V-groove tensioner pulley

I'm looking for a way to take up the slack in my V-groove belt by adding a tensioner pulley. I really want to accomplish this with a spring loaded type of pulley. I've tried taking up the slack with an adjustable pulley but it still seems to throw the belt off occasionally. I'm not sure if such a thing exists but I'd really like to fabricate some type of spring loaded v-groove tensioner. My project is not really model/make specific but if you must know it is going on an 1988 Astro van.

To make this thread real simple.... I'm wondering where I can find or what type of vehicle I can rummage through at the junkyard to find a v-belt pulley tensioner. Does such a thing exist?

Thanks for any help on this seemingly difficult project.

Why not just go to the parts counter and measure up a smaller belt?

:confused: