4core vs. 3 core radiator - Team Camaro Tech
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post #1 of 13 (permalink) Old Jun 25th, 02, 08:08 PM Thread Starter
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I have a 68 small block car with a 3 core that is like new, however the motor runs a little warmer than I would like. Would a 4 core BB radiator make the difference. I have an 18" electric fan 2200 cfm 180 thermostat and a weiand 8208 pump which I thought was high volume. It should run cool. I am considering going back to the conventional fan and shroud and/or using a 4 core.
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post #2 of 13 (permalink) Old Jun 25th, 02, 08:42 PM
 
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did you check that 180 thermostat to be sure it opened at 180 or very close to 180??

i got a 160 degree once that would not open till almost 190....

put the thermostat in a pot a water with a fast reading thermometer keep an eye on it as water heats...(digital thermo's work great for this test BTW )

check that first IMO then check into other options...(also is it only running to warm when sitting at idle .or all the times after heat up??
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post #3 of 13 (permalink) Old Jun 26th, 02, 03:43 AM
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I think that electric fan may be your problem. I run a new 21" 2 core with a 400SBC,180* t-stat,stock fan and shroud with out problems. On a 90+ day in traffic,or slow cruise speed it does get around 190*-200* and no boil over.

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post #4 of 13 (permalink) Old Jun 26th, 02, 06:17 AM
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We do NOT have enough information to determine what is going on! Does it overheat at idle or cruising. Two differing problems requiring two differing solutions.

Idle overheating is usually due to lack of airflow if the engine cools cruising. A quality electric fan will ALWAYS PRODUCE MORE AIRFLOW AT IDLE AND SLOW SPEEDS than mechical fans! So, the jury is still out on that.

If it is overheating at cruising then it's likely that the carb is too lean or there is problems with air deflection at the radiator.

Check out my cooling forum at www.inccn.net/techforum.htm for more information.

ps....if you get a new radiator, make it a twin tubed 1" or more ALUMINUM radiator. They are equivalent to 5 row copper/brass radiators of equal size. No brainer.

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[This message has been edited by HOTRODSRJ (edited 06-26-2002).]
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post #5 of 13 (permalink) Old Jun 26th, 02, 06:49 AM Thread Starter
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temp is 190-200 at idle its not necessarily overheating but I remember it running cooler with the conventional fan and shroud, i would think that an 18" puller elec fan would do a good job at low engine speeds. thermostat is a delco 180 and should be working properly. there is no mech fan just the electric,but an additional fan won't be able to pull through the elec anyway. I have a 16lb cap, I'm considering an even higher lb as well.
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post #6 of 13 (permalink) Old Jun 26th, 02, 08:30 AM
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don't worry about it unless it starts to creep up hotter than that. remember, plain water at atmospheric pressure boils at 212 degrees, and if you add coolant and/or a higher pressure cap to the equation, it is pretty easy to get the boiling point up in the 230 range. where you are at is usually about optimum for power and durability, so don't sweat it.

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post #7 of 13 (permalink) Old Jun 27th, 02, 04:51 AM
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Railing68,
Pick up the September Surper Chevy if it's out and there is a short article on cooling systems. You are better off to run an aftermarket aluminum 2 core than a factory 3 or 4 core according to the article. The cores are at least twice as wide and dissipate the heat better than the stacked up thin cores the factory uses. At least according to them.

I know shrouding properly and a good high volume pump help keep the temps down. I have also had a lot of trouble with thermostats, even brand new Gates units I have had stick open and closed. I now drill a few bypass holes in any new thermostat before I install them. This allows me to limp it home or to a gas station if the thermostat fails closed a little water still bypasses. I will cause your warm up times to increase slightly, but it is worth it. Make sure the thermostat is working correctly first thing. Second thing I'd look at is that you have a puller fan behind the radiator, not a pusher in front of the radiator and that it is shrouded as best as it can be. Same goes if you run a mechanical fan, fixed or clutch type, shroud it and space the fan properly into the shroud and rrelatively close to the radiator. If you have a clutch fan make sure the clutch is working properly. Next I'd look at if the water pump isn't moving coolant quickly enough and consider a good high volume pump.
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post #8 of 13 (permalink) Old Jun 28th, 02, 02:31 PM Thread Starter
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I do have a bypass hole in the thermostat already, And I always run a delco because they seem to work right. The pump was supposed to be high vol. weiand 8208 and the fan is a puller 18' and seems to be pulling a lot of air. An aluinum radiator is a viable but expensive option.500$ the motor is in the break in period and could be a little lean but I don't think so. I need a good plug reading and some highway time. It still should run cooler than it is, around 180 even at idle. My coolant to water ratio is too high according to the previously attached links. But I have a hard time believing that 20% coolant 80% water will make a noticeable difference. But I will remove some fluid and add some distilled water. With the addition of the new pump and elec fan I thought it would run cooler not hotter than the stock pump and fan. On the previous motor prior to this rebuild.
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post #9 of 13 (permalink) Old Jun 28th, 02, 03:51 PM
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The SuperChevy article was not a good and accurate technical article as it was an advertisement for vendors and manufacturers.

But, nevertheless, the part about an aluminum radiator is correct.

The 18" part is good, but the real measure of work is wattage or continuous amperage. If it's only taking less than 20 amps, it's not the best fan for the application. There are better choices for your information.

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post #10 of 13 (permalink) Old Jun 28th, 02, 09:27 PM Thread Starter
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the fan pulls 19 amps and pulls 2200cfm, b4 I go out and spend the money on an aluminum radiator, I need to find out if the pump is high volume. What other fan options would you suggest. Like I said previously I am considering a fixed bladed 18" conventional with the stock shroud as an alternative to the elec. I saw alum radiators in jegs for My application they're 500$.
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post #11 of 13 (permalink) Old Jun 29th, 02, 01:38 AM
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Put the biggest, fattest fixed mechanical fan on that you can find, and shroud it.

This is the cheapest route. Then you can go up from there. By the way, after I installed a 4 core radiator in mine, I still had cooling issues--it's just took a lot longer to heat up, but it still heated up too much for me at idle in 90+ heat.

So I got a big, fat, heavy pitched fan out of junkyard and cleaned it up and installed it. Problem solved. I was running a flex fan. To test it, I parked my car in the garage (zero airflow/wind) when it was 90* out and let it run for 22 minutes. She got just below 190*.

Give a try.

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post #12 of 13 (permalink) Old Jun 30th, 02, 02:28 AM
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The temperature range that you are worried about is NOT an issue with your engine. If it worries you then it's your money. As long as temperature will stabilize, a 230 degree reading does not bother me. Any more tho? On top of that, new engines will run hotter for awhile, so the increase in temperature compared to old does not surprise or concern me.

However onward!

It sounds like the fan is enough according to your description. I could not ascertain this completely, but if you changed the thermostat also, if so the operating range can differ slightly. Also, thermostats with relief holes drilled in them can offer slightly differing temperature readings due to outside ambient temperatures as well. Some of this could be what you are experiencing.

Your mixture of antifreeze will not affect the cooling ability at idle when the issue is airflow. You have to have air to remove any additional heat the coolant will bring to the radiator. If you are holding coolant, a higher cap will not help either unless you are worried about going up further in a run away heating situation, then they are good insurance policies. A typical 10 psi buildup in a cooling system will provide boiling protection to 239 degrees F.

Actually the system sounds pretty solid. The only easy, but expensive upgrade is one of two methods. A new radiator from PRC, go to www.streetrodstuff.com/Product/157 for a custom made radiator for under $300! Great quality too. Contact [email protected] and no I am not a commission saleman!

You could step up with twin Spal fans that will set you back a couple of hundred as well.....or both upgrades.

The mechanical fan can be put back on, but cluched fans have a checkered past with consistent performance, and fixed units eat up to 45hp....yes, I said 45hp, according to tests I have done and corroborated at

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post #13 of 13 (permalink) Old Jun 30th, 02, 03:20 AM
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Railings,
Here are the GM part numbers for a 69 SB car with A/C if you want to go mechanical. I just put them on my car because someone had installed a cheap flex fan and I didn't want it coming through the hood! It works great.

Fan # is 00393996 (18" diameter with 7 blades) this is a genuine GM replacement not original looking - the blades have more pitch than the original one did.

Fan clutch # is 12306569 or A/C Delco # 15-4218

I stay away from aftermarket fan clutches, I've had bad luck with them most of the time. Pay a little extra and get something that works well.

Forgot to add cost: fan $82.00 , fan clutch $55.00

Good Luck

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[This message has been edited by drew69 (edited 06-30-2002).]
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