Electrical problems

[Squareforceone]

Okay so I have an 84 c10 that i pulled the 305 out of and put in a 350 with headers ever since then it's had a problem starting when it's hot. So i put a heat shield on the starter to see if the headers were heat soaking the starter and it had no change. So i bumped down the initial timing to next to nothing and still had no change.. The 350 wasn't built by me and was giving me head aches so I pulled it out to rebuild and put in a different 305. Well the 305 is stock minus headers and intake/holley carb. Still having the hot start issue. But now on top of that the truck randomly won't charge. Took it on a few drives were things were fine others where the battery started going dead while driving. One of these times I brought it home and put my fluke on the battery and it read 9v while charging (know good alternator) Then today I started it put the volt meter back on and it read 14v running. I'm assuming I have a bad wire rubbing somewhere?? I've cleaned up all the grounds but still have had the issue. Where all should I check? Thank you.

[gmachinz]

Sounds like you have a binding/sticking ignition switch down on the lower part of the column. When you turn the key to start the engine it delivers 12V to the starter and bypasses the charging circuit....then once engine fires and you "relax" the key, it triggers the charging circuit by providing 12V to the "excite" wire to the alternator. Check the switch wiring or as cheap as they are, maybe just replace it and see what the result is.

[rich weyand]

You might also check the voltage drop across the positive and negative battery cables. These are known to fail internally with no outward sign, and can be intermittent with temperature and other factors.

Set the voltmeter to read DC volts, and connect the voltmeter to the two ends of the cable, then have someone crank the starter while you read the voltmeter. More than half a volt, replace the cable. Do this on both + and - cables.

[Squareforceone]

Originally Posted by gmachinz

Sounds like you have a binding/sticking ignition switch down on the lower part of the column. When you turn the key to start the engine it delivers 12V to the starter and bypasses the charging circuit....then once engine fires and you "relax" the key, it triggers the charging circuit by providing 12V to the "excite" wire to the alternator. Check the switch wiring or as cheap as they are, maybe just replace it and see what the result is.

how do i check it?

[Squareforceone]

Originally Posted by rich weyand

You might also check the voltage drop across the positive and negative battery cables. These are known to fail internally with no outward sign, and can be intermittent with temperature and other factors.

Set the voltmeter to read DC volts, and connect the voltmeter to the two ends of the cable, then have someone crank the starter while you read the voltmeter. More than half a volt, replace the cable. Do this on both + and - cables.

do i start with the key in the on position then look for a drop while cranking?

[rich weyand]

Originally Posted by Squareforceone

do i start with the key in the on position then look for a drop while cranking?

All you need to do is read the voltage from one end of the cable to the other while cranking.

[Squareforceone]

I get that but it's a drop test. whats my base line voltage through the wire with the key on not cranking?

[rich weyand]

You don't get it or you wouldn't ask that question.

There is no base voltage. You want the drop, from one end to the other of the cable while cranking, and you measure that directly by just hooking the voltmeter to the two ends of the cable. That is, you don't ever hook the voltmeter to ground and measure battery voltage or voltage to ground or what ever, you connect the two leads of the voltmeter to the two ends of the cable at the same time, and see what it measures while cranking.

[gmachinz]

You'll need to probe the actual wiring @ the ignition switch using a voltmeter. There are lots of ways to verify whether the system is/isn't charging, etc. I would try to move the ignition switch rod a little both directions and see if any of your wiring output readings fluctuate coming out of the switch.

You can measure amperage draw for the starter by using an inductive amp probe....it isn't uncommon to see 75-100 amps when cranking. If its unusually high like 250-350a or more it could indicate worn starter bushings/bad windings.

[franken]

Sort of sounds like 2 problems.
What exactly happens when starting? The original question is sort of like, my girlfriend makes me mad. Please tell me why. Not overly informative.