power

GordonThree wrote:
just curious, what is the benefit of two tachometers?

I have two gauges but not two tachs.I have a tach and a vacuum gauge.It is a 92 chevrolet p30 chassis with a 454 big block.The coil is a 92 hei.The type that has the 2 plugs with 2 red and 2 white wires.I hooked the signal to one of the white wire and it is a little jumpy and not reading right.The needle is moving without any unswiched power hooked up.That is what puzzled me.I got the gauges from glowshift and they offer a filter for the hei.I will be giving that a try.

just curious, what is the benefit of two tachometers?

Roadpilot wrote:
The tach needle is probably driven from the tach pickup. The 12 volt connection is only needed for a back light.

Ok sounds right to me.Are there anything wrong with running both gauges off the same ground and constant power?I have 92 gm coil the efi kind with the four red and white wires and spark plug.I went off the white wire for the tach signal after later on finding the test port taped to the harness.

Roadpilot wrote:
The tach needle is probably driven from the tach pickup. The 12 volt connection is only needed for a back light.

My guess as well

The tach needle is probably driven from the tach pickup. The 12 volt connection is only needed for a back light.

quantum tunneling, or maybe osmosis?

really need more information to figure out a why. as far as there being anything wrong - if the gizmos are working the way you want them to, sound's good to me!