Belt Help. Going from 3.5in to 3.25in pulley

[vladSVT]

Need help figuring out what belt to run.

Current belt is napa 25080839 (Which is 84.375in)

I have a 3.5 upper pulley.
Going to a 3.25 pulley, what belt, or how much should the belt inches decrease?

I was thinking the the napa 25080830 which is 83.5in and the next size step down. But thats almost an inch differnce, while the pulley is only .25 smaller...

Should I just run the same belt that I have on then? Or?

 

[mtdubvee]

Belt size

you need to run a string or tape measure around your pulleys just like the belt would go. Then subtract roughly a 1/2" from that total length to account for belt tension. Then find that size belt.

 

[racecougar]

It'll depend on where you're at in regards to the travel range on the tensioner currently, as well as how much belt wrap you have at the SC pulley. The actual change in length of the belt path will be ~5/8" or less depending on belt wrap at the SC pulley. Depending on where you're at in the travel range on the tensioner, you may get by with your current belt, or you may be able to fit that shorter belt.