HI i have noticed that my kickdown wire is not hooked up on my th400 is it true if i wire up kickdown and throttle is floored it actually ups the line pressure? or does it just kickdown a gear at normal line pressure ? trans has allway perfomed well at drags running low 11 secs ,if it does up line pressure will it help when i hold it down and shift gears manualy its a th400 built by b&m
thanks
victtor
new zealand

It is not true that the kickdown raises line pressure. When you floor it, this decreases vacuum going to the modulator, the reduced vacuum raises line pressure. Line pressure on a 400 is controlled through the modulator & pressure regulator valve in the pump. If you are satisfied with the way that you are currently running it, then there is no reason to mess with it.

Please note:
The electic kick down switch open a solenoid in the valve body which causes the modulated pressure to go higher than it would with the vacuum modulator control alone. This higher modulator pressure is sent to the shift valves and the pump boost pressure regulator valve. This causes the shifts points to rise (about 600RPM higher on my car) and causes the line pressure to rise.
If you want higher line pressure when you leave the line, put the car in 1st or 2nd gear. This activates a different oil circuit to the boost valve which raises the line pressure above what it would be with detent pressure.
RJ

Also the kickdown wire really only has an effect if you want the car to shift higher while leaving the shifter in drive.Then it relies soley on the governers to shift.