Heat at Idle

Horsepower · Jun 30, 2008

Hey Board~ My '74 gets to 250*+ at idle, but when driving it stays at 180*.
I was thinking about stripping out the manual fan/shroud and adding the largest electric Black Magic fan I could find. I figure I'd keep it on whenever driving the Bronc. Any thoughts on this?

Details-
-fresh 302
-Waterwetter
-180* Therm
-brand new alum 4-core radiator
-hi-flow WH water pump

Thanks, Erik

justinoshea · Jun 30, 2008

thats how most new cars are. not cheap.

another option is an additional pusher fan in front with or without an automatic thermostat. depends on how much other crap is already there.

Idle is also the worst case for radiator air cavitation (hot exit air returning to front of radiator). seal all the holes, gaps, hood and use a good shroud. it will still have a path from the bottom, which is one reason why cars have engine belly pans.

bmc69 · Jun 30, 2008

Horsepower said:
Hey Board~ My '74 gets to 250*+ at idle, but when driving it stays at 180*.
I was thinking about stripping out the manual fan/shroud and adding the largest electric Black Magic fan I could find. I figure I'd keep it on whenever driving the Bronc. Any thoughts on this?

Details-
-fresh 302
-Waterwetter
-180* Therm
-brand new alum 4-core radiator
-hi-flow WH water pump

Thanks, Erik

I did that experiment when my truck (408) was behaving exactly as you described..it failed, the expensive Black Magic sitting on the shelf now. I gained a barely noticeable improvement in how long it took to overheat at idle..but it created a new problem; overheated at highway speeds too, where before that was when it was always fine...as with yours.

The right mech fan and shroud combo fixed it for me..large 7-blade fixed pitch fan from an F-250 460 Camper Special with fan clutch. I added a SPAL electric pusher in front of the raddy and still need/use that when crawling rocks only, otherwise I'm golden without the electric.

Master Chief · Jun 30, 2008

Your gonna want to leave the fan shroud on it so the fan can create a vacuum through the radiator.

I would put in a hotter thermostat so the water stays in the radiator longer and make sure your anti-freeze is mixed properly. A clutch fan is good too, your gas mileage will be better since it ain't dragging on the engine at highway speeds.

Also, dependiing on how fresh the 302 is, it's gonna need some time to break in before the friction eases up. Run a good quality oil and change it and the filter after about 500 miles.

Senior Chief

Horsepower · Jun 30, 2008

Thanks all for the response.

BMC~ Great point. I was worried about a manual AND pusher because I didn't wanna reduce airflow at speed. I DEFINITELY don't want to lose my low "travel temp". Do you mount a pusher toward the top corner of the radiator closer to the exit point, or does it matter? I think I'll install a pusher fan, and look for the right manual fan. I'll also fabricate my shroud for a close fit to the fan, and to decrease cavitation.
Any ideas for the correct 7 blade fan without shopping the junkyards?

Thanks again, Erik.

Viperwolf1 · Jun 30, 2008

If it only affects it at idle, I would look to increase the fan and water pump speed at idle. Bump the idle speed up or find a smaller wp pulley.

oleguy74 · Jun 30, 2008

stock fan should be six blade.more than enough for stock to mild 302.check timming and belt tennision also.use a good 50-50 mix antifreeze.my 74 was bought in calif.stock ac.3-core rad no heat trbl until got stupid and put in a 351w.

Socal Tom · Jun 30, 2008

What fan are you running? I'd recommend a "race fan" from derale or one of the others, and make sure that the fan is 1/2 in and 1/2 out of the fan shroud.
What radiator are you running? Good aluminum radiators have 2 big cores instead of 4 small ones.
Tom

bmc69 · Jun 30, 2008

Horsepower said:
Thanks all for the response.

BMC~ Do you mount a pusher toward the top corner of the radiator closer to the exit point, or does it matter? I think I'll install a pusher fan, and look for the right manual fan. I'll also fabricate my shroud for a close fit to the fan, and to decrease cavitation.
Any ideas for the correct 7 blade fan without shopping the junkyards?

Thanks again, Erik.

The SPAL pusher is 12 or 14" and requires that you 'lose' yr hood latching assembly altogether and go with hood pins or the like. The SPAL is a potent fan (Ferrari uses them), draws a lot of amps and is pretty loud. Given akll that..I seriously doubt a 9" pusher fan tucked in the corner would do much.

broncnaz · Jun 30, 2008

I'm with Socal Tom. I think your main problem is that 4 row radiator most of the time the 4 rows have problems pulling enough air through them If your going to spend any money get a different radiator 3 row tripple pass would be your best bet.

justinoshea · Jun 30, 2008

bmc69 said:
The SPAL pusher is 12 or 14" and requires that you 'lose' yr hood latching assembly altogether and go with hood pins or the like .

Thats what I did, 14" (perma cool?). it spins as you roll down the road so it won't last forever even if its 'off', as the bearing will go at some point. still leaves room for a decent tranny cooler and a power steering cooler.

when I changed the stock fan out for a 19" flex fan & a steel shroud I noticed that the electric pusher now turns at idle, showing the increased flow.

To do it over I would go with the exploder acc. setup with a clutch fan.

Also, bigger tires will help. increases cool air flow under vehicle.;D

Horsepower · Jun 30, 2008

my mistake on the 4-core. it's the 2 core from Bronco Graveyard. Here's the detail.

Item #10609 - New
1966-77 Ford Bronco
See part description.
Proudly Made In The USA!

Solve all of your cooling problems with our new Extreme Duty Custom Aluminum Radiators!
These radiators are made to fit in the factory location with the stock type modified radiator mounts.
These radiators provide over 15% better cooling than the 4 core high efficiency copper/brass radiators!
With two 1" cores and 14 fins per. inch.
Better cooling is provided at low speed operating conditions, also the cores are brazed to the tank headers allowing the use of a 22-24lb. radiator cap and NO EPOXY!
The tanks are custom made from 3003 aluminum and can have additional brackets attached with R4043 welding rod.
This radiator does accept the stock fan shroud and clears all known conventional power steering conversions steering conversions.
The automatic transmission cooler fittings are larger than stock to allow race coolers to be attached.
NOTE:
This radiator needs adapters to hook up your stock trans cooler, it is made so you can choose your adapters to fit your OEM or aftermarket trans cooler. Adapters are readily available from local parts stores.
Includes 22-24 lb cap!
thanks, Erik.

Horsepower · Jun 30, 2008

Thanks again for all the great tips.
and JUSTIN~ Love the shed!!

72Sport · Jun 30, 2008

Horsepower said:
Hey Board~ My '74 gets to 250*+ at idle, but when driving it stays at 180*.
I was thinking about stripping out the manual fan/shroud and adding the largest electric Black Magic fan I could find. I figure I'd keep it on whenever driving the Bronc. Any thoughts on this?

Details-
-fresh 302
-Waterwetter
-180* Therm
-brand new alum 4-core radiator
-hi-flow WH water pump

Thanks, Erik

Stop the hot air from jumping over the top of the radiator and re-entering the top of the radiator on the front side. Try a little cardboard and and tape as a test. You just might be amazed. Block all necessary holes in the core support and on the sides of the radiator. I have ac and a couple of Derale fans mounted on the condenser. I have let it idle and removed the piece on the top of the radiator and watched the temperature shoot up. I then reinstalled it and watched the temp go back down. The removal of the top piece and re-installation was done with the engine at idle and the ac on after a 15 mile ride. The engine was not shut off and the hood was only open long enough to remove the piece above the radiator, about 30 seconds max. The fans do help but the biggest fix was the piece over the top of the radiator.

Heat at Idle

Horsepower

New Member

justinoshea

Sr. Member

bmc69

Bronco Guru

Master Chief

Bronco Guru

Horsepower

New Member

Viperwolf1

electron whisperer

oleguy74

Bronco Guru

Socal Tom

Bronco Guru

bmc69

Bronco Guru

broncnaz

Bronco Guru

justinoshea

Sr. Member

Horsepower

New Member

Horsepower

New Member

72Sport

Bronco Guru

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