66 Ammeter Issue

[jnirenstein]

HI everyone,
Just finishing up my 66. Having an issue with my ammeter. before I replace it I figure I'd consult the experts! I have upgraded to a stroked 289 and a C4. The alternator is a standard 66 Mustang alternator. It has been bench tested and the output is fine at approx. 14.5-15V. The voltage regulator is also new and is a standard (non-solid state) version. The ONLY thing that is original to the system is the gauge in the dash cluster. What I am experiencing is that the gauge reads fine upon start-up and idle. When I give it gas in park it smoothly moves up showing a positive charge. After a couple minutes of driving however the gauge starts to "bounce/Jerk" upwards and then back down to the center between D and C. It does not settle down unless I come to a stop or park it. ANY thoughts would be appreciated. Perhaps I'm getting some "interference" on the wire loop through the back of the gauge as the current increases with RPM????
Cheers,
John

 

[Broncobowsher]

Pretty normal. Are you still using the old mechanical voltage regulator or an updated solid state regulator?

 

[jnirenstein]

Pretty normal. Are you still using the old mechanical voltage regulator or an updated solid state regulator?

Mechanical. So that behavior is common And not to worry? Or not a bad gauge?

 

[Broncobowsher]

More of them do it than don't. There has been a lot of chasing it to smooth it out, sometimes it works, often it doesn't. I never could get mine to calm down. It was enough to tell me if it was charging, or not, or somewhere in the middle. If it is calm and zero or below, I'm at a loss. Steady and positive, taking a charge. Bouncing in the middle, regulator is regulating.

 

[Oldtimer]

Mine bounces. If I turn headlights on, the added load calms it down.

 

[Gas Pig]

Yep mine has been bouncing for 15 years. The guys say your ground might not be the best… obviously you have a ground but it have some resistance somewhere in the system. Also like mentioned doing a solid state voltage reg helps too. The bouncing needle kind of drives my nuts too, because something not a 100%… I have other ‘66s the garage works smoothly. I really don’t think it’s the gauge but that one is easier to get to then the others.

I know I just made it clear as mud! lol