The car runs and drives fine, its that the speedometer never tells you the right speed. the engines makes more power than stock. about 560. could this throw off the speedometer? is there any common problems that this could cause?

Any experience and help is greatfully accepted.

Thank you!

 

No.

The speedo is driven off by a gear in the transmission.

Different wheel and tire sizes are the most common issues of speedos reading incorrectly.

The one in my Dart reads about 5 mph fast but works up to 120.

 

rookie -

There's a speedo gear in the transmission. The gear ratio you need is based on rear end differential (gearing) and tire diameter. Swapping the gears is fairly easy on a 727.

A quick internet search should give you the chart to match diff gear ratios, tire size and speedo gearing.

Archer

 

if odometer is correct then the speedo needs a rebuild