gauge cluster question

Well, right off the bat, just to make sure my speedo was accurate; I ran it beside my mom’s Windstar at 40, 70, and 120km/h. Once I got that settled, I went strait for the tach. It's a little tougher to do, but not impossible. It normally requires a little math skill...but since I'm feeling generous and lazy at the same time, I'll just give you a link to a calculator that takes care of the computations for you.
http://bbs.hardcore50.com/calc/?mode=rpmforspeed
Input the appropriate data and change the tach accordingly.

For instance.....
Rear End Gear Ratio: 3.55 (in my case anyway)
Transmission Gear Ratio: .68 (5th gear O/D)...4th if you're driving an Auto.
Tire Diameter (inches): 25.7 (which is what my 245/50/16's are.
Vehicle Speed (mph): 60 (that sounds like a nice round number.

Tah Dahhhh, my approximate RPM is 1894 (1900)

So, keep playing with the needle until you get it to read that at 60mph....or whatever speed you choose. Sound simple enough. It's not going to be dead on, but stock tach's rarely are anyway.

As for the other two problems…
Take the car to the gas station, fill it up and place the needle appropriately.
Start the car, bring it up to normal operating temperature and place the needle where you usually see it (they're not all that accurate to begin with)
There you go, dilemma solved