alt gauge 69

where should the amp gauge needle be positioned when the engine is running on a 69 camaro with factory gauges. I think I might have installed the MSD diode in backwords. Can anyone tell me, in idiot terms, which way the diode goes ? My gauge needle is positioned just to to the right of center, about a needles width, when running. There is no change when the headlights are activated.

Thats about where it should be, All that means is that it is feeding current into the battery when the car is running. A stock Ammeter does not show how much current is coming out of the alternator but whether current is going to, or coming from the battery. With the car off, turn the headlights on, the needle should deflect to the left of center a needle width or so.

Mark, tried the lights and the needle did go ever so slightly to the left of center, and when it's running it ever so slightly goes to the right, but I still don't think it is charging If the motor runs fo a while and I shut it down and start it up several times the engine cranks over real slow and then just stops cranking. everything is brand new and when the battery is fully charged it starts no problem. How can I check to se if the alt. is charging the battery?

I don't think you understand how the factory amp gauge is supposed to work. The amp gauge only shows the battery's charge or discharge rate. Starting with a fully charged battery......In a amp gauge car, with the car not running start by turning on items in the car, high beams, fan blower on high, brake lights ect... the more thats turned on the farther the amp gauge will show discharge. With everything possible that was original to the car turned on, the gauge may be close to max discharge. Now turn everything off and start the car, the needle will move towards charge a little (not even to the first line) and may stay there for a min or 2, than settle close to the center mark, about a needles width on the charge side. While driving the car and everything working properly this is where the gauge will normally be. Now turn the car off, turn on the high beams and leave them on for 20-30 min or so to take some of the "charge" out of the battery, then turn them off and start the car. Now that the battery's charge is lower, the amp gauge will move farther towards the charge side. As the engine RPM varies, you might see the amp gauge vary the charge rate as alternator output changes with engine RPM (at idle it may be close to the center mark, at 2500 engine RPM, it may show a medium charge rate. As the battery becomes fully charged it will slowly settle close to the center mark, about a needles width on the charge side. Anytime you see the amp gauge on the discharge side with the engine running means either the charging system is not working or the cars current demand is greater than the alternators output, and you are just running off the battery. On factory high performance cars (Chevelle LS-6's, L-78's, Camaro Z-28's) these cars came with a larger deep grove alternator pulley. alternator output was lower than the the low perf cars at any given engine RPM, battery discharge at idle was sometimes a problem, especially if other accessories was turned on.