Belt size for 5.3L with both pulleys & factory 160-amp alternator?
 

Anyone here running this exact set-up and can tell me which Gates p/n to use for the alternator belt? Thanks in advance!

5.3L with factory 160-amp alternator (KW1) running both pulleys (SLP 25% underdrive crank pulley & ASP 32% overdrive alternator pulley)

A GM tech told me (CLICK) that the stock belt length for the 160-amp is 93.0 inches, which is 0.7 inches longer than for the "other" (100-amp???) that uses only a 92.3-inch belt.

The pulley manufacturers recommend which belt sizes to use, but I am under the impression that it only applies to the 100-amp alternators. So, because I did not major in Geometry, can anyone tell me if the 0.7 inch difference would still apply when using the pulley set-up I am describing above, or is there enough slack in the tensioner pulley to compensate for this difference? :confused:

I have those pulleys and I reused the same belt when I went to a larger alternator.

Here's what I can tell you. I just put a 145 amp alternator in place of my 105 amp alternator. The pulley on the 145 amp sits up higher requiring the longer belt. Some here have been successful reusing the 92.3" belt on the 145 amp alt, but I tried it and there was absolutely no way it was going on. So I bought a 93" gatorback. It is tight! 93.5" probably would have been a better fit. Hopefully it should loosen up a bit over time. But I've been driving it around the past couple of days with no issues.

I have a 250 amp alternator and use the stock belt. There is enough slack in the belt.

I appreciate the help guys! :rock: I just don't want to be stuck with the wrong belt during my cam change since it's my daily driver.

If it bothers you too much, then just get a belt .5" longer than what you have, to have on hand in case you need it. If you don't need it, take it back for a refund.