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Discussion Starter #1
My 68 RS has a Morgan and Son 383 stroker with Hi-tech efi with 700r4 vintage air, serpentine system.

My issue is I cant keep the car under 215 in Ok summers even without the air on setting in traffic. Driving down the road is fine of course even with the ac on. I currently have a Be cool 2 core single pass radiator with a single 16 inch fan with shroud and a 185 thermostat.

I now the Ron Davis Radiator will do the job but that's a hole lot of Benjamin's for a radiator. Any suggestion?

Motor is a Morgan and Son 383 stroker with a large cam and solid lifters, fitech efi, elderbrock heads , water pump and intake.
 

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If the car cools when driving down the road then the radiator isn't at fault. You need more air going through the radiator at idle.

I recommend the stock for 1971 seven blade mechanical fan (stock Chevy V8 fans are 18" in dia.), and a fluid coupled clutch to drive it. I actually recommend a Flex-o-Lite standard duty thermostatically controlled fluid clutch, but they stopped making them due to the popularity of electric fans. Stant still makes a HD fan clutch for your application. That will move enough air at idle to keep your motor cool. If not you need to look at your ignition timing.

Big Dave
 

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Isn't an electric fan more efficient at idle? Its a 3300 cm flex light fan. I will admit the shroud doesn't cover the entire surface. I have looked at dual fans with shroud that cover the entire radiator but they pull less cfm's than what I have now.
 

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I had a similar problem with my Spal electric fan then tried several mechanical Flex fans without much improvement. I'm now using a 7 blade GM mechanical fan without a clutch, that solved the problem.
 

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Discussion Starter #5
Thank you both for the comments. Never thought I would have to go back back to mechanical. Better than the other 1500 hickey for a Ron Davis that I know will cure it.
 

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Mark VIII or Taurus fan, they have 2 speeds and both flow 4000+ cfm.

Check Ebay. ;)
 

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Your radiator is fine. With a better fan than the single 16” and a proper shroud should solve your issue. A single 16” has about 50 sq in of area where a dual 11s have approx 70 sq in of area.

Also depends on the cfm the fans are pulling. The Spal 16” pull anywhere from 1400 to 2500 cfm depending on the model. A dual 11” about 2700 cfm and dual 12” almost 3200.

I would 1st determine what fan you actually have and the cfm spec. Then go from there.

Another thing is your coolant mix. If 50/50 then not the best for cooling and overkill for antifreeze. It will run cooler with 30% coolant and 70% purified water.
 

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I tried this setup. pic. below. drove about 7 miles open road at 55-60 mph and would not cool. it went to 230*
come home and replaced it with a derale heavy duty stainless 16" 6 blade belt driven fan.
engine runs 180* all the time. this is a 10-8-1 compression engine
 

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I tried this setup. pic. below. drove about 7 miles open road at 55-60 mph and would not cool. it went to 230*
come home and replaced it with a derale heavy duty stainless 16" 6 blade belt driven fan.
engine runs 180* all the time. this is a 10-8-1 compression engine
It's because you didn't have any radiator hoses hooked up. Lol
 

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Moved thread to heating and cooling forum.
 

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Discussion Starter #13
I did verify the fan was a flex o light and the best I could tell from reserching the fan it's 3000 to 3300 cfm. Most dual fans I have seen are around 2700 cfm. I called Be Cool since it is there radiator and their dual 11" fan set up was around 2500 cfm. I didn't think having that much drop in cfm woulndt help me even if it covers more of the radiator.

Thanks for the pic. The mechanical fan seems to be the consences from most
 

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I have a Mark VIII fan on my 67 with a built 400 sbc and Champion radiator. My fan shroud covers the entire core. Works great! Never even switches to high speed. Fan motors are still available through chain auto parts stores.
 

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I did verify the fan was a flex o light and the best I could tell from reserching the fan it's 3000 to 3300 cfm. Most dual fans I have seen are around 2700 cfm. I called Be Cool since it is there radiator and their dual 11" fan set up was around 2500 cfm. I didn't think having that much drop in cfm woulndt help me even if it covers more of the radiator.

Thanks for the pic. The mechanical fan seems to be the consences from most
Don’t place too much faith in cfm numbers. Lots of variables in testing can affect the number. Sort of like car stereo amplifier power ratings...

Don
 
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Don’t place too much faith in cfm numbers. Lots of variables in testing can affect the number. Sort of like car stereo amplifier power ratings...

Don
Verify that it is turning in the right direction. I’ve seen more then one wired backwards.

X2. You really need a shroud that covers the entire radiator core.

Going back to mechanical imho is a step backwards. Electric fans have been used on almost every car manufactured for the last 20 years.
 

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I tried this setup. pic. below. drove about 7 miles open road at 55-60 mph and would not cool. it went to 230*
come home and replaced it with a derale heavy duty stainless 16" 6 blade belt driven fan.
engine runs 180* all the time. this is a 10-8-1 compression engine
Avoid shrouds like this, they kill air flow.
I use a two speed electric fan and shroud from a late 90’s thunderbird (cougar) V8. Cools a pretty stout SB2.2 in any conditions we get here in the NW. Factory style shrouds are key, they promote flow as opposed to restricting it.
 

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I would go with a GM 7-blade fan with a thermostatic clutch too. I would also fit a factory-style shroud.

I would not go to a 160° thermostat. A 180° thermostat would be fully open by 200°F so your 215° temperature in traffic means that there isn't enough airflow to keep up with the heat the engine is producing.

Make sure that there isn't any scale in your cooling system. An acid flush (oxalic or citric) does a great job in removing rust and scale without harming aluminum or copper/brass. See Cooling System.
 

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Discussion Starter #20
Thanks guys! Lots of great ideas. I think I'm goinf to start with rhe Mark VIII fan if I can find one. Will post results when I have made the swap
 
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