Ok I just got our 72 chevelle running after it sat for 17 years. I have been driving it to and from work without a problem. Until the last few days. It cranks for 10-12 revolutions and does not want to start. If I jump it off another car it fire up almost immediatly. Does this sound like the battery is not putting out enough to turn the starter and power the pertronix distributor? I'm pretty sure the pertronix needs the 12 volts to start, and when its cranking I took a reading at the batttery and it would start off at 12.6 volts and then drop to 9.6. At that time everything dimmed and the battery would die. When I crank it over I also noticed unless I'm jumping it that the lights all dim and the cranking is not as fast as it is when I'm jumping it off. Once running, voltage at the coil is 12.1, the alternator reads 13.6-7, the battery reads about 13 (its mounted in the trunk so there may be a lot of voltage drop) Anyways I was just wondering what you guys thought, I was thinking maybe the starter was drawing to much power but it seems to be working great when I jump it. It is not a heat soak issue, it happens even when its cool. BTW its a 468, pertronix ignition, and I have checked and rechecked all the connection to the distributor to rule that out. Thanks a lot.

Oh and all the battery connections are good, including the ground that goes to the frame back there in the back. I cleaned it all off last night and reconnected it just to see. Thanks again.
J.D.

I'll take a guess. You may have corrosion INSIDE the cables running to the battery in the trunk. Cables can look good at the connections, but corrosion could have set elsewhere. If those cables have been there for the last 17 years, I'd replace them. Use 2/0 gauge or maybe even 1/0.

Like you observed, voltage is dropping quickly. I had a similar problem a few years ago and after replacing the battery, starter (with heat shield, shielding on wires), the damn thing still had major voltage drop and wouldn't start. I replaced the cables with a 2/0 negative and positive (custom built at a battery shop) cable. Problem has never shown it's face again smile.gif

That's my $0.02. Keep us posted.

Second that.

If the battery voltage is dropping to 9V or so when you begin cranking the car then the battery is likely junk.

The other reason I'd suspect the battery is because you can boost it and it will start. If there was a bad cable, boosting it would not eliminate the cable and it still would not start any better.

You should get the starting system checked to make sure the starter isn't drawing excessive amps and killing the battery. Basically, you measure the starter current while it's cranking the engine. I think a little under 200A is about right for a typical heavy duty GM starter.

Peter