Larry:
So you know I only work on newer stuff but I have 2 ideas.
1. Do a blowdown test on #6 to see if the leakage is thru the valves or rings/piston.
2. Get a quart bottle and hook it up to your carb IV-style in place of vac tank. That will at least tell you about the idle issue.
Cheers Dave
I saw this a few minutes after he posted it. Just luck. Boy, I had to think really hard. I would have 3 coupes, 36, 38, and 40. But I would be single again.
Make sure the cutout voltage is adjusted correctly. Use the procedures in the 1940 Shop Manual to check out VR settings. It doesn't take long to do.
Cheers, Dave
This is the one I use. 300 amp. I mount them on the inner fender wall and use #00 cable. Only adds about 2 feet of cable, but my batteries are under hood.
Menards
https://www.menards.com/main/electrical/light-switches-dimmers-outlets/light-switches/gardner-bender-reg-battery-shutoff-switch/gsw-bt/p-1642874300255863-c-6324.htm?exp=false
You see these for sale NOS on ebay from time to time. I got a nice Niehoff one a few years ago. I will try to find the stock number.
How is the coil failing? Just no workee?
Cheers Dave