I recently bought a 55 Chevy with an 8-71 blown big block. The engine runs strong through all RPM ranges and has no issues. The blower belt seemed to extremely loose so I contacted Littlefield and was told to adjust it for about 3/4" of play between the top and bottom pulleys when cold. When I do this I get a "ringing" sound that seems to be coming from my alternator. This is weird since the alternator is driven by a serpentine belt that runs off the crank pulley and has nothing to do with the blower drive. At first I thought maybe the blower had a bad bearing in the snout, but the sound doesn't seem to be coming from the blower. I've checked the belt tension when hot and there's still about a 1/2" of play so I don't think the belt is too tight. If I loosen the belt up to about 1" of play the sound goes away. I've also noticed that the blower doesn't have a great deal of whine while driving the car. You can hear it if you give it gas while sitting, but there's essentially no whining sound while driving. Has anyone else experienced anything like this?
Half an inch hot seems tight, it will loosen with heat.
Also, you'd be surprised how much whine there actually is, I had a car follow me to a show n shine, he told me he could hear it from behind a block away, 8-71 on a small block, and that was only at about 30 mph; I didn't think it was loud at all. Keep in mind 1/2 inch pitch pulleys are louder than 8 mm, which are more round toothed, but mine are 8 mm.
Half an inch hot seems tight, it will loosen with heat./QUOTE]
Did you mean to say it will tighten when hot?
When the motor heats up it will cause the belt to get tighter. Metal expands when it gets hot. Too tight is bad, will put more strain on the snout and lower pulley. Better to run the belt on the loose side than too tight.
The whine from the blower is caused by the belt tension. There is a theory about escaping air between the belt and the pulley. The tigher the belt, the more louder the whine.
Not sure about the alt sound, that is a new one for me.
I've never had my belt go loose, but assume, along with the pulley, the belt would get hot as well, expanding. Maybe that's not the case, I"m not willing to test my theory...
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