Speedo Cable Length

DAZ

Founding Member
Jun 7, 2002
180
0
17
Endwell, NY
Two questions I need help with, before I start tearing speedo Cable out of Car.
Current cable melted on headers!
1. What is the proper length speedo cable for 1966 Mustang V8 C4 Trans? I have a 5' and 10' available at local Autoparts store.
2. What is the proper gear tooth count to get a 140 Mph speedometer to read correctly with 3.89 Gears? I put in a 21 tooth speedo gear and it appears to be 10 to 15 Mph to fast at 30 MPH.