Mark,
Check the tag (solenoid cover) on your o/d unit. Is it blue or black? Your
car (72) should have had a black label, requiring the 1280 speedo. If you
used a blue label o/d, then your speedo is turning 280 tpm (turns per minute)
slower than normal, resulting in a slower speedo reading at the same engine
rpm. The blue label box uses the 1000 tpm speedo. You have three remedies
to this scenario. 1) Drive by your tach. 3250 rpm is 55 mph, and 2600 is 55
in o/d. 2) Change your speedo to the 1000 tpm from a 75 - 76 car, or midget,
3) change the o/d speedo gears. This can be done in the car by removing
output flange, seal, and using a wire to fish out the drive gear after first
removing the pinion. You have to replace both the pinion and drive gear and
this will cost you a couple bucks.
Eric
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