I recently bought a '72 tach to put in my '72 skylark. I'm wondering if it hooks up to the pos. or neg. side of the coil. And, I need the 5/8" diameter lights that plug into the back. Any ideas on where I can find the lights?? Any help would be appreciated. I am new to this forum and it is VERY informative. I'm back in the game after a 13 absence. I recently bought back my first car ('72 skylark) after selling it in 1995. Its a long story, but she's back now and will stay with me as long as I'm around. Still in great shape and a great driver quality car for now.
Negative side of the coil if using points. As far as the lighting, there should be two gray wires with the bulb sockets back there. Have you looked? The lighting for a clock and tach are the same. All cars should have the wiring regardless of how they are optioned. 1893 are the bulb #'s
You can also buy the correct factory style tach wire new from one of the wiring suppliers either M+H or Factory Fit. There are two parts to the wire I believe and it is brown if you do not have one.
Also factaory tach wire ran through a rubber grommet near the brake booster that your car probably will not have and hole will not be drilled either.(big hole needs hole saw) To do it correct you need some more info and parts.
I have not been into the dash yet. Right now it has no clock, just the delete plate. The tach itself just has the two 5/8" holes in the back, where the lights would go.
Thanks for the help guys. I was waiting on a shop manual before I got into the dash. However, I am open to suggestions if anyone knows what I need to do to get into the dash and install this tach. Thanks.
I ran the tach. wire thru an existing grommet in the firewall. Midway across the firewall where the heat/AC vacuum tubes & wiring exit the dash area. I wasn't looking forward to cutting a hole in the car. I put a male/female factory style connector just outside the firewall per factory & ease of removal when engine comes out, which is where I am now. Pay attention to the drawing in the manual, for '71 it's # 120-43. A ground strap will be needed between the tach. case & the speedo case. Factory used a small busbar stock & I was able to find one. This can easily be made from a piece of wire with ring terminals under the mounting posts for the instrument case.
Well, I tested the tach under the hood and it read about 500 rpms low. I had it hooked to neg. side of coil and I had it grounded. Does anyone have any suggestions, or do I need to send it off to have it calibrated?
did u test the tach against a known correct tach? installing the tach into the dash is a pain in the a$$. if u donot remove the the dashpad, then u better have long thin fingers, small hands, and arms.
Well, I know that my idle is set at about 650. This number is verified with my digital timing light. When I hooked the tach up, it reads about 100 rpms. When you rev the motor, the tach comes up with rpms, but it still reads about 500 rpms low. I haven't installed the tach in the dash, this test was done under the hood with a lead to the tach and one to ground. Any ideas? Thanks.
