Just to follow up my previous posting about the GM Performance Parts Catalog Serpentine kits for the SB...you one stop shopping solution for all new equipment.
(1) This kit goes on a C3 SB with no problem. The idler bracket has to be mounted upside down to avoid interference with the passenger's side spring tower. This just shifts the location of the idler pulley that's no problem at all. As I related before,if you buy the kit PS pump, you have to buy a few dollar brass adapter to go from metric to english for the high pressure outlet.
(2) One of the passenger's side cast aluminum bracket mounting holes doesn't correspond to a cylinder head mounting threaded hole...it's probably missing on your SB. Instructions say to just ignore this. I did and no problem many years later.
(3) Pulleys...The 1990, 1991 Camero, Firebird which the Serpentine kit is a duplicate of, has pulley diameters that drive the water pump, PS, and alternator at relatively high rpms. This is for these street cars that may experience idling in hot weather with the AC on. AC on means a lot of electricity demands, the electric fan, maybe the headlights on, etc.........I bought March billet specialty aluminum pulleys to underdrive all my accessories. I wanted to avoid as much as possible the water pump, alternator, PS, parasitic drag on my engine. Also the March aluminum pulleys look great. The underdrive pulleys basically work out just fine. However, at idle at about 600 rpms, the electric fan gets into the battery. At idle, I have to keep the engine about 1000 rpm to keep out of the battery....a little more with headlights on..of course for a few minutes at a stop light, using the battery a little is no problem. I power my fan directly off the alternator..not the battery.
(4) Love the appearance of the Serpentine and the ease of maintaining it..it keeps itself in tension for all the accessories. However, as I learned with my 96 Tbird DD, if you loose your serpentine belt on the freeway...you're dead in the water. When the serpentine belt on my DD broke, I could get a little more driveability out of the car since I had pure ethylene glycol coolant in the engine. Because ethlene glycol boils only at an extreme high temperature, I could drive the car off the freeway without damaging the engine. My 68 SB ZZ4 has 100% ethylene glycol in the cooling system. My 97 DD Cadillac Seville has 100% ethylene glycol in the cooling system also. Still have 50/50 Dextrol in the 08.
