tach. question

[brawley]

my truck came with the factory tach. there are 2 wires coming from the back of the gauge, 1 goes out to the distributer and 1 pink wire-looks like it might plug into the fuse panel, I changed over to HEI. cannot get the tach to work?? any ideas. thanks

[kwmech]

If the tach was working before the dist change, all you should have had to do was plug the tach lead into the place on the HEI that says tach. Nothing else to do that is special.

[71K20chevy]

One wire goes to negative side of coil (TACH terminal in your case of HEI) and the other goes to IGN UNFUSED on the fuse block. The cluster needs to be grounded good as well.

My truck has HEI, my factory tach is wired exactly like this and it works fine. Is your tach fried?

[brawley]

I changed to hei to get truck running, not sure if it worked before or not, I have the wire from the tach to dist. hooked up, and tried every position on the fuse panel for power, but still not getting it to work......also the fuel gauge is reading past full and does not move.. and rear lights will not work...Im thinking it might be a ground issue.. do I need to ground the engine block to the frame??

[71K20chevy]

You should have two grounds coming off the cab, that get sandwiched in the valve cover bolts. If you don't have those, then yes, you need a GOOD ground from the engine to the frame.

I ran a couple grounds from the frame to the cab, and a couple from the frame to the bed. Made my lights a lot brighter.


If your fuel gauge is reading past full, that means either there's an open connection somewhere, or it simply is not grounded.


I'll bet that grounding solves a lot of your problems, as it did for me