Just the opposite, At idle you don't want the belt to contact the sheave too tightly. The rpms will make the clutch close and grab the belt. The squealing you hear is the belt slipping on the clutch, too much pressure to glide, not enough to move. Also be sure that you clutch moves freely on the jackshaft.
If you have time to think, You're going too slow...
PROX2 600
EDGEX 700 "stolen pride"
XCSP 500
RAPTOR 660
1990 JEEP WRANGLER
KAWASAKI ZX6-R
POWERSTROKE DIESEL W/BANKS PERFORMANCE