My speeo. reads high about 5-10 mph. Whats wrong with it? I don't think its is a kph gear because it has been stateside all it's life.

mt5507

 

Are you running stock tires. or tires that are equal to the stock size.

Shane Morton 78 280Z owner.

 

If you have made any changes as the others have mentioned, you can just change the speedo pinion gear on the end of the cable at the trans. Nissan has different gears ( form 16 teeth up) to compensate. One tooth change should probably do it.