In reference to "amping amp gauge"

[2man]

Just to let you guys know I took the dash apart and did not find any bad wires. No brittle insulation from over heating or anything to suggest I might have a dash fire soon. But, thanks for the heads up. I still have the problem, but I dont think I correctly described it earlier. What it is doing is this: when I'm just putt-putting around town , no problem. However if I slowly accelerate to about 50 or so its fine. But when I floor it, the gauge goes over into the - side and a/c barely blows lights dim etc. etc.. Then if I let off the gas and let it coast everything comes back up and the gauge goes over to the + side. This only started after I installed the MSD ignition system. Not imediatly after but after nonetheless. I had a guy check the Alt. and battery an he said everything was fine. What gives? Any ideas? :confused:

[J20fan]

I had a alternator pulley slipping on my Jimmy this summer. Did not cause the exact problems you have but my battery kept getting too low to start the truck. I discovered it could just spin on the shaft when I went to put on the spare. engine mount letting the engine lift jamming or pulling a wire under high torque? I know silly stuff but it will surely be just that.

[Driftwood]

What is the amperage rating of your alternator? I installed a new alt last night in my 84 gw. NAPA had 4 rated alternators. The one I bought was 78 amp output rated. The next one up was 85ish rated. The other two was 50ish and 60ish rated. When the guy checked your alternator, how much of a load did he put on it. And what was the amperage draw of the alternator? That should give you an idea of your alternators' rated amperage. It may not be enough to provide power for that new MSD ignition system. There are alternators out there that put out over 90 amps, but you will pay a bit more for them.

[Snakeyes_Tx]

2man, yours is doing the exact opposite mine is. I believe you have a regulator issue.

I "fixed" my amp needle from bobbing too much by bring the idle up to about 1100. Even then in gear and stopping with everything on, it tips to the negative a hair.

My 86 never had this problem, but then again, it had a voltmeter, not an ammeter.

[Dive 30]

OK . . . so, when you romp on it, the MSD tries to slam a bunch of sparks=higher amp draw than stock ignition module.

1.)How is your MSD wired? Did you put it over on the Driver's side and have to splice some feeds to it? Is it grounded to the frame or the battery? Is the hot direct from the battery or is it through the amp meter?

2.)Did you leave the existing ignition module and use the red wire to the old coil + for the ignition +?

3.)As asked above, what is the amp rating on your alt.? Mine is 140 AMP, stock FOR ME was 85.

4.)What kind of shape is the battery to body and battery to motor ground straps? Stock, my battery to body ground was a 14 ga. wire that was pretty toasted and the bond to my AC was so frayed and warn it was a wonder that it even held together. Also, there is a bond wire on the Driver's motor mount from motor to frame. These components are all key to getting low-draw fast spark out of the ignition system.

Ideas:
a.)MSD is drawing excessive current. This could be the result of the unit being grounded to the body (MSD recommends being attached directly to battery for both + and - terminals). Positive run to MSD excessively long. I wouldn't think that splicing on ton those 10 or 12 ga. wires and running them an extra four or five feet would have a voltage drop, but it is a possibility. This theory would be very possible if the MSD's + was run through the vehicle constant hot system (i.e. the yellow wire that runs from the battery to the firewall through the amp meter and everything else).
b.)old ignition unit has gone bad. These units have a history of causing intermittant electrical problems, however, because of the MSD the vehicle would not stop running, it might just mess with you.
c.)Grounding problem. Increased resistance through the system would cause higher amp draw and surging as the altenator attempts 'charge past' (as mentioned above) the new higher current/voltage requirement.

Solutions: Obviously there are some replaceable key components there, but adding a capacitor (such as the MSD noise filter) or .5 or 1.0 Ferad capacitor (like they use for big stereo systems) would buffer the charging system from 'slamming' such as sudden bass hits or other high current stuff.

Hope that helps.

Phil