More thoughts on misc pulley sizes
I replaced my SC tensioner assembly last night, and put my oversized 3.5" idler back on the new one as I had before. Because of the added tension (the old one was weak), I have alot less clearance between the belt faces on that idler and the water pump now.
Today, I'm modifying my torque-axis mount to allow for my underdrive (10% larger) water pump pulley. I think I'm going to have to step down that tensioner idler pulley diamter to a 3.25" or 3.0" now.
FYI, on the Series 1 L67, the SC belt also drives the WP and the AC. Alt and PS are on the outer belt.