Voltage drops during cranking after a cruise

[Chuck Step-a-side]

I have 1984 Chevy Silverado with a 350 and Edelbrock carb and manifold. I will keep my truck on trickle charge until the weekend. After taking it for a drive; I'll pull my into truck driveway and shut it down and then crank it over again. The starter cranks over sluggish and I can watch the voltage drop to about 8 volts for a few second and then it will start.  I have had this problem with starter cranking issues a while which is why I'll crank it over again to see if it will start over normal. I've gone thru the engine harness and ohm out every connections and then check for voltage drop and positive tests with my voltmeter and all checks normal. The alternator shows a constant 13 volt reading during idle and cruise. The starter and ignition switch has been replaced. I have a 875 amp battery with clean terminal connections. I haven't replace the alternator because I see the 14 volt reading on my gauge cluster. I know I have a voltage drop issue, but I'm at my last straw. Any help is appreciated.

[VileZambonie]

If you have correctly performed voltage drop tests and your ignition timing is correct, then most likely you need to replace the starter. What was the voltage drop reading across the negative post to the engine block? What was the voltage drop reading from the positive post to the starter Solenoid B+ terminal?

[AZ4X4SQBDY]

I would test for voltage drop from positive battery to engine block and see what the voltage is there when cranking, then take a pair of jumper cables and go from battery negative to engine block and see what the voltage is then.

Battery cable once overheated or blued do not pass current correctly anymore. It will ohm out fine but doesn't pass the current needed also I have seen more than one bad OEM battery cable that had corrosion once you cut back the plastic protector. It looked fine when you disconnected it from the battery and visually examined it but didn't find out it was bad until it was cut apart.

I agree, double check timing and both advances working correctly. It could also end up being a starter also.