I went this weekend and had my mechanic check and set my timing. when he was done he turned the car off pluged the brown timing wire back in and started the car up. well according to the stock tach the engine was idleing in park at 2000 rpm, so he pulled his timing light back out, and re connected it to the #1 plug. comes out the car was actually idleing at 850rpm.(he has a snap-on digital timing light that displays the engine rpm's)
so I went and got an aftermarket tach. it's a 2 3/4" sunpro supertachII(I did not want any thing big and goddy), which I was told are very reliable.
so now Im getting completly diffrent rpm reading's than what the stock tach show's and want to check to see if they sound right.
it's a 305 TBI and all mods are listed in my signature.

at idle in park I get 850-900 rpm which matches what my mech told me.
idle in drive is 600-700 rpm
driving at 30mph I get 1200 rpm
driving at 60mph I get 1600rpm
And no matter how hard I try I can barley get the engine to go above 4000 rpm befor the trany shifts gears.

Do those rpm #'s sound right? if so then that meens my stock gauge is off x2 at all times and would explain why Ive hit 7000rpm by the stock gauge several times and havent managed to kill the engine!

 

Sounds pretty typical, actually.... the stock ones always read high, sometimes ALOT high....

THe factory considers it a "trim package" (fancy eye-candy gewgaw) rather than an "instrument". Their engineering of it follows that approach. Yeah, let's make sure it moves around, ALOT, so the buyer thinks it's doing something and really likes it....

 

7 grand, huh? I don't think you ever turned that kinda rpm. I think it is weird though. My stock tach is pretty close. It is about 300 rpm to high all the time, not 2000 rpm like yours. The aftermarket guage is better anyway...