Torsion Bar

I would like to lower the front end of my '89 Small Bed P/U and I noticed that the front suspension is torsion bars. I was told that you can lower/raise a vehicle by turning the torsion bar. How do I do this? What way do I turn what to lower it?

I don't want to lower it alot, 1 or 2 inches.

Any help is appreciated.

Thanks DAVE