[chevyrestoguy]

I have heard that some of the repop tachs are hit or miss. If you don't hear any good info from Counterparts, then maybe a call to a professional speedo shop like Hollywood Speedometer or United Speedometer in Riverside would be helpful. Don't be fooled by their name, they fully calibrate and service all instruments. They maybe be able to give you some solid advice or offer a service where they'll calibrate your current tach to work with your ignition. It may be something as simple as a calibration or the addition of the correct resistor. If you're reading too low, you may be OVER-resisted, if that makes any sense.

I asked the counter guy at the Truck Shop a couple of years ago if their tach was HEI compatible, and he told me no. I like HEI ignitions, so I was going to have an old 5K Sun tach I had laying around converted by Williamson's to modern internals that were compatible with my ignition. I never got around to it because another member theastronaut (his name is John Glenn) had a custom 10K tach made by Jason Wilson at Greenback Decal that looks 100% factory. I liked it so much that I had Jason make me a 7,000 rpm tach and it looks great. I'm still wiring my truck, so I have no info on how well it performs. Jason is a smart guy, and I'm certain that it'll be just fine. If you look at theastronaut's build thread, you'll see what the tach looks like.