have a 71 rs.tach does not work.when i got the car a few years ago, it didnt work but the previous owner installed a hei dist.no big deal.since then i replaced the engine with a crate gm 350/330 hp engine that came with a hei dist.my question is what is the color of the tach wire,my wiring diagram that i got from classic industries is not showing any tach wiring.i do have a brown wire coming through the firewall just left of the brake master cyl,.it does have a aftermarket female spade connector on it.can anyone tell me if this is it for sure.i dont want to just hook it up and see what happens.thanks,brad.

The STD OEM Tach wire is BROWN for 70 & 71 which a point Distributer and connects to the Negative Terminal of the Coil. I assume you have the U14 Cluster as you have a Tachometer. To tell you the truth I've never run an HEI as I've always went to an after market CD Module. I would assume the HEI module has a TACH terminal which you can connect the brown wire to. If the tach does not indicate properly, whch I doubt as I've never had problems with these tachs, you may require a filter.

Don't confuse the BROWN wire with the TAN wire that connects to the Brake Warning Switch.

HEI dist have a TACH terminal next to the BAT terminal. It may require a filter for the tach to read correctly.

Same concerns as Bulven...anyone else know if hooking the brown wire up will work the tach correctly? What filter are you talking about?

The condensor looking filter thing is not needed for the tach to work properly. The tach wire runs from the plug next to the one labeled batt on the HEI distributor to the #1 slot that plugs into the back of the insrtament cluster.