I just installed a tach in the 68. Older 350 engine (nothing special) th400 and a 8.2 rear that I'm unsure of the gears but I'm bettine there 3.42 or lower. The tach says the car idles around 700-800 and if I mash the gas during driving I didn't see it go over 3k even though it sounds like it can't go higher lol. Normal crusing at 50 mph is around 1.5k. Did I wire it up wrong or something because it just don't seem right. Those rpms when I hit it should be much higher I think. Any input on this guys?

 

stock or after market tach. aftermarket tach should have a screw to switch to 4, 6 or 8 cylinders, you may have it on 6.

 

Its on 8 cylinders, could a bad connection make it read wrong? Imma test that tomorrow. Even with the car in park and me revving the engine it just don't seem right.

 

know anyone with a dwell tach, easiest way to check

 

What make of tach did you use, and which wires did you connect to what?

 

Sunpro super tach 3. Green went to negative (I believe) on the coil. Black to ground, red and white to hot while car is running. I'm pretty sure all wires are connected correctly but lets just say I connected the green to positive on the coil, would that effect it?

 

The tach reads ignition pulses, which is on the negative side of the coil. You wouldn't be getting an ignition reading on the positive side of the coil. Since the coil runs off a resistance wire (less than 10 volts), make sure your red tach wire is from a source isolated from the power feed to the coil. If you question the integrity of that red wire hookup, run it straight to the battery as a test.

 

I ran power to the tach directly to the battery and nothing changed so ill rule that out. I hardly believe that it is reading right so what do I check now?

 

20 or 30 bucks for a dwell/tach/volt meter. i think sears has em for 25.

 

what kind of an ignition system are you running?