Low voltage when starting

[Justinb]

I'm trying to hunt down a problem with difficulty starting the car. It usually takes 6-10 seconds of cranking to get the car to start.

I measured the voltage at the alternator when starting the car and it's dropping from 12v down to 8v when trying to start.

I measured the voltage at the battery terminals when starting the car and it's dropping from 12v down to 11v when trying to start.


What would cause this kind of a difference? Do I need to worry about it or look in other places for a solution to my starting issues?

[Citron]

My first problem is with the battery voltage.  Afully charged battery should have a touch over 13 volts.
The drop at the battery is not a problem to me.  Don't know about the alt.

Steve

[Justinb]

The battery was fully charged and officially had 12.6 volts. I had left it on a trickle charger for about 12 hours to make sure it was fully charged. I also had the battery tested at autozone and they said it was good.

Originally, I was grounding my battery to the body with a 4ga ground wire, and then grounding the motor to the body.

I changed things around and ran two 8 ga wires right from the battery to one of the bolts that holds the slave cylinder to the bellhousing (Rover 4.2 + LT77 Trans). The car started dramatically better after making that change, but it's still not quite what I think it should be.

Next I'm going to replace my positive battery cable with a new one. I'm still using the original 1977 cable and I think the copper might be corroding inside the line.

Justin