I have a 1982 xj6 series 3 4.2 l6.
The speedo only goes up to 85 mph, can anyone tell me the peak output of this car and the redline rpm. I don't want to hit the freeway and over work the car

 

Best I can tell is


Power at 4500 RPM 134kW (180 bhp)
Torque at 3000 RPm 314 Nm (232 ft-lb)
Specific Power output 0.68bhp/ci, 41.6 bhp/litre
Max recommended engine speed 5000RPM
Max power output at 4500RPM


It's an engine, it will let you know when you are hurting it. You will feel the power drop off.
Enjoy.

 

Yes, and the power drops off because you're floating the valves.
(';')

 

Get a used 140 mph speedo. Plugs right in. I had an 85 in my 1982. Changed it as it was embarrassing.

 

I swapped the 85 out for a 140 on my old 82. The dash seems more synchronized, needles on tach and mph float in same spots with the 140.