Solved- 1955 Warm start problem

[ion]

For over a year I've been trying to figure out why my '55 will start just fine when the engine is cold, but will crank until the battery seemingly runs down but usually not start when the engine is warm. The solution turned out to be replacing the battery cables. I replaced the battery to ground cable, battery to starter solenoid cable, and solenoid to starter cable with gauge 0 new cables, and the problem is completely solved! The reason why this can be a problem is that that the resistance of the cables increases with temperature, and if the cables are rusted or corroded anywhere, this may result in a reduced voltage at the starter when hot, and a slower cranking or failure to crank at all. This is particularly a problem for the '55 which is only 6 volts to begin with.

Just for your amusement, here's a list of things i tried before this that didn't help: replaced the starter, replaced the battery, insulated the fuel lines (in case of vapor lock), replaced the generator with an alternator (which was a good thing to do anyway). I was about to add an extra spacer between the carburetor and engine block and look into finding pure (non-ethanol) gasoline in case the fuel was boiling in the carb due to heat soak. Of course, all these could be the problem in other cases, but not in mine.

I'm super happy to have finally solved this problem, because up to now I've been afraid to drive this car anywhere where I have to turn the engine off before returning home again. Hope this helps someone in the future.

P.S. I bought the new battery cables from https://www.batterycablesusa.com, very happy with the quality.

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[Oly Bob R]

What size cables did you use for the cables from battery to starter and ground

 

[ion]

It’s listed as 2/0 AWG. Lower AWG means thicker cable, but not really sure what the 2/0 nomenclature means. Here is a link to the specs for various AWG sizes:

https://www.batterycablesusa.com/assets/images/battery_cable_compare.pdf

The new cables are thicker than the originals but could still fit into the existing clamps on the firewall. Also to note when replacing the cable to the starter is that it passes very close to the exhaust pipe, must prevent it from touching or the insulation will melt.

 

[59tbirddavid]

Congrats, you have done what should be done when a person owns an antique vehicle. Observe the problem then speculate or give percentages to cause, do the forensics .