I found my tach off by 200 rpm in 3rd and 300 rpm off in 4th in general. The amount I'm off varies to what rpm and gear I'm in. For example in 4th at full throttle at 6,500 rpm I'm actually at 7,000 rpm (500 rpm's off) but at 3,500 rpm's crusing in 4th I'm off by 300 rpm?
Always made me wonder how one can adjust the tach..............what rpm do you adjust too..............idle, 3,500 rpms 6,500 rpms when it is off by different amounts at different rpms and if you set it at idle will it be correct when the throttle peddle is floored rapping through the rpm's?
Sometimes I think the stock tach is not able to keep up when you are screaming up to red line.
I have a programmable digital shift light that has a digital tach that I use on the track to give me the true reading and my shift point is determine by a flash of the shift light vs looking at the tach.
I have adjusted the speedo to be coorect as per John's thread but my tach does not have an adjustment screw. I think that was gutted when it was sent off to Palo in San Fran to work with the aftermarket ignition.
The speedo is dead on after the adjustment. It took several trys but it's nice to know how fast your going. It didn't stop me from getting a ticket last Summer though.