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6 volt system question

824 views 4 replies 4 participants last post by  vwnutt 
#1 ·
I have an original 39 Pontiac coupe with original 6 volt stuff. I bought a new battery from NAPA, but they said they had little demand for them so had to order from their warehouse to get it. I have no 6 volt experience, but I know the weak voltage is why everyone swaps to 12 volt. I want to keep six volt, but question how good the battery I was given is, even though it was new. I can only crank the car about 20-30 revolutions before the battery runs out of juice. No big deal when the car is warm because it starts right away. When I first crank it takes a while to build fuel into the carb. Now I cannot get the car started without being hooked to a battery charger. Is that just 6 volt, meaning you only get about 30 revolutions before dead, or do I have a weak battery?
 
#2 ·
The only way I know of to positively prove the output of a battery is a load test. Most auto shops and parts stores will load test a battery for free. The battery needs to be fully charged before the test.

The problem with 6 volt systems is that they are extremely sensitive to dirty connections and bad grounds. To work well, all connections need to be very clean. In my experience, a good 6 volt system will actually crank the engine longer (but slower) than a 12 volt system before it begins to slow down.

You might also try a different battery charger, especially if the one you are using is a newer one. Seems like battery chargers made in the last few years barely work at all...but that's a subject for another thread.

Hope this helps... :thumbup:
 
#4 ·
vwnutt said:
When I first crank it takes a while to build fuel into the carb. Now I cannot get the car started without being hooked to a battery charger. Is that just 6 volt, meaning you only get about 30 revolutions before dead, or do I have a weak battery?
You have some other issues that need to be addressed- IF- the car's not starting right up after sitting for a short time- like overnight or even a couple days.

In that short length of time, there should be no need to crank the engine over more than a couple revolutions before it catches.

If the engine isn't starting easily, there are several things it might be- but the first thing I would want to know is whether or not the choke is working- and if you know how to set it, if it is.

I'm not just blowing smoke here- my avatar is my DD '40 Pontiac that we had for YEARS.
 
#5 ·
fuel leak

You are right about other issues. The fuel line evaporates back to the pump, so when the vehicle sits for a long time it has to pump about two feet of fuel line. Whenever fuel is in the line, it starts right away. If it sits 3 months then it has to crank 20 times. Today I drove it the longest ever. Put about 40 miles on it and all was fine except the brake lights went out again. That a whole different issue from the battery.
 
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