I did a search and found a bunch of info, but no conclusive answer to my question.

I am about to install a serpentine system from an '89 RS on to my '82. I will not be using the AIR pump or an idler pulley.

Using the otherwise origional routing, what length belt will I need?

 

Not sure, but if no one answers, here is some advice someone gave me. Use a piece of string or something and run it through the way you plan on running your belt. Afterwards, measure the string, this will get you a good estimate of what you need. Buy a belt(make sure you can return it if it doesn't fit) close to the length of the string and see if it fits, and go from there. Might take a couple visits to the autoparts store, but should work.

 

I do not understand how you will be able to tighten the belt without the idler pulley as the idler is spring loaded and is what a serpentine system uses to keep tension on the belt. The accessories do not have adjustments to tighten the belt, as in V-belt drives.

 

What I meant is that I will not be replacing the AIR pump with an idler pully. The tensioner will remain intact.

 

then that will work, sorry for the confusion

Do the string method if nobody has a quick answer

 

No problem, I guess my first description was a little confusing.

Anyway, if no one knows (I hope someone does) then I will use the string method and post my results.

But I'm still hoping that someone else who had to make 4 trips to the parts store will remember and save me the trouble.