The Best Possible Radiator

[1972RedNeck]

I would like to upgrade the radiator in my '72 K2500. Mine keeps it cool just fine but in city traffic it gets warm. I have a flex fan on it.

My truck currently has a stock 4 core in it. I would like one that fits in my mounts. It needs to be tough, as the gravel roads I drive on are rough.

Is aluminum as sturdy as brass and copper? One thing I would prefer NOT to have is the very fine high efficiency radiator.

All input AND, believe it or not, opinions are appreciated.

[C20-67_N_MO]

When I had my '72 truck I bought a nice aluminum raditor from these guys.

http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

[1972RedNeck]

Will those fit in my mounts or will I need 3 core ones?

[Clyde65]

I would ditch the flex fan first. use the stocker and a shroud and you should be good. if it still is warm, put an electric pusher in front of the condensor.

[1972RedNeck]

I have a shroud. The fan is inside the shroud about like the original. Would a clutch fan be better?

[hayhauler71]

Put a 5 or 7 blade clutch fan on and call it done

[1972RedNeck]

Originally Posted by hayhauler71

Put a 5 or 7 blade clutch fan on and call it done

I assume 7 blades are better than 5? I will get one of those.

That still brings me back to my original question: What is the best radiator that I can get?

[C20-67_N_MO]

Originally Posted by 1972RedNeck

Will those fit in my mounts or will I need 3 core ones?

Yes those would fit.

[bigguy69]

They look good
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[ubtripn]

With the clutch fan you may not need a new radiator. That is the amount of efficiency difference between worthless flex-blades and clutch fans. Just my own opinion after doing battle with a new flex fan. I replaced everything to new, radiator from Napa, Water-Pump, Thermostat and Flex Fan and it would NOT cool. After I finally narrowed it down to the flex fan with the help of the forum it runs perfectly. 180 in 95 degree heat and that is without a shroud, stopped in traffic with lava flowing beneath me. Well, hot asphalt anyway.

[C20-67_N_MO]

ubtripn: So what you're saying is you replaced the flex fan with the clutch fan setup and it now cool much better now, right?

[ubtripn]

Absolutely. 1000 percent difference. The flex fans don't produce flow, to be honest I don't even know why they exist, maybe for drag racing or something. I put a cig burning in front of my rad with it on and the smoke went the OTHER way! The clutch fans come in two types, centrifigal or thermal. Both work well but have to be close to the rad so you need the right spacer. Around an inch or even 7/8's away from the rad works well that way a bump or won't make it hit the rad and the thermal ones are triggered by heat hence the need for closeness.

You bolt the spacer and fan to the pulley to the water pump just the same but they are free spinning with the engine off. At idle they spin faster than the pump is rotating providing more air while stopped and at full throttle they spin less I think giving you more horse power but most importantly, the pitch is correct. The air flows HARD. They look like a flex fan but with a disk on the front. The centrifgal kind have fluid that expands causing it to spin faster than the pump and the thermal kind have coils or something that respond to the heat applying pressure to the fan causing it to spin faster as well.

Anyway, I could be off on the little details but the point is that the centrifigal clutch was the key for me AFTER I replaced every other component. I could have started with just that. I would start there. If you add a shroud it's 50% better.

[Stocker]

You have a 4-core radiator, but you don't say it is bad.... so why replace it? A good 4-core will give you all the cooling you need, as long as the rest of your cooling system is in order. You already have a shroud. You're running 50% antifreeze and have a good t-stat (180# to 195#), right? Toss the flex fan and get a 7-blade clutch fan, and you should be good to go.

[ubtripn]

He's right, this is where the forum saved me.

[Stocker]

Originally Posted by ubtripn

I put a cig burning in front of my rad with it on and the smoke went the OTHER way!

Ah, but that's because that fan was designed to turn in the opposite direction...

Originally Posted by ubtripn

The clutch fans come in two types, centrifigal or thermal. Both work well but have to be close to the rad so you need the right spacer. Around an inch or even 7/8's away from the rad works well that way a bump or won't make it hit the rad and the thermal ones are triggered by heat hence the need for closeness.

With a shroud, the fan should be centered in the shroud opening.... which on my OEM K20 is several inches from the radiator, and no spacer is used.

[into69z]

I have a fresh engine (4000miles) new 4 row radiator, new clutch fan, water pump,shroud-all exactly like the factory made it and I have no over-heating problems. I do have a problem with A/C when i stop in traffic-the system needs an electric fan for those times. If I had it all to do over again, I would go with a new aluminum set-up from entropyrad.com. It is a direct bolt-in and has a custom shroud with two 11" electric fans that pull 3000cfm's each-it good enough for 800 hp or so. I watched the 48 hour Camaro build and this is the radiator they used for that project, then I saw the car in action in Nashville racing the solaum course with the a/c on, with the temperature over 105 degrees-they said it never got over 180 degrees! I think this is the best set-up for a great cooling system. You need a system as stated before , all the correct pieces, whether stock or custom-not just a great radiator.

[1972RedNeck]

Can I get a fan with clutch fan type blades, but without the clutch? I like a fan engaged at all times. It makes it easier to lose body parts.

My second choice would be a clutch fan with an electric clutch (like semi's).

[into69z]

It needs to be tough, as the gravel roads I drive on are rough.

forgot to add that speedwaymotors.com has two different types of screens that are used for dirt track cars to keep the rocks and dirt out of the radiator fins........reminds me of the ones Chevy used to sell in the parts department.

[Stocker]

Originally Posted by 1972RedNeck

Can I get a fan with clutch fan type blades, but without the clutch?

I would never recommend doing that. The blades pull so much air, the roar would drive you crazy... not to mention the amount of power it would take to keep it churning full time.

I can't think of any valid reason not to use a clutch fan, unless you simply prefer to go electric. I've had 'em on quite a few vehicles over 40+ years with no issues. My K20 still has the original clutch fan (though I did have to add a bit of fluid once, many years ago).

[1972RedNeck]

It might be a bit spendy but I think this would be the way to go.

http://www.summitracing.com/parts/RNB-622-001/

[stroked69]

be-cool offers a bolt in system for your truck. Includes alum radiator, twin fans, harness, mounting brackets. I bought one for my 69. It bolted right up.

[mcmlxix]

These guys are supporters on the Chevelle borad I'm on.... Haven't used one but they get nothing but compliments on thier products

http://www.chevellecooling.com/64.html

[1972RedNeck]

Originally Posted by mcmlxix

These guys are supporters on the Chevelle borad I'm on.... Haven't used one but they get nothing but compliments on thier products

http://www.chevellecooling.com/64.html

What would I have to do to get a 19 inch tall one to fit?

[mrein3]

I too had issues with keeping my engine cool in stop and go traffic. When I bought the truck the PO had installed a 4-blade fan WITHOUT a clutch. I had a 7-blade fan and clutch in my shop - probably off of an a-body as that is the only other Chevrolets I've ever owned. It was the right diameter and was centered perfectly in the shroud. No more cooling issues.

What I would if I was you is:
#1 Ditch the flex fan. As soon as longhornman sees this post he'll post a picture of a hunk of a flex fan blade sticking through the hood of a truck. People have died when those things came apart with the hood open. When I bought my 1971 convertible it had a flex fan on it. That flex fan was on the shop floor within 30 minutes of getting it home. Replace it with a stock 7 blade and stock replacement clutch and don't look back.

#2 Roll around with the 7 blade and clutch for a while and see how things work out.

If your stock fan is centered in the shroud opening and your radiator has decent water flow inside of it you'll be just fine.

[1972RedNeck]

Originally Posted by Stocker

I would never recommend doing that. The blades pull so much air, the roar would drive you crazy... not to mention the amount of power it would take to keep it churning full time.

I doubt I would mind it too much. How much horsepower would I lose?

From what I have read, clutch fans don't go as fast as the water pump because the liquid just makes it spin faster?

Is there such a thing as a fan with clutch fan-type blades and no clutch?