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Question: Correct Fan Belts?

I have a 1990 Southwind 28' motorhome. VIN #1GBKP37N4L3300798. It has a 454 with TBI, A/C, and no A.I.R. pump. It is on a Chevy P-30 chassis, but is the variation used for motorhomes. There are 4 "fan" belts on the 454 engine. Counting the belts from the front of the motorhome, I have been trying to get the correct part numbers or specs for belts 2 & 3. These are the 2 belts that drive the dual pulley A/C compressor. There is a short belt that goes around the forward A/C pulley and the PS pulley and is approximately 37". There is a longer belt that goes around the A/C rearward pulley, the fan pulley, the crank pulley, and the PS pulley and it is approximately 60.5".

I don't have the old belts and have been experimenting with various combinations of belts I obtained from the local NAPA store. The belts only vary by 1/2 " diameter but I can't get the right combination. When tightening the belts with the A/C adjustment bolt, the belts don't tighten equally because of their different diameters. When one of the two belts is tight, the other is too loose and you get the screeching sound of a loose belt. The NAPA belts only vary by 1/2" in diameter but that is enough to make a difference in which belt tightens first.

I have the official "Chevrolet Motor Home Chassis Guide" and it lists the two belts as 60.5"(x 3/8"w) and 41"(x 3/8"w) . I have tried the combination of NAPA #7603(60.6") and NAPA #7374(37.75"), but when the longer belt is tight, the shorter belt is too loose. This would seem to rule out the longer 41" belt shown in the service manual.

The GMC service hotline referred me to the local Chevy/GMC dealer. The local Chevy/GMC dealer was of no help. NAPA has listings for the 454 on a P-30 chassis but it usually excludes motorhomes or has an A.I.R. pump configuration.

Perhaps someone has this chassis/motor combination in a 1988-1995 Southwind or Pace Arrow and can actually look at the belt part numbers in their engine.

Bill Bevan
bgbevan@earthlink.net