Battery Draw

[David Stoehr]

I've been having difficulty starting my 1957 Carrera.
After numerous attempts only the port side fired so, we changed plugs on the starboard side.

However, throughout the investigation process we worked the battery pretty hard. It got to the point where it would die after 15 - 20 seconds of cranking so it was replaced with a brand new one having the exact specifications (600 crank power / 100 reserve). The new battery also dies after 15 -20 seconds of cranking.

I noticed that the generator light is only half lit (bottom half) when the ignition is switched on. I can't recall if it this light was always half lit or is this an indicator that something is wrong with the generator thus draining the new battery very quickly.

The new battery is dated July 2024

Any conversation is welcome ...

Appreciated
David

[Harlan Halsey]

Well, it doesn't take 15 seconds to start any 356 if it is Intune and the float bowls are full. Going through the ignition/starting system is a multi step process. Until you indicate why you expect the car to start, and what you know about checking out the system it makes little sense to offer help. 356A Carreras are notoriously prone to plug fouling. A Carreras Autopulse fuel pumps are finicky. Jumper cables should alleviate your battery concerns. The generator light housing is just old. Where are you located?

[David Stoehr]

Hello Harlan -
Thank you for your reply.

This particular year the car had to sit untouched for months so when this extended period of sitting occurs it always takes more time to get if fired.
There is no check valve on the oil tank, so the heads fill up with a lot of oil; But it always started after a few minutes of cranking and burned off the excess oil.

We have fuel flowing to both carbs as evident at the banjo fitting.
The carbs could have been clogged from evaporated fuel residue, so we removed the air cleaners and primed them with fresh gas.
After an extended crank period the left side fired but not the right.
Attempts to get the right side to fire lead to the battery only lasting 15 seconds when fully charged.
Replaced all 4 plugs on the right and installed brand new battery.
The new battery also only lasts about 15 seconds of cranking. The engine started to fire but the battery would check out.

Yes, we can try jumper cables however, I'm concerned as to why the old and new batteries all of a sudden die with a short crank time when at one time they would last for minutes

Feel free to call me if you like.
Your conversation is appreciated
724-745-1405
David

[Harlan Halsey]

So western PA. Quite a way from here.
15 minutes is a very long time to crank. Electric starter motors are intended for only brief usage before they overheat. (Check out the history of the electric starter.) L19 6v batteries have a capacity of about 80 ampere hours. The starter motor should draw no more than about 150 amps. So a good battery should run the starter about 1/2 hour-but the starter motor will be overheated to destruction long before that. The bushing problem with Carrera starters is the same as with any 356. As are the other electrical issues with the elapse of time.

Carreras with worn oil pumps drain the oil tank back through the pump into the crankcase. My Carrera will go for more than a month without noticeable drain back, Chuck Forge's in a few days. Oil in the crankcase is dangerous, if it gets into a cylinder, disaster. So always drain the crank case oil before starting if the oil level in the tank is down by a couple of quarts or more.

My Carrera is easy to start because I, disgusted with hard starting, changed over to modified normal projected gap plugs, decades ago. (The mod is not trivial but not that hard either.) Stock plugs are side gap plugs which hide the spark up out of the combustion chamber.

[David Stoehr]

Thanks for your reply.

I said 15 seconds of cranking not 15 minutes.

Would you like to speak with me over the phone ? Seems like you have a lot of technical knowledge so, if you're interested, we can eliminate a lot of messaging..

My cell is 724-747-1817

Please let me know.

Thank you
David