capacity would only last half an hour if I was lucky, I replaced it with a larger size and higher reserve capacity and now I can work with the doors open and not have to recharge the battery. I switched from the standard 75 series battery to a 78 series and I'm glad I did.

Good luck and keep us posted with your results. 

Eric

Had this problem on my 77. Cleaned the ground cable then replaced the battery. Noticed that the positive cable was not original and replaced that. Problem solved but if the car sits a really long time it still ewill drain down some. Ibought a battery tender and past year ,no matter how long it sits will start on first turn fully charged.

Gentlemen, you are probably correct when you say it is likely a corroded ground connection,
but don't overlook some the aftermarket stereo's and clocks. A lot of the recent years stereo's have a constant voltage drain to keep their internal "clock" and memory for station settings. I replaced the stereo in my "other" car a while back, and it hasn't drained the battery since!