The tach in my car reads insanely wrong. At a cold idle, it reads anywhere from 2700-3500rpm, while I can tell by ear that it's only around 1300-1500, and when warm, it reads ~1500rpm, and it's only around 900rpm. When driving, it pegs 7000rpm, and sits there, I kept my foot in it as long as I dared, it was still pulling, no valve float, shifted to third, it dropped to 6500 and then tached 7000 again for an eternity. If I remember correctly, a stock 305 stops making power somewhere around 5200-5500rpm.

Anyways, if someone can give me some insight on this, I would greatly appreciate it. I've been thinking about just installing another tach, but if I run it from the same wire as the factory tach, I'll have the same problems, correct?

EDITED: It's an 82 Z28 Pace Car w/ a transplanted 6 speed. The speedo doesn't work also, but that's related to the 6-spd conversion, and I don't think it has any relation to the tach not working properly.

 

Nobody has any information that might be able to help me? Guess I'll just install the big gay 5" tach w/ shiftlight from the moosestang.

 

the problem your describing is in the tach itself...the wire from the distributor/coil pack just sends a pulse for each time it fires a plug...the innards of the guage reads the number of pulses and then converts it to the correct number of revolutions. Either part of the guages electronics has gone south or the guage head itself has gone bad....see if you can get a replacement from the boneyard, just make sure you get one from a car with same # of cylinders

 

Thanks, I'll probably just install an aftermarket tach for now, as I have a couple of those sitting around. As long as it's the tach messed up, I can deal with it.

Rob