Reverse rotation mechanical fan

diesel_lv

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'67 Coronet w 496, about 610hp in 110-120° typical daily summer temps. Waiting for Derale 6 blade steel reverse rotation fan. Will be direct mount, no fan clutch, and using the factory shroud. I have dual electric fans that do great at low speed n idle. But at highway, gets up to 220 on flat n level. Tried 2 radiators, 2 row 1" aluminum and 2 row 1-1/4" aluminum. 180 and 160° robert shaw thermostats, flowkooler water pump, sheet metal shrouding above, to the sides and below the grill to core support funneling all air through the face of theradiator. My idea is that the electric fan shroud is a bottleneck. Hoping the mechanical fan n stock shroud will work. My question, just in case, does anyone know of a 7 blade just like the factory reverse rotation fan. Im getting a new water pump pulley for my serpentine pulley setup that will replicate stock pulley thickness so I can run mechanical fan. Maybe even a fan clutch. I've looked at a modern plastic reverse rotation fan but would need to research fan clutch fitment. Thanks in advance.
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493 Mike

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Does your electric fan shroud have the by-pass flaps I have seen on other shrouds?
Mike
 

diesel_lv

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Does your electric fan shroud have the by-pass flaps I have seen on other shrouds?
Mike
Yes, I put 10 2" diameter holes w rubber flaps in it. The e metal shrouds is the shape. They are flat. Not conducive to creating a negative pressure behind the fans. The stock shroud is a funnel and tapers a little like a venturi creating a low pressure to help draw air.
 

Don Frelier

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Perhaps apples an oranges.
I've never driven mine in those high temperatures. But my 383 will run below 190 at highway speeds with no fan at all even with ambient near 90.
Cheap eBay aluminium 22" radiator.
Just an FYI.
 

diesel_lv

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Perhaps apples an oranges.
I've never driven mine in those high temperatures. But my 383 will run below 190 at highway speeds with no fan at all even with ambient near 90.
Cheap eBay aluminium 22" radiator.
Just an FYI.
Ya, at 90° my 496 will run at 195-200. But that limits me to 6 months out of the yr for driving.
 

Don Frelier

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I'm thinking yours should be able to do the same at 90 degrees run near 185
 

Cranky

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How wide is the radiator you're using? The opening in my 66 Belvedere is only 22'' and it's a factory ac car. I'm planning on opening it up all the way to the frame rails if possible. That will give me nearly 10'' more width (the pinch weld flange is gone and solid welded)....figure if it won't cool with a 30" wide radiator, something's wrong. Have you tried a restrictor plate instead of a stat?
 

diesel_lv

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How wide is the radiator you're using? The opening in my 66 Belvedere is only 22'' and it's a factory ac car. I'm planning on opening it up all the way to the frame rails if possible. That will give me nearly 10'' more width (the pinch weld flange is gone and solid welded)....figure if it won't cool with a 30" wide radiator, something's wrong. Have you tried a restrictor plate instead of a stat?
It's a 26" radiator, factory a/c w shroud. I agree it "should" be able to run 185 in 90 ambient.
 

68 Sport Satellite

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'67 Coronet w 496, about 610hp in 110-120° typical daily summer temps. Waiting for Derale 6 blade steel reverse rotation fan. Will be direct mount, no fan clutch, and using the factory shroud. I have dual electric fans that do great at low speed n idle. But at highway, gets up to 220 on flat n level. Tried 2 radiators, 2 row 1" aluminum and 2 row 1-1/4" aluminum. 180 and 160° robert shaw thermostats, flowkooler water pump, sheet metal shrouding above, to the sides and below the grill to core support funneling all air through the face of theradiator. My idea is that the electric fan shroud is a bottleneck. Hoping the mechanical fan n stock shroud will work. My question, just in case, does anyone know of a 7 blade just like the factory reverse rotation fan. Im getting a new water pump pulley for my serpentine pulley setup that will replicate stock pulley thickness so I can run mechanical fan. Maybe even a fan clutch. I've looked at a modern plastic reverse rotation fan but would need to research fan clutch fitment. Thanks in advance. View attachment 990057
Are you set on a 7-blade? I have a Mopar Performance 5-blade Viscous setup with mounted Hayden Fan Clutch that I bought in error last year. It's reverse rotation compared to what I needed for my big block 400 B motor. I had no idea at the time. I've got it in a box and just to try it would be happy to ship to you if you pay shipping from San Jose, CA. You would just need to source the correct belts. Send me a PM if interested.
 

68 Sport Satellite

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Also, is your timing tuned well? Can't adding a bit of timing sometimes help with overheating?
Another thing to try - BUT LET's NOT START DEBATING THIS JUST YET - JUST SOMETHING TO TRY - if you're running your carb vacuum advance, hook it up to the manifold vacuum port instead of ported vacuum. There are pros and cons of each, but I've found if vacuum advance is hooked up to manifold vacuum, the motor tends to run cooler (timing influenced). Many will say no it's supposed to hook up to ported vacuum, but it worked for me on my previous 360 LA motor.
 

diesel_lv

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Are you set on a 7-blade? I have a Mopar Performance 5-blade Viscous setup with mounted Hayden Fan Clutch that I bought in error last year. It's reverse rotation compared to what I needed for my big block 400 B motor. I had no idea at the time. I've got it in a box and just to try it would be happy to ship to you if you pay shipping from San Jose, CA. You would just need to source the correct belts. Send me a PM if interested.
I'm not stuck on anything yet. I'm just looking for a 7 blade in case. But I found that the 11 blade plastic severe duty fan that I posted at the beginning will mount to a severe duty reverse rotation fan clutch. Waiting for my new billet pulley to see what my distance from pulley face to radiator is. If it's 3.75" or more, I'm golden. Then it's just seeing if the factory fan shroud creates enough negative pressure and allows enough airflow at highway speeds to keep the engine at or below 200.
 

diesel_lv

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Went to start my car for the 1st time today. 6:30 pm parked in the garage. Going to get tacos n beer. No need to warm up the engine.
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Cranky

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Went to start my car for the 1st time today. 6:30 pm parked in the garage. Going to get tacos n beer. No need to warm up the engine. View attachment 990350
Yesterday we got a break when a 'cool' front came through. Morning temp was 72 at my place and my bike ride in just a T shirt and shorts felt almost too cool but the afternoon got warm but was 6 degrees cooler than the day before. Now we're looking at a couple of tropical waves heading towards the Gulf of Mexico. I'd sure like to move away from the coast a bid....
 

diesel_lv

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Might be fixed. A few more runs to make sure. Drive 50 mile round trip w a 10 mile 7% uphill grade in the middle in 110° temps at 70mph/2700 rpm. Engine hit 201° and needle in middle of factory gauge but mostly stayed at 195° or below. Had a piece machined that eliminates the fan clutch, allows a factory, not flex, fan bolt to the water pump. Used a nylon, reverse rotation, 11 blade, 19" fan from a Chevy truck w a 496 and my factory shroud. At idle and around town it gets up to 195 but that is about it. A/C still blows cold at 40° vent temps. Im going to do a bit more testing, but so far it seems to be working.
 

diesel_lv

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20 miles at 60mph/2400rpm in 110° temps. Ran at 183-185. Way better than 210-220. But I truly won't know until next summer when I'm back in the 120's outside.
 

diesel_lv

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Final test for the summer, 10 miles of 7% grade at 70 in 106° temps. Stayed steady at 188° with the 180° thermostat. I'd say its working pretty good. Just have to wait till next summer's 120 degree days to get a final stamp of approval.
 

1 Wild R/T

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Excellent!! Pretty extreme conditions to try to keep a big engine cool in...
 
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