68 RR 383 Still Getting Hot

[dburnett6263]

I had the rubber flaps over almost every available space that wasn't the fan. It may just be my car, I've read many that work, but not in my heat. The explanation I was given was that the flat shroud causes a high pressure zone, keeping air from coming in at highway speeds even w the flaps. A louvered hood, raise rear of hood etc than help creat a low pressure zone would help suck air through at highway speeds. But for my car weren't an option.

Yes, I've thought as well, is there some way to get some heat out from under the hood, I do not want to do any cutting and hacking.

 

[diesel_lv]

Yes, I've thought as well, is there some way to get some heat out from under the hood, I do not want to do any cutting and hacking.

Other than cutting, no. But w my setup, mechanical fan n factory shroud, it's not an issue. I tried 2 different 12" dual fan setups, non worked at speed. All did well in stop n go w a/c on. And w factory shroud, stays cool at highway speeds. So this means that everything is sized correctly, but that at highway speeds there was a restriction. If you look down your carburetor, you see the barrels narrow in the middle, a venturi which causes a low pressure zone helping increase velocity of air. It is smooth and curved. A factory shroud is smooth and gradually comes back to a narrow area, causing a low pressure area. The metal shrouds on electric fans are flat n generally, not always, cause a high pressure zone. If you look at most factory electric fans, they are in a plastic molded shroud that gently curves also.

 

[pnora]

To the best of my knowledge the pump housing is original to the engine. I have 2 electronic gauges, 1 being the Dakota Digital, the other the Terminator readout. Checking at idle with my laser unit, everybody's pretty close. Thanks. Dale

With the iron housing you should be fine. It was the aftermarket aluminum at one time had a known restriction. Did you always have a condenser in front of the radiator?

 

[diesel_lv]

Here's some temp references for you on my 496 in 120° day. 1st 2 are in town stop n go after long highway drive, digital temp then what gauge shows. 3 n 4 are during long highwaydrive at 70mph, 5 n 6 are after idling 10 minutes after all the above w a/c on.

 

[dburnett6263]

With the iron housing you should be fine. It was the aftermarket aluminum at one time had a known restriction. Did you always have a condenser in front of the radiator?

No. AC was not on the car when I got it, added during the restore. Thanks. Dale

 

[dburnett6263]

Here's some temp references for you on my 496 in 120° day. 1st 2 are in town stop n go after long highway drive, digital temp then what gauge shows. 3 n 4 are during long highwaydrive at 70mph, 5 n 6 are after idling 10 minutes after all the above w a/c on.View attachment 1150829View attachment 1150830View attachment 1150831View attachment 1150832View attachment 1150833View attachment 1150834

I could live with those conditions. I don't get a lot of change from down the road, 50ish MPH (200-210), so when I drop into stop and go it goes up from there (220+ pretty quick) and that's no AC. I don't have anything exotic that would suggest a cooling issue and feel I have plenty of radiator. Just can't get enough air flow through it. After talking with you and input from others I'm thinking the shroud itself (in my case) may be the biggest issue. I would like to see some mechanical fan CFM data at some given conditions. It's probably out there I haven't found it yet. Thanks. Dale

 

[diesel_lv]

I could live with those conditions. I don't get a lot of change from down the road, 50ish MPH (200-210), so when I drop into stop and go it goes up from there (220+ pretty quick) and that's no AC. I don't have anything exotic that would suggest a cooling issue and feel I have plenty of radiator. Just can't get enough air flow through it. After talking with you and input from others I'm thinking the shroud itself (in my case) may be the biggest issue. I would like to see some mechanical fan CFM data at some given conditions. It's probably out there I haven't found it yet. Thanks. Dale

I've researched everywhere, no data I could find. But cfm is is irrelevant at highway speeds. Area of radiator and area that air has to flow thru matter. At an idle, some electric fans can cool better than a mechanical. 2k+ rpm as apposed to 900 rpm. My bone stock '67 Coronet came factory a/c n automatic w 383. My great grandmother bought it brand new. I rode in it every summer as a kid and inherited it. It came w 26" radiator, 7 blade fan, fan shroud and fan clutch and 180° t-stat. The a/c would always freeze you out and it "Never" overheated. In west TX desert heat, Las Vegas heat, and my heat here.

Something that hasn't been brought up, I believe (could be mistaken) there was a different water pump for a/c cars. Also check that the water pump pulley is the correct size.

 

[#41]

A mechanical fan is limited by motor rpm's so it produces the least cfm at idle where it's needed most (no natural airflow) whereas a 3,000 cfm electric fan delivers it regardless.

The mechanical clutch fan is specifically designed to work BEST at idle. The entire idea of a mechanical fan with a clutch is to mostly disable the fan above idle because the fan is not needed anymore. You need zero fan cfm once you are moving so it's no advantage to continue to run your fan whether its mechanical or electric.

One of the weaknesses of typical electric fan systems is that even though the fans may flow lots of cfm, they don't draw the air draw through the radiator as efficiently. This is because they are mounted closer to the radiator and have less tendency to draw as evenly across the entire radiator face, even with a shroud. Also, consider the math for the area of a circle: One typical sized 18" mechanical fan = 254 square inches of fan blade area. That is more than the equivalent area of TWO 12" electric fans.

I am not saying electric fans suck.... they are light and don't leach off horsepower, but they are not necessarily the end-all answer to cooling problems. You can accomplish a lot, or even more with a simple belt-driven fan and shroud.

 

[dburnett6263]

I've researched everywhere, no data I could find. But cfm is is irrelevant at highway speeds. Area of radiator and area that air has to flow thru matter. At an idle, some electric fans can cool better than a mechanical. 2k+ rpm as apposed to 900 rpm. My bone stock '67 Coronet came factory a/c n automatic w 383. My great grandmother bought it brand new. I rode in it every summer as a kid and inherited it. It came w 26" radiator, 7 blade fan, fan shroud and fan clutch and 180° t-stat. The a/c would always freeze you out and it "Never" overheated. In west TX desert heat, Las Vegas heat, and my heat here.

Something that hasn't been brought up, I believe (could be mistaken) there was a different water pump for a/c cars. Also check that the water pump pulley is the correct size.

I will check that, pulley is the original, non AC car. So far I'm not running the AC till I get this ironed out. Thanks

 

[pnora]

That's a custom valance / cowling I had made to compliment the engine compartment clean up. I did take it off and drove around for a couple days, no noticeable difference. I really scratch my head when I read your statement and talk to folks cooling more iron than I am with similar or even lesser systems that have no issues at all. I just haven't found my sweet spot yet. Yes, ColdCase does list them but pic is rad only, no fans, I didn't search any further than that. Thanks for your input. Dale

Have you tried running with the custom shroud off with the cold case set up. I was doing some work on mine and it ran about 180 with the a/c on. I ran it over an hour in the shop. I was afraid that the 528 Hemi would be a problem to cool and I just can not believe how cool it runs. It was 80 degrees Sunday when I was running it.

 

[dburnett6263]

Have you tried running with the custom shroud off with the cold case set up. I was doing some work on mine and it ran about 180 with the a/c on. I ran it over an hour in the shop. I was afraid that the 528 Hemi would be a problem to cool and I just can not believe how cool it runs. It was 80 degrees Sunday when I was running it.

Yes, I have tried it without the new custom shroud / valance / cowling, no change. I've been dealing with this issue before the change to the larger ColdCase setup. It's a nice system.

 

[dburnett6263]

The mechanical clutch fan is specifically designed to work BEST at idle. The entire idea of a mechanical fan with a clutch is to mostly disable the fan above idle because the fan is not needed anymore. You need zero fan cfm once you are moving so it's no advantage to continue to run your fan whether its mechanical or electric.

One of the weaknesses of typical electric fan systems is that even though the fans may flow lots of cfm, they don't draw the air draw through the radiator as efficiently. This is because they are mounted closer to the radiator and have less tendency to draw as evenly across the entire radiator face, even with a shroud. Also, consider the math for the area of a circle: One typical sized 18" mechanical fan = 254 square inches of fan blade area. That is more than the equivalent area of TWO 12" electric fans.

I am not saying electric fans suck.... they are light and don't leach off horsepower, but they are not necessarily the end-all answer to cooling problems. You can accomplish a lot, or even more with a simple belt-driven fan and shroud.

I'm with you! I like the coldcase setup but in my case just can't seem to get the right airflow going.

 

[pnora]

Yes, I have tried it without the new custom shroud / valance / cowling, no change. I've been dealing with this issue before the change to the larger ColdCase setup. It's a nice system.

With not seeing changes it almost comes down to flow, or restriction. Pump or pump speed. Hose is not collapsing?

 

[Ccas]

This topic has been out there a long time and my problem is similar to many others, how hot is too hot? Many different thoughts on this and I realize different conditions can have an effect. I personally am a 200 max guy. Over the last few years have been through various 22" radiator, shroud, and fan (electric & mechanical) combo's with basically the same results, too hot, 205 down the road, 220+ at idle. Can't even think about running the AC. This is a typical August day in Southwest Ohio, upper 80's with close to 70deg. dewpoint. I've checked this with my hand held temp gun, pretty close. Engine is original 383, .040 over, head and valve train work, comp cam (.230/.236 @ .050), AR stainless headers. 6AL box, MSD billet dizzy (no vac. adv.), Holley Terminator Stealth EFI, Tremec TKO 5 spd. Timing 14deg. @ 950 idle, AFR 13.7.
During the pandemic went through some upgrades and mods which included the Tremec, Terminator, Dakota Digital, cleaned up the engine compartment. Along with this I went with a Cold Case MOP754K 26in. 2 rows of 1.250in. tubes, 16 fin/in. and dual 12in. fan kit claiming 3200CFM. Reviews on this unit are mixed from greatest thing since sliced bread to great radiator but ditch the fans. Can no longer find it as a kit on the cold case website, maybe that's a clue. Anyway, thinking on ditching the fans and going back to what Mother Mopar intended, that being factory shroud, 7 blade fan w/thermal clutch. I have 4in. of space so should be plenty of room. Before I move forward with anything I'm open to input, comments, advice. BTW have a couple of nice 22in aluminum's come get them! 3 pics. Thanks Dale.

View attachment 1150206 View attachment 1150207 View attachment 1150208

First of all, that engine bay if fantastic. Wow. Well done!

Did I miss it or do you not have the results of the new Cold Case combination. It should be significantly better than the old 22" unit regardless of whether you run the dual electric fans or a mechanical fan and clutch.

 

[dburnett6263]

First of all, that engine bay if fantastic. Wow. Well done!

Did I miss it or do you not have the results of the new Cold Case combination. It should be significantly better than the old 22" unit regardless of whether you run the dual electric fans or a mechanical fan and clutch.

First, thanks for the complement!
I copied some of this from my original post.
I personally am a 200 max guy. Over the last few years have been through various 22" radiator, shroud, and fan (electric & mechanical) combo's with basically the same results, too hot, 205 (min.) down the road, 220+ at idle and climbing. Can't even think about running the AC. This is a typical August day in Southwest Ohio, upper 80's with close to 70deg. dewpoint. I've checked this with my hand held temp gun, pretty close. Engine is original 383, .040 over, head and valve train work, comp cam (.230/.236 @ .050), AR stainless headers. 6AL box, MSD billet dizzy (no vac. adv.), Holley Terminator Stealth EFI, Tremec TKO 5 spd. Timing 14deg. @ 950 idle, AFR 13.7. Only ColdCase data I've seen is what's on Summit's site. This is a nice clean setup and install. Others have these cooling more iron than I do with no problems and running at lower temps. I'm still searching for what's different about my setup. Temps. are still what is shown above. Maybe I shouldn't be alarmed as its at least not pucking now but not in my comfort zone. Any thoughts or suggestions are welcomed. Thanks. Dale

 

[diesel_lv]

Finally found the name of the company I used for the radiator, which works great, and the e-fan/shroud combo, which didn't work. It's Entropy Radiator. Looks to be about the same spec as the ColdCase.

 

[pnora]

Are both fans operating in the right direction? Just thinking out of the box. If by some chance one was made wrong and pushing instead of pulling? What temp do the fans come on at? What is controlling the fans?

 

[dburnett6263]

With not seeing changes it almost comes down to flow, or restriction. Pump or pump speed. Hose is not collapsing?

Hose isn't collapsing, with cap off looks to be decent flow as compared to what I've seen in other vehicles.

 

[dburnett6263]

Finally found the name of the company I used for the radiator, which works great, and the e-fan/shroud combo, which didn't work. It's Entropy Radiator. Looks to be about the same spec as the ColdCase.

That looks exactly like the 22" setup I got from ECP (Engineered Cooling Products) 2-1" tubes and same monster fans that pulled about 50 amps and very noisy! That setup was about 200 down the road but shot up pretty quick at idle. Still out of my comfort zone with AC.

 

[dburnett6263]

Are both fans operating in the right direction? Just thinking out of the box. If by some chance one was made wrong and pushing instead of pulling? What temp do the fans come on at? What is controlling the fans?

Yes, they are both pulling. They are controlled from the Terminator EFI, #1 on 170 off 160, #2 on 175 off 165. Have them set there to get them going fairly quick, They are consistent. Thanks.