Riddle me this...

harrisonm said

Very simple to check rear end gear ratio. Jack rear wheels off the ground. Then put a mark on the drive shaft and a mark on the tire at the very bottom. Then turn the drive shat slowly until the wheel makes one full revolution (the mark will be back down at the bottom) while you are counting the revolutions of the drive shaft. So if the drive shaft turns 3.5 times to get the wheel to turn once, your ratio is about 3.5:1. Assuming the tranny is not slipping, I doubt you have 2.76 gears.

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This only works on "posi" LOL (limited slip) rear axles. If you jack up one wheel and it turns you do NOT have limited slip. No do the the above, only count shaft turns and turn the tire TWO full turns.

Also, I've bought several GPS units from C/L and local thrift stores. They make a cheap easy and ACCURATE speedo

I agree^^the tach could be off as well. You can actually check a tach by downloading some musical notes (tones) running your sound output through a low to high impedance transformer (to generate higher voltage) and using that to feed the tach trigger wire. You have to calculate the tone frequency to V8 trigger frequency

I posted a thread on this years ago, never find it now!!!