[roy green coupe]

While observing my running engine on my 30 coupe, I noticed the belt seemed to be going through a harmonic vibration at certain rpms.I first thought the crankshafts pulley was the problem as the belt seemed to run in and out some.I did notice the belt was rather loose and had been reluctant to tighten it not wanting to put excessive load on the water pump.I was trying to leave well enough alone but I overcame that and decided to order and install the brace for the generator and tightened the belt.I was surprised when the belt now seemed to run smooth and true on the crankshaft pulley .I was also able to notice the engine seemed smoother in high gear at speed.I have read where others have taken the belt completely off for a short test.I think think the high placement of the fan and water pump magnify their vibrations.I have wondered if slowing down the fan speed with different size pulleys would accomplish some of the benefits people talk about with overdrives.