serpentine belt tension (w/o tensioner pulley)

My 1987 GMC p/u/ w/454 has a serpentine belt with no tensioner pulley, of course. How tight should it be? I know that it should be tighter than v-belts, but how much play should I leave? 1/2 to 1 inch on v-belts, MUCH less on serpentine? THANKS- Spender (John)

The way Honda taught was, after adjusting you should be able to twist the belt 90 degrees at its longest section. if you cant loosen if it twists too far tighten.