Belt question

plstktnkr2

SCCoA Member
I have installed an A/C eliminator pully on my S/C motor (DORMAN) and it has a pulley for a 130MM x 6 rib belt (which is wrong) and uses the stock belt.

But due to me only finding a 90mm x 8 rib pulley (ford power stroke) I need to know how much shorter the belt length for the proper fit.
I hope I explained it right
Rick
 
Difference in circumference is equal to the difference in diameter times pi. So you have (130-90)*3.14 = 40*3.14 = 125.6mm = 4.94". But I guess you need to factor that total difference in the pulley circumference by the percent of the pulley that the belt wraps around. I am just guessing the wrap is about 180 degrees, or 50% of the pulley. Then the belt length difference would be about 2.5". If the stock belt is 89.7", then you would need something around 87.2". That would be a Gates K080872, from a 2005 Freightliner. If you can't get that, you may be able to go up or down a little because of the range in the belt tensioner. But I would try to stay close.

Please check my measurements and assumptions before buying anything. Your mileage may vary. Optional equipment shown. :)
 
You're welcome! By the way, I found this thread with engine bay pics ... it seems like the belt wraps around the AC pulley just more than halfway. Maybe 55%?
http://www.sccoa.com/forums/showthread.php?t=128778

So that would make the difference closer to 2.7", if the pulley measurements are correct. If the 87.2" belt doesn't give enough tension, you may have an issue. The next size down that I see online is 85.9", which may be too tight. You may need to buy a different size tensioner pulley to loosen or tighten the belt a bit.
 
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