Don't confuse serpentine belts with ribbed belts. Every serpentine belt I' ve seen has been a ribbed belt, but that doesn't mean you need a serpentine blet with automatic belt tensioning devices, etc. if you are just connecting two pulleys, i.e. the engine and an alternator
. A simple ribbed belt is all you need.
One ribbed belt can carry more power than one v-belt, and dual v-belts inevitably fail because one carries more tension than the other, so one slips and the other bursts. They're obsolete, plain and simple. As are v-belts in cars, because one serpentine belt, running in one pulley system with one tensioner, is cheaper and more effective than multiple v-belts.
If you are still running any belt without an automatic tensioner (i.e. us fossils with v-belts) then invest $40-100 in a belt tension gauge and set the tension on that belt correctly. That is going to be way cheaper than replacing your alternator
pump because you over-tightened the belt and burned out the bearings with excess side load!
Sure, you can measure pulley distances and belt deflection and set tension by using rulers...but I've never seen anyone do that, they just use a thumb and say "that's ok" and inevitably, half of those are too tight because who cares if the alternator and water
pump burn out next year? The customer will just come back for more work, meanwhile they're happy. Right?
Aluminum pulleys are nice--but plain aluminum alloys will quickly oxidize in salt
air, and if you anodize the pulley the belt may wear it off. Bronze or steel
may be a better bet if you can't get a corrosion-resistant aluminum alloy in the right thickness, and the machine shop can lighten that by drilling lightening holes in the body of the pulley. I had one fabbed up from aluminum to get a custom diameter (and cut charging
time in half) and had to settle for alu and no lightening holes in order to get it done on time and on budget
. So...we ignore a little white powder and spray it with Boeshield once in a while.<G>