Going to remove my ac components, and already removed my smog pump. I have underdrive pulleys.What belt size do I need? Or how would I measure reliably?
Run a tape measure or piece of ribbon or the equivalent around all of your pulleys in the correct route and measure that. You may still have to try a couple different belt sizes to get it right.
Not all UDP's are the same size. So lengths can vary based on brand. There's diagrams for belt routing with stock pulleys.
I see 82.7" online for no smog or AC. UD pulleys usually require a half inchish less, so most likely around an 82". I'll measure with string and report back when I take the AC out.