I know this is going to be a shock to all you raised in the internet age, but engineers used to get all their information from printed paper books. They were called "catalogs". And one of the reasons an engineer would choose one manufacturer's catalog over the competition was the application and engineering information, usually in the back.
Believe it or not every engineer had his own library of his favorite catalogs. Larger departments maintained a "catalog library". You knew you were in the presence of an old machine designer by the condition (and sometimes the smell) of his catalogs. So many names come to mind: Browning, Morse, Boston, Tru-Arc, Parker, Shaefer, Vickers, SKF, Torrington, Timken, Dodge, Aero-Quip, Gast, Bimba, Tolo-Matic, Nook, Carr-Lane, and of course the old stand-by: McMaster-Carr.
Talk to a real live person at the timing belt manufacturer, preferably one in applications engineering. They can send you all the information you need.
As a side comment, it absolutely amazes me how often I have to give that same advice: "talk to a live person at the manufacturer". It seems so intuitive to me, so natural, so instinctive. I would never dream of asking a bunch of folks I don't know for design advice on a system for which I know there is at least one live person whose job is tell me everything I need to know about it, and whose job depends on making the product in question a success.
What does that indicate? The modern generation doesn't even consider initiating communication that doesn't include a computer or I-phone screen somewhere in the path? Just the ramblings of an old curmudgeon.