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Discussion Starter #1
Running a fairly stock 429 in my mark 4 Roadster. During build I used FFR radiator and fan ( without fan shroud). On highway driving coolant temperature was normal and only got hot when idling for long periods of time in slow traffic. So to correct this issue I installed a fan shroud and a filler plate between the top of the radiator and the body. Well, guess what it now runs at least 15 degrees F. hotter on the open highway than it did without the two items I added. I got mad and removed both items and it is now back to normal open road temperatures. Big question now is which one of the items I added caused the increase of operating temperature.

Has any one else experienced this condition and if so what was the cause and the cure?? If no one has any suggestions I guess the only thing to do is to install one item at a time and see what happens.

Oh, by the way after installing both items the cabin temperature also increased.
 

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What is your distilled water to anti freeze ratio?

Dwight
 

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I have a radiator that will cool it.
 

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Any possibility you reversed the wiring on the fan when you reinstalled it with the fan shroud?
 

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I have seen street cars where a post card size piece of the shroud (or two) is made from rubber sheet. This way either the fan, or higher road speed will push it open to allow more flow.
 

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Do you have any pictures of your shroud/fan setup?

Without knowing exactly what your setup is, what you're describing makes sense. Without the shroud you have less air side restriction allowing more air to flow through the entire radiator core while cruising or necessitating the fan to run. The shroud forces all the air to have to flow through the smaller fan opening. With the shroud you should have less issues at low speed since the shroud allows the fan to utilize more surface area of the radiator core (provided the fan is spaced away from the face of the core). Also, if the engine is running hotter and you have less air flow through the engine bay your will see higher cabin temps.

I'm not familiar with the specifics but I'm betting the stock FFR radiator/fan is probably marginal for a 429 that will likely have a higher heat rejection than the more common small blocks and coyotes. What temps were you running before and after the mod?

For what it's worth, if it we're me I'd probably swap the FFR fan for a better one and leave off the shroud. This in theory should solve your original problem without creating another or one.

Like Gordon said, the other option may be a more efficient radiator.

Just my two cents from the peanut gallery.
 

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Official OLD GUY
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429 issues

FORD's 429/460 is a known heat monster, always has been no matter what car its in.

I'd suggest that you get an appropriately sized radiator as that has always been the "fix" for 429/460 installs in the past.

Also, the air deflector above the radiator can sometimes cause less air flow around the engine, causing heat soak issues. Try running without it and see what your temps are compared to running with it.

FORD had an issue with the 1970+ 460 when they retarded the cam gear by 6° for smog law restrictions. The fix back then was to install the 1969 crank gear to lose the 6° retarded engine cam timing for more hP and less heat being generated.

Doc
 

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My Ford Racing 302 made too much heat for my stock Mustang radiator and shroud. After sweating many a long red light or train crossing, I bit the bullet and bought a FFR aluminum radiator and a breeze fan shroud. I left the larger electric fan on it. I never have any temperature problems now. If I am sitting a long red light, the temp may rise to around 195. Then the fan kicks on and the temp goes right down to the thermostat temp of 180 and stays there regardless of how long I idle. I think you need a larger radiator and a fan shroud.
 

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Discussion Starter #13
Doc,
The engine is a 1969 version so no smog issues here. The radiator I am using is the one supplied by FFR and it is a two row unit. Also using the fan they supplied. Going to do some research on radiators to see what is best. If I get time this week I may install the radiator shroud and see what effect it has on temperature. As I mentioned before no issues on the road, just in slow or standstill traffic. Thanks for the info.
 

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Discussion Starter #15
My Ford Racing 302 made too much heat for my stock Mustang radiator and shroud. After sweating many a long red light or train crossing, I bit the bullet and bought a FFR aluminum radiator and a breeze fan shroud. I left the larger electric fan on it. I never have any temperature problems now. If I am sitting a long red light, the temp may rise to around 195. Then the fan kicks on and the temp goes right down to the thermostat temp of 180 and stays there regardless of how long I idle. I think you need a larger radiator and a fan shroud.
The radiator is made by AFCO for FFR only. I just had a long conversation with a representative of AFCO and was assured the radiator was large enough for my application. This radiator needs lots of air to keep things cool and as I mentioned before driving on open road is no issue, just in slow or stopped traffic. His theory is when open road driving the fan shroud is restricting air flow across the radiator. Also, one of the replies I received mentioned that the filler plate is probably reducing air flow into the engine compartment thereby increasing temperature of the engine and cabin. All of this has been interesting. Thanks for the info.
 

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Your fan and shroud need to be an inch or so away from the radiator so the fan pulls air through the whole radiator. It also allows air to flow through the whole radiator at highway speed when you shouldn’t need the fan. The shroud does need to be sealed to the radiator. A picture would be helpful
 

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try 25% anti-freeze and 75% distilled water. You need anti-freeze for the freeze protection and corrosion resistance. You live in Northern Tenn and most likely keep your Cobra in the garage in the winter. Not much of a chance of the motor freezing. So 25% should work for you.

Water conducts heat better than anti-freeze.

Part of one of many article about cooling

"The specific heat capacity of ethylene glycol–based water solutions is less than that of pure water; in a 50 percent solution, ethylene glycol’s specific heat capacity compared with pure water is decreased at least 20 percent at 36 degrees and about 17 percent at 200 degrees. Propylene glycol, another common coolant, has an even lower specific heat. Assuming a 100-gpm (gallons/minute) coolant flow rate and an energy loss through the coolant system of 189.5 hp, the water temperature increase would be 10 degrees, the ethylene glycol water mix would gain 20 degrees, and propylene glycol would gain 33.3 degrees.
Compensating for the reduced heat capacity of coolant/water mixes would require circulating more fluid through the system. Assuming a fixed amount of circulating fluid and radiator capacity, running 100 percent water would be the most efficient coolant in terms of its ability to conduct heat with minimal temperature rise. In other words, of all common liquids, water requires the most heat energy to change its temperature."

https://www.hotrod.com/articles/glycol-or-water-coolant/

https://www.evanscoolant.com/blog/antifreeze-vs-waterless-coolantwhats-the-difference/

Hope this helps
Dwight
 

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Discussion Starter #20
Your fan and shroud need to be an inch or so away from the radiator so the fan pulls air through the whole radiator. It also allows air to flow through the whole radiator at highway speed when you shouldn’t need the fan. The shroud does need to be sealed to the radiator. A picture would be helpful
The shroud is from Breeze with 1 3/4" spacing of the fan from the radiator. Breeze made the shroud for a tight fit on FFR supplied radiator and fan. No pictures since I have already taken the shroud and filler plate off the car.
 
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