Tachometer Hookup Help - New Cluster!

[1972BlueC20]

Hi guys,

I need some confirmation on how to hook up the tachometer on my new reproduction cluster I just got in the mail today.

I already know (thanks to TBONE1964, VetteVet and ray_mcavoy) how to change the positions of the wires in the cluster plug to convert from idiot lights to gauges, and I know about running new wires from the # 1 (to alternator) and the # 12 (to the junction block) with 4 amp inline fuses on both of these new wires.

The only thing that is stumping me at this point are exactly how to hook up the tach, I just want to verify one last time before I do all this that what I have read and been told is correct and that I understood it correctly from those who were so kind to help me!

Here are pics of my new cluster (front and back) and a pic that I drew lines onto of how I think I can run the wires for the tach since I have HEI....also a picture of the tach harness that came with the cluster. I don't think I need this harness since it appears to be for a points style distributor and I have HEI.

I also have a tach filter, some say I should use it, others say I don't need it....if I do use it, how would it be wired into this equation? I read the instructions but I'm still not 100% sure how to hook it up.

Lastly, does the tach have it's own light inside or does the 2 lights on either side of the tach illuminate the tach itself??

[1972BlueC20]

and picture of the tach filter

[1972BlueC20]

picture VetteVet gave me

[hdff]

sweet lookin cluster. if ya can't get it figured out we can put it in my truck, I need a new one and it would be plug and play... lol

other that I think the one wire from the hei to the tack is right, I can't be of any more help...

[1972BlueC20]

Can anyone help on this?

I don't want to fry my new cluster hooking it up wrong

[1972BlueC20]

Hi guys

Surely someone has done this swap before and can help me

anyone?

[ray_mcavoy]

Originally Posted by 1972BlueC20

... and a pic that I drew lines onto of how I think I can run the wires for the tach since I have HEI

Yes, the way you have it drawn in that pic would work.

Originally Posted by 1972BlueC20

....also a picture of the tach harness that came with the cluster. I don't think I need this harness since it appears to be for a points style distributor and I have HEI.

Yes, that harness does appear to be for a stock points distributor. However, you could still use it with HEI by simply cutting the forked terminal off the end of the brown wire and replacing it with an HEI tach connector like this:

http://www.repairconnector.com/produ...Connector.html

Originally Posted by 1972BlueC20

I also have a tach filter, some say I should use it, others say I don't need it....if I do use it, how would it be wired into this equation? I read the instructions but I'm still not 100% sure how to hook it up.

If you use that filter, you'll want to make the following connections:

(1) Black wire to a good ground.
(2) Yellow wire to the "coil" terminal on your tachometer. If you locate the filter in the engine compartment, you could spice the filter's yellow wire to the tach harness' brown wire.
(3) Red wire to HEI "TACH" terminal. This connection can be made using an HEI tach connector like I posted above.

Originally Posted by 1972BlueC20

Lastly, does the tach have it's own light inside or does the 2 lights on either side of the tach illuminate the tach itself??

Illumination is provided by the 2 lights in the cluster on either side of the tach. So there are no separate lights to hook up.

[1972BlueC20]

Thank you so much Ray!!

This helps greatly now I can proceed.

Do you think I need the tach filter?

If I don't use it, do I risk frying the tach?

[ray_mcavoy]

You're welcome!

I don't think there is much risk of frying the tach by not using the filter. The filter basically just blocks higher frequency "noise" from the signal that could potentially cause erratic / jumpy tach readings and / or interfere with radio reception. But since you already have the filter, you might as well go ahead and use it to ensure a nice clean signal to the tach.

[1972BlueC20]

Ok, I got the back of the cluster all prepped to install with a tach filter in the equation just for good measure.

Picture is down below.

Everything is soldered and tight and taped and crimped.

Let me know if everything looks good.

The red wire with the spade connection on the far left side will connect to another wire that will run through the firewall and hook to the HEI tach input.

I've already got my new # 1 and # 12 wires ran from where they need to be with 4 amp inline fuses, ran through the firewall just need to connect them to the proper spots on the cluster plug. After that I just need to swap around the cluster plug wires from their original positions (idiot lights) to the new positions (gauges) and I should be good to go.

Otherwise I have to hook up the oil line, which I also have ran through the firewall ready to hook into the back of the oil pressure gauge. I also still need to connect to it where the oil sending unit is now. Line is copper and coiled to prevent buzzing (so I've been told)

I will also add one more ground wire from the back plate on the cluster to a bare metal spot just above the parking brake on the bottom of the dash.

Should I have everything taken care of??

[HIGHWAY BY THE SEA]

Where did you get the tach filter? I need one of those before I hook up my tach.

[1972BlueC20]

Originally Posted by HIGHWAY BY THE SEA

Where did you get the tach filter? I need one of those before I hook up my tach.

http://www.classicparts.com/1947-72-.../#.VxoUPjArLcs

[1972BlueC20]

For the new wires I will be adding to the cluster plug (#1 and #12) I know I can use the old blue wire(s) bow terminal (blue wire = old oil sending unit wire) but will there be another un-used wire in the cluster plug that I can steal the terminal from for the other added wire??

I'm talking about these terminals...