1971 302 - can't get it to run cool

[Perpendicular]

Newbie on the forum - looked and am not seeing any prior threads discussion this so forgive me if it has been covered before. I see people talking about front runner systems doing different fans, etc. No one is talking stock type radiator with standard v-belt pulleys so thought i would post this here.

1971
302
3 speed on the column
Bigger wheels and tires
V-belt configuration

Installed a vintage air system. I then put in a 3000cfm puller fan and an aluminum 3 row radiator. I also put in a small pusher fan (had to be small due to the hood latch).

Made an aluminum fan shroud just for this setup.

Installed a new 180 t-stat. Verified it is opening as expected by the gauge.
Installed a high flow water pump.

As of right now I cannot get this thing to run below 225-230 when running higher RPMs around the neighborhood. Before I did the water pump it would hit 240 doing 60 MPH or so.

Anyone have any experience with getting this setup cool?
Do they make a different water pump pully setup to get it moving better?

What am I missing?

When I run a temp gauge the t-stat housing is about 221.

I am at a loss and hoping someone has some ideas I can check out.

 

[ared77]

"Installed a high flow water pump."

Sometimes I believe I've heard others say that high flow can actually contribute to the problem. The thinking is that coolant flows through the radiator so fast there isn't adequate time for it to be cooled. But I'm no expert!

Others on here will chime in with better answers soon!

Welcome to the best Bronco site!

Norm

 

[rocknhorse76]

Best cooling setup you’ll find is the Explorer serpentine with the clutch fan. That “3000 CFM” puller fan you have can’t even come close to moving the amount of air the Explorer fan pulls!

 

[Broncobowsher]

Post pictures. Many of us can just look at what you have and know what works and what doesn't.

Shroud is generally good, electric fan is generally bad. Most aftermarket fans, especially ones that advertise high CFM ratings) are junk and can't actually move enough air through the core. Fine when in free air, but when forced to actually work, fight the restriction of the fins in the radiator, falls shy of being functional.

The high flow moving water too fast to cool in the radiator, if that were true it would also be moving too fast to take in heat out of the block. Why don't they use it from the factory, because the extra drag eats fuel economy. But I will leave the quality of the pump up to suspect.

Engine tune up? How was the timing set? Use a timing light? Set by ear? Set by vacuum gauge? What do you have the base timing set to?

 

[SteveL]

"Installed a high flow water pump."

Sometimes I believe I've heard others say that high flow can actually contribute to the problem. The thinking is that coolant flows through the radiator so fast there isn't adequate time for it to be cooled. But I'm no expert!

Others on here will chime in with better answers soon!

Welcome to the best Bronco site!

Norm

I ran into this on another vehicle. Put a stock pump back on and everything was fine.

 

[Perpendicular]

Let me grab some pics and I will post them.

The water pump - did reduce by at least 5 degrees, that I have proven. It was hotter temps yesterday than when I tested with the stock pump.

Fan - what would the best blade setup be if I were to go back? Remember, there is so little room with the compressor, etc., to do anything crazy.

Thanks for the help!

 

[okie4570]

Let me grab some pics and I will post them.

The water pump - did reduce by at least 5 degrees, that I have proven. It was hotter temps yesterday than when I tested with the stock pump.

Fan - what would the best blade setup be if I were to go back? Remember, there is so little room with the compressor, etc., to do anything crazy.

Thanks for the help!

7 blade fan will do wonders over a 5 blade if that's what you're running.

 

[Perpendicular]

7 blade fan will do wonders over a 5 blade if that's what you're running.

I am running electric but with the above comments I am wondering what fan would be best utilizing the stock shroud? I don't want flex, it was a stock fan before but they are bent so not usable.

 

[Slowleak]

Okie is right…..Get a cheap anemometer from Amazon and check your airflow thru the grill at idle. I tested several different fan blades years ago and the stock 7 blade Ford flex beat them all. I have a stock Bronco with dealer A/C. It can be a tight fit but it’s worth it. I switched to a slightly smaller fan pulley for more fan speed but I don’t think it is necessary.

I’m pulling 72% more air thru the radiator now:
Six blade 17 in. stock fan, stock pulley - 492 ft/min
Seven blade 18 in. stock flex fan, 5.4in pulley - 846 ft/min

 

[Perpendicular]

Okie is right…..Get a cheap anemometer from Amazon and check your airflow thru the grill at idle. I tested several different fan blades years ago and the stock 7 blade Ford flex beat them all. I have a stock Bronco with dealer A/C. It can be a tight fit but it’s worth it. I switched to a slightly smaller fan pulley for more fan speed but I don’t think it is necessary.

I’m pulling 72% more air thru the radiator now:
Six blade 17 in. stock fan, stock pulley - 492 ft/min
Seven blade 18 in. stock flex fan, 5.4in pulley - 846 ft/min

Are you using the stock shroud with the seven blade? Which fan if I can ask? I haven't had the best luck on getting the correct thing first try :/

I like those numbers!

 

[Slowleak]

Are you using the stock shroud with the seven blade? Which fan if I can ask? I haven't had the best luck on getting the correct thing first try :/

I like those numbers!

It’s a stock shroud with a Ford fan Part# CF-D4TA-8600-HA I have a 5.4 inch pulley from CVR Racing but I don’t think you need it.

 

[tasker]

put a Motorcraft 192 thermostat in it (RT-1139) bet it fixes your problem

 

[Brush Hog]

Mine ran around 220 degrees around town. Would go up to 240 stopped/idling. Advanced timing to about 12 degrees btdc and richened up the carb adjustments. Dropped temps by 30 degrees. Never goes past 190 even when it’s 100+ outside. Running a Tom’s stock replacement aluminum radiator and a 7 blade clutch fan.

 

[Perpendicular]

Thanks all. Working through your suggestions.

 

[Perpendicular]

Interesting trivia piece - the stock Bronco fan blades (5 blade) have less of a pitch than the Mustang fan blades (also 5 blade).

Figured I would share that for those that need research later on.

 

[Yeller]

Timing is always my first question. Is the vacuum advance working? Does it curve up and increase with RPM? All things that get assumed are good. Seen a lot of base line timing set correctly, but vacuum advance not working and or frozen curve plates inside the distributor and over heating is the result.

Radiator is second. Is it an old stock unit or something new? Seen a lot of old radiators that didn’t leak, looked good, even flowed well that just weren’t up to the task anymore. The tubes were thin enough to collapse with temp and pressure.

Second the anometer test. I’m always skeptical of electric fans when they are not from an OEM application.

 

[gr8scott]

the stock Bronco fan blades (5 blade)

Wasn't the stock Bronco fan 7 blade?

7 Blade Radiator Fan, SBF V8, 66-77 Ford Bronco

NEW OE-Style Radiator Fan for 66-77 Classic Ford Broncos. Fits 289, 302 & 351W V8 Engines. 7-Blades, 18 inch Diameter. This fan is made exclusively for TOMS OFFROAD and is a direct replacement of the factory original radiator fan. Just like the original with the exception it does not have any of...

tomsoffroad.com

 

[m_m70]

Timing is always my first question. Is the vacuum advance working? Does it curve up and increase with RPM? All things that get assumed are good. Seen a lot of base line timing set correctly, but vacuum advance not working and or frozen curve plates inside the distributor and over heating is the result.

I always start here and it usually fixes the cooling issues I come across. Best part is that checking these things are free, adjusting these things are free and if you have to fix these issues it's a whole lot cheaper than throwing a ton of money at electric fans, oversized radiators, high-flow pumps etc...........

Assuming your 302 is stock so should not run hot with the stock cooling system and properly tuned motor.

Interesting trivia piece - the stock Bronco fan blades (5 blade) have less of a pitch than the Mustang fan blades (also 5 blade).

Completely different "animal". Engine compartment, air flow etc....

 

[spap]

Did it run hot before you installed the ac, ?

 

[bmc69]

Okie is right…..Get a cheap anemometer from Amazon and check your airflow thru the grill at idle. I tested several different fan blades years ago and the stock 7 blade Ford flex beat them all.

A 7-blade fixed-pitch fan on a MD clutch (460 Camper Special HD cooling setup), in proper fitted shroud, is the best cooling combination I've ever found. I'm not surprised the 7-blade flex fan had good numbers too.