So I have a 1954 bel air 235 sedan powerglide, and are having a bit of a problem with starting. I just recently took off the starter, and rebuildt it to clean it and to see if possibly it would help the problem. This morning I checked the voltage of the battery with a DMM, it was at 6.07V. When I went to start the car I would hear just one click (louder click) from the starter and nothing else. Tried again 4 more times or so to turn the car on and same thing would happen but the clicks from the starter would get quieter each time. After the last time, I checked the voltage again at the battery and it was down to 5.8-5.7V roughly. Any ideas on what I should do to fix this. Or should I try and put another 6v batt. in parallel to the other batt. and have a switch to turn off one of the batteries after start-up, if so how would I go about doing that? Thank for any help.

 

Check the condition of both battery cables for looseness and corrosion at both ends not just at the battery. Is your battery fully charged and do a load test on the battery.

 

Battery cables, and or solenoid

 

I third attention to the Cables. Remove, wire brush, replace if necessary n tighten snugly.
You should be holding 6.3 vdc minimum on a resting (24 hr) voltage test. If you don't drive it enough to maintain that, you should get a Battery Maintainer, which will keep the Cells from sulfacting.
I guess you could add a supplemental battery, but, I don't think that's your problem.
Focus on the connections or starter.