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Old 04-17-2010, 04:29 PM
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DAVID GAGNARD DAVID GAGNARD is offline
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Join Date: Jan 1999
Location: MARKSVILLE,LA.,,
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You definetly have under drive pulleys, I'd get rid of them ASAP.......They only compound the heating problem.......If you talk with any tech guy from any radiator manufacter or water pump manufacter with a problem, the first question they will ask is" do you run under drive pulleys"?????, if so,get rid of them, try it again then call back........under drive pulleys are recommend for "race only" applications.........You'll never notice or feel the 5 to 8 hp they claim your saving!!!!!!!!!!!!!!!!!!!!!

You can get some stock pulleys from a junkyard, bead blast them and paint them any color you like or buy the nice polished alumimun March pulleys, but ask first about the pulley size......

For a Cobra with a limited size radiator and big block motor, I'd recommend the crank pulley be no less than two inches in diameter larger than the water pump pulley....that way your over driving the water pump at low speeds and flowing a greater volume of water thru the motor/radiator......

10 years ago I had them (under drive pulleys) on my 65 fastback, had problems in city driving, tried 3 different radiators and maybe 5 electric fans (pullers) and added an electric pusher up front, it all helped, but never to my satisfaction till I started expirementing with varouis size pulleys..

What I found was the minimum I could run in city driving without constantly looking at the temp gauge was pulleys of the same size, then my water temp would creep up to about 210, once moving it would quickly drop back to 180......right now my crank pulley is 1.50 inches in diameter larger than my water pump pulley and I have a Griffin alum. radiator, 31 inches wide, 19 inches tall with a 19 inche diameter Caddy electric fan.....the car has done numerous parades, mostly Forth of July when the outside temp was 100 degress, it'll idle and stay on 180 for about the first 30 minutes, after that, it starts creeping up and takes about another 15 to 20 minutes to get to 200/210, which I can live with a couple of times a year in parades, once the parade is done and I get on the road at any speed above 40 mph, it'll cool back down to 180 in about one mile!!!!!!!!!!! all this is in a 65 fastback, 351-W, 350 hp.........

I have my electric fan on a manuel switch and on the highway or at speeds of 40 mph or above, I don't have to turn the fan on at all, only in stop/go/city driving do I turn the fan on...

David
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