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Idle temp airflow or tuneup? #2678873
07/18/19 09:47 PM
07/18/19 09:47 PM
Joined: Aug 2009
Posts: 36
Springfield VA
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GTXOnsfri Offline OP
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GTXOnsfri  Offline OP
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Joined: Aug 2009
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Springfield VA
While I love this car, the engine temp at idle has been an issue for years. I thought it would go away when we rebuilt the engine but nope. I’m about to have the floor pans replaced and I though about changing the yoke to fit the 26” radiator at the same time but I thought I would try one last time to see if there is something I’m missing.

The issue is the same as always, when the car is moving it runs at 181 degrees. As soon as you stop and idle the temp starts heading up. If I’m stuck in traffic on the highway the temp can reach 230 and I’m already running the heater at full, putting the car in neutral when I can. I suspect it would keep climbing if I let it. I have the air dam on it. I’ve gone as far as trying to gauge the airflow with a meter. I added an electric 16” pusher fan and that did squat except sound like crap. I’ve tried clutch and no clutch.

So is it lack of airflow or am I missing something. A 440 with no ac and auto gets the 22” radiator. I’d hate move up to the 26 and still have the problem. Advice?

Details:
440 (.030), Stealth Aluminum Cylinder Head, Comp Cam Adjustable rockers (1-5), Edlebrock CamShaft 2192. MSD Digital 6A, 180 Thermostat, Edelbrock 8814 BB Mopar High Volume Aluminum water pump.
727 Auto trans (Bob Cope Racing), 3.23 gears
Atomic EFI: Air/Fuel targets [Idle 13.9, Cruise 14.0, WOT 12.8, Boost 11.5]; Ignition timing [Idle 800, total RPM 2500, Idle advance 17.0, Total advance 34.0, Vacuum Advance 10.0]
22 Inch Aluminum Radiator (US Radiator), with shroud and stock fan with clutch. 50/50 antifreeze. The fan is about halfway into the shroud.

IMG_20190611_184329.jpgIMG_20190705_200652.jpgIMG_20190705_200705.jpg
Re: Idle temp airflow or tuneup? [Re: GTXOnsfri] #2678891
07/18/19 10:11 PM
07/18/19 10:11 PM
Joined: Jan 2003
Posts: 1,600
s. e. pa.
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calrobb2000 Offline
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calrobb2000  Offline
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s. e. pa.

hi
looks like you have the 5 blade clutch fan ?

have you tried the 7 blade clutch fan ?

do you have the correct pulleys to move the water at the correct flow rate at idle ?

Re: Idle temp airflow or tuneup? [Re: calrobb2000] #2678899
07/18/19 10:26 PM
07/18/19 10:26 PM
Joined: Aug 2009
Posts: 36
Springfield VA
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GTXOnsfri Offline OP
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GTXOnsfri  Offline OP
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Springfield VA
Thanks, yes, I have tried the 7 bladed fan, and a flex fan. I didn't see a difference, it still rockets up when you stop. I also tried to use a smaller pully on the water pump to overdrive the pump and fan but the pully touched the mounting bolts. As most of us, I have a collection of part stacking up. Hell, that's the third radiator. When I bought it 7 years ago it had a C-body radiator, I swapped that the correct B-body 22" I bought off e-bay for a couple hundred and spend another couple hundred re-coring that and using the metal two-part shroud. Then I spent even more on the aluminum 22" radiator. So another $600 or $700 in a 26" radiator is hard to swallow. At this rate I will have enough spare parts to finish off a rolling body.

Re: Idle temp airflow or tuneup? [Re: GTXOnsfri] #2678902
07/18/19 10:41 PM
07/18/19 10:41 PM
Joined: Mar 2011
Posts: 1,198
Michigan
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Transman Offline
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Transman  Offline
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Posts: 1,198
Michigan
So the answer is no - you haven’t installed a larger crank pulley or smaller water pump pulley.

Try the seven blade fan with over driven water pump.

Make sure the timing is correct. That means start with checking the damper against true TDC.

Pretty car by the way.

Last edited by Transman; 07/18/19 10:44 PM.
Re: Idle temp airflow or tuneup? [Re: GTXOnsfri] #2678905
07/18/19 10:47 PM
07/18/19 10:47 PM
Joined: Jan 2003
Posts: 1,600
s. e. pa.
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calrobb2000 Offline
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calrobb2000  Offline
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Joined: Jan 2003
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hi

what dia is lower pulley , i think mine is app 7 in . there is a 5 in one also from small block i think .

mine can sit in traffic and never reach half way ?

what side is the lower rad exit on ?should be opoisit top entrance .

have you tried the factory flex fan , they move lot of air at low speed ? after mkt fans are worthless !

Re: Idle temp airflow or tuneup? [Re: calrobb2000] #2678906
07/18/19 11:14 PM
07/18/19 11:14 PM
Joined: Aug 2009
Posts: 36
Springfield VA
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GTXOnsfri Offline OP
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GTXOnsfri  Offline OP
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Springfield VA
I think the water pump pully is 6 3/4 and the lower pully is 6 3/8. I tried a 6 1/2 water pump pully and you can see how it was scraping the water pump bolts. There probably less than a 1/4" between the pullies, so I didn't try a larger lower pully.

IMG_20190718_225729.jpgIMG_20190718_230000.jpgIMG_20190718_230019.jpg
Re: Idle temp airflow or tuneup? [Re: calrobb2000] #2678908
07/18/19 11:20 PM
07/18/19 11:20 PM
Joined: Aug 2009
Posts: 36
Springfield VA
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GTXOnsfri Offline OP
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Forgot to say the radiator is still factory on the intake and exit, both on the driver side. I know newer radiators use more cross flow. This is the US Radiator Desert Cooler Aluminum 2 rows 2 1/4 thickness.

Re: Idle temp airflow or tuneup? [Re: GTXOnsfri] #2678977
07/19/19 08:49 AM
07/19/19 08:49 AM
Joined: Mar 2006
Posts: 117
Maryland
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mrob Offline
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This may be due to a missing baffle in the top radiator tank. Take off the radiator cap (when it's cold of course) and look down into the radiator. Can you see the top of the tubes or is there a baffle in there? I only mention this because you said this is a radiator form US Rad with inlet/outlets on the left hand side.

If there's no baffle, then I think the problem is due to uneven coolant distribution through the core. I fought this problem for quite a while in a similar situation (71 Challenger R/T with std cooling). My US Rad radiator did not have the baffle in the top tank, so more of the coolant flowed through the left hand side of the core (where the inlet/outlets are). That effectively reduced the heat transfer area at idle and the motor chronically ran hot at idle. I tried various fans and none made much of a difference.

My solution was to go to a radiator shop and have a baffle installed in the top tank. After installing the baffle, the problem went away. What the baffle does is to distribute the coolant more evenly across the top of the core. That way more of the tubes expose coolant to the airflow.

Another way to check is by using an IR temp gun. Measure the temps of tubes across the core. If the temps are higher on the left hand side of the core, then you know that's where more of the coolant is flowing. Ideally, the temps are fairly equal across the core. Hotter at the top and cooler at the bottom.

Hope this helps.

Re: Idle temp airflow or tuneup? [Re: GTXOnsfri] #2678980
07/19/19 09:03 AM
07/19/19 09:03 AM
Joined: Feb 2010
Posts: 1,387
Phila. Pa.
Mattax Offline
pro stock
Mattax  Offline
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Joined: Feb 2010
Posts: 1,387
Phila. Pa.
A couple ideas that may be worth exploring.
17* at 800 rpm should be OK. If that's distributor controlled, be sure that it stays at 17* below 800 rpm.
You could try a tad richer at at idle. pre-smog era 13.2:1 would not be unusual.
What I was going to suggest as an experiment was adding advance when the coolant temperatures go above 220 or so. That's what was done on some late smog era vehicles. For example my stock '85 AMC idles at 12* BTC, 650 rpm but when a temperature control switch (HD-CTO) sees the coolant is 220 F its lets manifold vavuum to the distributor advance.

One point of the above experiment would be to see if the source of the problem is excessive heat being put into the block by late timing.

My guess is more likely the heat isn't being carried out of the coolant at idle. So the problem is either the radiator to water or air to radiator heat exchange.

I know from the shop manuals and the parts books there were different diameter and different pitch fans. IIRC there's and 18 and an 18.5" diameter. Need the one that fits tightests to the fan shroud. The pre-70 fan blades were notched to clear the bubble top tanks. I would like to think that the repop radiator has similar heat exchange characteristics to an original - but I don't know that's true.

My guess is its air flow issue or heat exhange with the air, but would keep all the other possibilities open until proven otherwise. really hard to test directly - would need a data logger and two thermistors to see if the air is heating up or not as it goes through the radiator at idle vs. on the road. But if access to such things, then that
's what I'd do. Actually even one air probe would work - you can assume the outside air temp.

Pictured below is an 18" for use clutched drive

IMG_5227.JPGIMG_5244.JPGIMG_5242.JPG
Re: Idle temp airflow or tuneup? [Re: Mattax] #2678988
07/19/19 09:29 AM
07/19/19 09:29 AM
Joined: Aug 2006
Posts: 1,986
God's Country Maryland
GODSCOUNTRY340 Offline
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GODSCOUNTRY340  Offline
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God's Country Maryland
That's a very shallow shroud, the fan may be just pulling air from around it. Try mocking up a deeper one using cardboard around it (temporarily) to make the fan suck air through the radiator at idle. If it runs cooler you've found the problem.


I love the smell of Deer guts in the morning, it smells like... VICTORY!
Re: Idle temp airflow or tuneup? [Re: GODSCOUNTRY340] #2679010
07/19/19 09:56 AM
07/19/19 09:56 AM
Joined: Jun 2008
Posts: 2,952
usa
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lewtot184 Offline
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lewtot184  Offline
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usa
i had a 440 source water pump in my '69 coronet r/t stocker which is an edelbrock clone. my car always ran hot (all iron and 22" radiator) but ran exceptionally hot with that style of water pump. I installed a 6 blade (large diameter blades with an anti-cavitation plate) pump in place of the 440 source and the water temps went down 15-20 degrees. I think those edelbrock/440 source pumps are garbage. there's a 10 blade pump out there; I think flow-cooler.

Re: Idle temp airflow or tuneup? [Re: Mattax] #2679030
07/19/19 10:44 AM
07/19/19 10:44 AM
Joined: Feb 2010
Posts: 1,387
Phila. Pa.
Mattax Offline
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Mattax  Offline
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Phila. Pa.
Definately want to have the matching parts.
Looks like three different radiators with three different fans could have come with 440 auto in '68.
Your car has no A/C now, but if using the small diameter a/c water pump, it needs the matching pulley ratio and probably the taller, deeper, fan and matching radiator.
https://board.moparts.org/ubbthread...-stamp-vs-metal-stamped-part-number.html

1969 radiator p/n are different. shruggy
https://board.moparts.org/ubbthread...emi-charger-radiator-fan-215-or-216.html

Also interesting is that the Police cars got a different radiator. They might flow more or have higher capacity??

68-cooling-marked.jpg
Last edited by Mattax; 07/19/19 10:49 AM.
Re: Idle temp airflow or tuneup? [Re: Mattax] #2679039
07/19/19 11:12 AM
07/19/19 11:12 AM
Joined: Jun 2008
Posts: 2,952
usa
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lewtot184 Offline
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usa
on my r/t I've found very little change in temps with different fans; almost nothing there. the water pump did make a difference. 4 row radiators make a difference, but currently i'm using a 3 row (factory was 2 row with only 76 tubes!!!!!!!). cast iron exhaust manifolds will easily go 700-800f at their outlets. all that heat has to radiate/ transfer somewhere. unless the 22" radiator has a good core with a bunch of tubes, air circulates under the hood easily, they'll always run on the warm side with a big block. I have a '65 coronet with a 4 row brass radiator ( 204 tubes), tubing exhaust, 6 blade pump with anti-cavitation, good air circulation and it never runs hot.

Re: Idle temp airflow or tuneup? [Re: Mattax] #2682187
07/28/19 11:39 PM
07/28/19 11:39 PM
Joined: Jan 2003
Posts: 5,716
Hamilton, Ontario Canada
Magnum Offline
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Magnum  Offline
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Hamilton, Ontario Canada
Originally Posted by Mattax
For example my stock '85 AMC idles at 12* BTC, 650 rpm but when a temperature control switch (HD-CTO) sees the coolant is 220 F its lets manifold vavuum to the distributor advance.





I have always been a believer in manifold vacuum advance so an engine can idle and cruise above initial timing, which is typically a small number like 5 to 10 degress. This just confirms more is better.

Although a few degrees of timing should NOT change an engine from overheating to normal. If it does, it was on the edge in the 1st place.


As for GTXOsnfri, heat during idle generally is fan. Do you feel alot of heat being blown through the radiator by the fan?


69 Super Bee, 93 Mustang LX, 04 Allure Super

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