if you wind out 1st gear the tach will jump over to 7k or higher, i KNOW that the stock 305 isnt going to rev that high without floating the valves, at first I had thought that maybe it was reading twice the rpm's, maybe somebody wired up a tach and had fudged up the wiring, but the stock harness is unmolested. Are the stock tachometers very inaccurate or do I have a freak of a car being able to rev a stock 305 to 7000rpm???

 

different tachs are off a diff amount. sounds like yours it way out of calibration. did you happen to drop it at any point in time, as that is bad. you may need to have it recalibrated.

but on a diff note, most oem tachs are off a little (mine is off a 500 rpm) but it sounds like yours it really off.

good luck

anthony

 

MSD ignition will throw the tach WAY off unless you run the signal wire from the factory tach to the tach lead on the side of the MSD box.

I said screw it and bought an Autometer !