Thinking of ditching my electric fan - talk me out of it - Vintage Mustang Forums
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post #1 of 24 (permalink) Old 06-11-2018, 09:16 AM Thread Starter
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Thinking of ditching my electric fan - talk me out of it

I've got a 65 with a fairly stout 306 - afr 165, custom cam, etc. My cooling setup is a champion aluminum radiator with electric fan and spal adjustable fan controller. Thermostat is 185. Fan comes on 60% right around 195 and turns off around 185 - the controller isn't that specific but it is close according to my temp gauge. No issues with cooling - system works fine and fan very seldom comes on while cruising. However, I think that is my problem as underhood temps are high. After shutting off the fuel boils out of the bowls fairly rapidly. I do have a 1 inch phenolic spacer under the carb.

I switched to this electric fan setup last Spring - prior I had stock setup with clutch fan and shroud. I do not remember having this problem. I think the combination of the electric fan not running and the shroud design of the aluminum radiator really restricts the flow of air into the engine bay.

I can adjust the fan to run more, but that brings up my second issue - it is loud... I sound like a Piper Cub on takeoff. I am thinking of going back to the clutch fan - of course I'd need to go back to the stock radiator too...kinda stinks.

thoughts? opinions?
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post #2 of 24 (permalink) Old 06-11-2018, 09:35 AM
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Why would you have to go back to a stock radiator?

But I don't think the electric fan setup is causing your trouble. It's normal for engines to heat up after shutdown. Plus a clutch mounted fan is really only spinning at low RPMs. Not sure why your engine is getting to the point of boiling off the fuel though.

This might be more trouble than it's worth, but how about putting another temp sender on the engine and run that to a fan controller hooked up directly to the battery (so it will run when the car is off). Set this extra controller to come on at say 210 (or something pretty high) and turn off at 190.

My thinking is that when the engine heats up after shut down, your fan will turn on and pull air into the engine bay until the engine is down to 190. Yes, it will be pulling air through the radiator that is also heating up right after shutdown, but that will cool down fast. That should help displace the hotter air in the engine bay.
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post #3 of 24 (permalink) Old 06-11-2018, 09:47 AM
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I went with a Griffin Exact Fit aluminum radiator and stock fan, clutch, and shroud. Works perfectly but engine is stock. Couldn’t be happier with the setup though.


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post #4 of 24 (permalink) Old 06-11-2018, 10:23 AM
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I had a very similar experience with my '66. I had the phenolic spacer and found restarting after something like 20 minutes difficult. It was acting like it was flooded. I then replaced all the under hood fuel lines with steel, which didn't make much if any noticeable difference. I also moved the electric choke to its most lean position. I considered doing what Dan suggested, leaving the fan powered directly to the battery. That makes sense to me that it would help with the high under hood temps (I'm sure it's because of the shorty headers). But before I did that I put in a higher grade of gasoline. Went from 89 octane to 91. It has made a big difference. So much so for the time being I'm going to leave it as it is and see how it goes this summer. But with temps already in the high 90's its looking good.

Gasoline ain't like it used to be methinks!

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post #5 of 24 (permalink) Old 06-11-2018, 10:43 AM
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Edit to my last post.... I would have moved the relay trigger from a switched 12v to a constant 12v just to test the effect of having the fan run longer.

'66 Coupe: GT40 5.0: 670 Holley & Edelbrock RPM AirGap: JBA shorties: AOD w/TCI shiftkit: Granada Disks: R&P steering: 3.55 Currie
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post #6 of 24 (permalink) Old 06-11-2018, 10:49 AM
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Based on my experience with an electric fan in Texas (dang man, it's really hot), I can't imagine that the electric fan itself is causing your issues. It could be the way it's wired or fan controller or something, but mine works great, and it's just a cheapie from O'Riley with a Painless fan controller on it.

Between it's cooling performance and efficiency (no drag on the engine), I'll never run a mechanical fan again.
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post #7 of 24 (permalink) Old 06-11-2018, 11:08 AM
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Quote:
Originally Posted by BlakeTX View Post
Based on my experience with an electric fan in Texas (dang man, it's really hot), I can't imagine that the electric fan itself is causing your issues. ..
I agree completely. The OP's issue is with fuel boiling after shut-off and not directly related to cooling although he could setup the fan to continue running after shut-off to dissipate some of the under hood heat. Maybe that would help, or maybe not.

Other ways to remove heat from under the hood; ...louvered hood?...wrap headers?...fender scoop/vent?
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post #8 of 24 (permalink) Old 06-11-2018, 11:37 AM
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...or ceramic coat your headers if they aren't already? +1 on the hood scoop or air gap at the back to let air escape and making your e-fans run on a little after shut down.

I've always wanted to craft some kinda shaped thin aluminium heat shield, bolted like a gasket below our carbs like to deflect engine heat around the carb as it rises. It'd be ugly but may reduce that heat soak fuel boil over problem?
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post #9 of 24 (permalink) Old 06-11-2018, 12:04 PM
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Quote:
Originally Posted by Fishfreq View Post
...or ceramic coat your headers if they aren't already? +1 on the hood scoop or air gap at the back to let air escape and making your e-fans run on a little after shut down.

I've always wanted to craft some kinda shaped thin aluminium heat shield, bolted like a gasket below our carbs like to deflect engine heat around the carb as it rises. It'd be ugly but may reduce that heat soak fuel boil over problem?

Carburator heat shield





There are various different configurations of the plate.



It isn't mine so I have no idea how well this works.


I put the phenolic spacer on and it helped but didn't completely solve the boiling gas issue. I have the line from my side fender panel to the carb wrapped in thermotec heat shield and then I put that in a black plastic loom to make it look a bit neater. It has solved my carb heat problems but just barely.

My idle runs up if I've been running out on the highway so the fuel is hot enough that it is getting thinned out. It is somewhere just below boiling but it doesn't boil.
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post #10 of 24 (permalink) Old 06-11-2018, 01:17 PM Thread Starter
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Thanks for the replies.
My tri-y headers are ceramic coated, although several years old. The fan controller does run the fan 30 seconds after shutoff and I can adjust it to come on at any temp. I am going to play with running more.

I don't think it is just the fan, but the fan/shroud combo. It is shallow mount fan that is very close to the radiator, I believe it is 16 inches in diameter and the shroud completely blocks off all airflow except for that 16 inch hole. So my theory is, while this is great design for cooling the radiator it severely limits underhood airflow even while cruising.

I've got the larger radiator, so I believe my fan/clutch combo will be too long.

When I hit the different engine components with my IR gun they seem reasonable though. Carb bowls are around 140d (they were 157d before the phenolic spacer). Headers are around 215d, so the ceramic must still be ok.

The other thing I am also looking at is fuel. I still have some winter 93 in the tank... I may need more octane.

My symptoms are not severe, the car will start up after sitting and heat soaking. It does idle a bit rough for about the first five minutes of a hot restart, then it is ok. I do feel like I am a bit down on performance though. I've got a clear gas fuel filter right before the carb inlet. When hot, it looks like there is barely any fuel in the filter, but the bowls seem to be at the right level. When cold, that fuel filter is full.

The car is being used in a wedding this weekend, which will require me driving it about 1.5 hours away, so I am a bit paranoid.
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post #11 of 24 (permalink) Old 06-11-2018, 03:24 PM
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If you do decide to go back to a clutch fan this is a low profile one. I have it on my 65 Mustang.
https://www.haydenauto.com/upload/Ha...ch%20Flyer.pdf
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post #12 of 24 (permalink) Old 06-11-2018, 03:29 PM
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Dakota has a fan controller that can be set to run the electric fan for a set amount of time, after engine shut down. summitracing has those. About $100
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post #13 of 24 (permalink) Old 06-11-2018, 04:27 PM
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Quote:
Originally Posted by Dan Babb View Post
Plus a clutch mounted fan is really only spinning at low RPMs.
Um, that's a good thing. When we lived out in the country, my Dad removed the fan from his daily driver to save gas. Since he was never in traffic, he didn't need a fan.

Far from talking the OP out of switching back to the thermal clutch fan, I'd recommend doing it. Dunno why it would require a radiator change, though.

Amateur restorer. Well, sometimes I have been paid for it. But not right now.
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post #14 of 24 (permalink) Old 06-11-2018, 04:54 PM
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Keep the electric fan and the better rad. Maybe invest in one of the DCC or auto cool guy fan relay setups. PWM and soft start features make it easier on the alternator and charging system, plus they don't just SCREAM the fan on and then kick it off. They come on in a nice linear manner. The one in my GLH works flawlessly and I've ordered one for the Stang now too.

Figure out why your fuel is boiling off. Theres got to be another issue there.

I've seen quite a few mechanical fans come apart in spectacular manner in the last couple years....
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post #15 of 24 (permalink) Old 06-11-2018, 05:31 PM Thread Starter
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Update - my mechanical five blade clutch fan does fit!! It is tight, I have just .5 inch between the radiator and fan. I swapped out the electric for the manual fan. The original shroud does not fit on the bigger aluminum radiator (at least without some fabrication), so I am running shroudless.

20 minute drive in 90 degrees and I can tell a difference. The temp gauge stays pegged on 185 whereas with the electric fan it would creep up and down a bit. I have a Dakota Digital dash with electric gauges, so they are fairly accurate.

Hit the carb bowls with the IR thermometer after the drive while idling - 133d. Fairly big improvement. Does not seem to be boiling out either. I need more drive time to truly access, but so far I really think the my electric fan shroud design is not very good and is the cause of the underhood heat. It just doesn't let any air by unless the fan is on. To that point, I have seem some electric fan shrouds that have flappers on them in the corners that let the air by when moving...my did not have these.
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