High speed idle adjust? how and why?

[Deezul1]

What is the purpose of the high speed idle adjustment and what is to be gained by messing with it. The manual says by god dont mess with it so I guess I have to do it.

TIA

 

[R.ebel]

High Idle

It controls the RPM at which the govenor starts to pull the fuel back. On most '97 trucks with manual trans the high idle no load rpm is about 3400 rpm. My '97 would start to defuel at about 2750 rpm under load. If you cannot resist playing with the adjustment get the 60lb valve springs so you don't float your valves at high rpms. The govenor spring kit will also let you get more rpm.

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[Joseph Donnelly]

It is a high IDLE adjustment. Fueling will still be cut back where it was before, but under no load the engine will rev higher if you turn the screw inward some. The governor spring kit from Piers or BD will get you fueling for power at higher rpm.

 

[Deezul1]

Thanks Joe + Rebel

Thats what I need , a reason for not messing with it, it wont do me any good. Its always good to learn more about how these things work, Thanks again