I have 73 Vette with 350 all wires look good on distributor and cluster but don't see any issues. car was sitting for a few years out side but it does run. need help!

 

Pull the tach drive cable out of the distributor. With the engine running, check to see that the tach drive shaft in the distributor is turning. If the shaft is not turning, then you probably have stripped gears on the tach drive shaft. This is a common failure. When replacing the tach drive shaft, ensure the plastic button on the opposite end is still there. If not, then it will need to be replaced also.

Another possible cause would be a broken drive cable. Or lastly, the tachometer itself may be broken.