Quote:
Originally Posted by Singleton
I’m a big proponent of those stainless flex fans, they really move a lot of air at idle. Have a 19” on my 66 GTO, albeit with a large 8” water pulley and a small 6.5” crank pulley to slow the fan down in relation to engine rpm. Runs at thermostat temp in any traffic idle conditions in south Alabama summers.
But I would caution over-driving a flex fan using a small water pulley, which would make the fan spin faster than engine rpm. With my setup at 6000 rpm engine speed, my fan is spinning at less than 5000 rpm. If you use the small water pulley you will spin the flex fan approaching 7000 rpm at that same engine speed, so be aware of that aspect. When Pontiac used those flex fans they were under-driven with large water pulleys
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Good info. I’m running a 2.56 rear and a stock 350. Not much of a high RPM blast takes place. It’s a Saturday afternoon cruiser. I’ve tried two different fan clutches, fan positions, ported and full vacuum advance. Initial timing at 12 BTDC. Nothing changed the inevitable rise in temperature at idle and in a slow traffic (less than 10 mph) situation. Sort of my all in effort to keep this car a driver during warm weather without going all electric fan assemblies.