Topic: dancing amp gauge needle

[CCP]

    The amp gauge on this '66 seems to be fine when I first fire it up, but after only a few seconds begins to fluctuate wildly from side to side, full range of the gauge. The alternator has been rebuilt and the voltage regulator is new. The battery shows 13.1 volts and then jumps up to about 15 with the engine running and a volt meter on the battery terminals.
  Any ideas? Could the gauge be bad? 

            Thanks, Pete.

[midlife]

Midlife had this same problem, but intermittently, and I was never able to fully rectify the issue.  Now that I know more, I believe there is a problem in connectors or junctions where the ammeter lines are in the engine bay.  If you have a flakey connection inside a molded connector, you'll see rapid changes in resistance and that will be reflected in the ammeter gauge itself, which is designed to accept about 1-2% of the full charging current. 
Try tugging on all of the current-charging wires relative to the molded connectors.  Also, crimp ever so slightly the 90* slip-on connectors for the ammeter gauge to ensure they have good connections.

[CCP]

  Started by changing the voltage regulator. Put the original one back on and guess what, problem solved. That was something I didn't consider at first since the regulator was a new reproduction right out of the box. Lesson learned, even though something is 'new' doesn't mean it works properly.
  Now,  should I switch to a modern electronic regulator and church it up with the reproduction cover?

                Thanks again midlife.  Pete.

[CharlesTurner]

Electronic voltage regulators are usually the best choice over the old style breaker-points.

Thought I saw recently that there's a reproduction VR now with the correct base/cover and electronic internals?

[CCP]

  That sounds like the hot ticket!   Thanks.

[Bob Gaines]

Electronic voltage regulators are usually the best choice over the old style breaker-points.

Thought I saw recently that there's a reproduction VR now with the correct base/cover and electronic internals?

Virginia Mustang sells them . I am not sure about NPD.

[CCP]

  The new one that was bad came from Larry's. I have a box full of parts like that from them.

[70cj428]

  The new one that was bad came from Larry's. I have a box full of parts like that from them.

Probably not just Larrys, the repro regulator with the conventional (old school points) internals are pieces of crap and I think most of the suppliers sell the same part. Most people buy one, and end up stealing the cover off it and installing it on a new, Motorcraft regulator ....

JMHO, John

[preaction]

Midlife had this same problem, but intermittently, and I was never able to fully rectify the issue.  Now that I know more, I believe there is a problem in connectors or junctions where the ammeter lines are in the engine bay.  If you have a flakey connection inside a molded connector, you'll see rapid changes in resistance and that will be reflected in the ammeter gauge itself, which is designed to accept about 1-2% of the full charging current. 
Try tugging on all of the current-charging wires relative to the molded connectors.  Also, crimp ever so slightly the 90* slip-on connectors for the ammeter gauge to ensure they have good connections.

Is Midlife talking about Midlife in the 3rd person ?

[midlife]

Is Midlife talking about Midlife in the 3rd person ?

No, Midlife was talking about Midlife the car (1966 GT fastback).  When he talks to himself, an argument immediately ensues, so that's a no-go.  Shut up, you twit...I told you twice already.  No...you shut your pie-hole!
*sigh*

[jwc66k]

No, Midlife was talking about Midlife the car -

An object lesson is presented, you should have identified the car as such, "Midlife, the car". (Reminiscent of "My Mother, The Car" - naw.)
Jim

[Mike_B_SVT]

No, Midlife was talking about Midlife the car (1966 GT fastback).  When he talks to himself, an argument immediately ensues, so that's a no-go.  Shut up, you twit...I told you twice already.  No...you shut your pie-hole!
*sigh*

Heh...

[1967 GT]

I had the same issue in my SW under dash gauges. I purchased a NAPA solid state unit and used my Dremel with a drum sander to shape the resin encasement until the reproduction cover was able to fit the regulator. No more erratic needle operation on the ammeter gauge.

                                                                                                   

[CCP]

  I did go with the solid state one. Works perfect.

[Bob Gaines]

I wanted to caution that the extra work of converting to electronic insides to your previously mechanical regulator are wasted if you are converting a poor reproduction IMO. If you are going to the effort then it makes the most sense to convert something that is correct looking on the outside to begin with IMO. Some repro mechanical regulators have a incorrect base or a incorrect or poorly executed stamp on the cover . If you don't know the difference it would be prudent to find out what you don't know before wasting your time IMO. Of course as I mentioned before some vendors offer a regulator with correct base and nicely done cover with electronic insides that are nominally priced .