Over heating while at idle

[2BWIRED]

So this car had an overheating issue while idling. It would keep climbing on temp up to 220 which is where I would shut it down if I could not get moving to cool it down. Upon inspection I noticed the fan shroud was poorly installed and only a zip tie was holding it on. It was also not close to the radiator. When I was working on fixing it I noticed it had a gap top and bottom so I bought some rubber car door seal to make it seal tight to the radiator. That significantly improved the cooling although not completely. I also noticed the fan was close to the radiator and not sitting back a little bit from the shroud. They had a 1" spacer so I installed a 1/2' spacer. The fan is now sitting almost 1/2 way out from the shroud. I bought an anemometer just to see what it was pulling for air. I measured 7.5 to 8 mph may or may not be the way to measure it but it doesn't seem to pull a lot compared to one of my other cars. I checked the other car and it was 15 mph and had a lot more draw. This car has a 7 blade non clutch fan on it now. The idle is low like 700 rpm, so I bumped it to 900 rpm and then set it to 1100. At 1100 its 12 to 13 mph fan pulling and seems to pull air flow better. I have a smaller pulley to install on the water pump so I might try this as well. It is a water Pump Pulley - V-Belt - 2 Groove - 5.813 in Diameter - Aluminum - Black Anodized - Mopar B / RB-Series / 426 Hemi. I think it will fit but have not installed it yet. I was also going to install external trans cooler. Timing seems right and plugs do not look lean. I have not installed the afr probe or gauge yet. I am also planning on changing thermostat and temp gauge just to make sure. It has an aluminum 3 row radiator in it now and it should cool it. Just giving some tips and ideas I have had and seem to be going in the right direction. The car has a stroked 440 to 496 and is making 617 hp in a 67 satellite.

 

[2quick]

What's the idle timing?

 

[super-bee_ski]

First off...the car is designed to run about 210-220.
Many become obsessed with the 165-180 degree temps but I'm quite certain the cars back then ran a bit hotter by design.
Remember a 3% variation in Thermometer accuracy.
But, If I remember correctly:
1. Temp climbs when car is at idle...Waterpump.
2. Temp climbs while driving, Coolant flow restriction/perhaps radiator, as more air flows through, fan is not needed.
I am not as smart as I used to be...so, lets see what others say.
Do you have a fan shroud?

 

[2quick]

MY 860hp 572 runs 167-170 all day long, even at 90+ degree outside temp. If it ever gets to 180, its after spirited driving and gets back down to 167 within 30 sec or so...I run a huge Wizard radiator, Meziere 155gpm water pump, and brushless wizard fans. I would try and add some idle timing about 5 degrees at a time and watch the temp gauge. I understand this will affect overall timing (I run holley EFI so I have no limitations) but at least you know if it helps or not and can adjust advance with that understanding. Or just lock it out at 35degrees all the time and see what happens. Yes it will probably kick back when starting. This is for diagnosis only. please verify your temp gauge also.

 

[Geoff 2]

It is no fun watching that needle climbing, climbing, climbing......hitting 220*....& wondering if it is going to stop.

If this is a NA engine making 617 hp, it must have a sizeable cam in it. Bigger cams need a LOOOOT of timing at idle to improve combustion....& stay cool. As much as 50*. Without knowing more about the engine & cam specs, it is hard & fast rule about the exact amount of idle timing reqd.

There is no hard & fast rule whether it is airflow....or water flow causing the problem. Could be either/or & changing one might fix the problem. Sometimes small changes/improvements add up. Do 4 things that reduce temp by 5* each & there is a 20* reduction.
The water pump should be overdriven by 10-20%. Also, a pump impeller that has open blades is very inefficient. It just churns up the water without capturing it & pumping it through the engine.
More info here: www.stewartcomponents.com

 

[Rishi]

As others may suggest, don't overthink this (something I do TOO much) or obsess on what you're seeing.

We may all agree: When the cooling system "is great" it will keep the engine cool at idle. Period.

Bear in mind, "at idle" is the LEAST efficient cooling scenario, because the air forced through the radiator (and around the engine) at highway (cruising) speeds is much better at keeping things cool, than when stationary at idle, and relying solely on the fan to pull air through the radiator.

The fan shroud works best at highway speeds. Smallish (1/2-inch) gaps between the shroud and the radiator exact small (single digit losses in) percentage points of cooling efficiency. These gaps do NOT (in my opinion) impart a significant loss to worry about. but, improve them if you can.

Longer duration cams and engine timing are big factors in how much heat the engine makes at idle. Your engine is designed to be run at 220F-235F. By comparison, Formula 1 engines are designed to run at (coolant temperature) 250F.

Is your cooling system ideal? Maybe not. If you're concerned about being caught in traffic, and your engine over-heating, then I support your concern, and desire to make things better.

How to make cooling better? Presuming the OE systems (thermostat, water pump, water passages) are functioning properly, the first order of business is the radiator. If its not among the more efficient modern-day cores, this may be something you can resolve by pulling the radiator, and having it checked out by a reputable radiator shop (these are slowly disappearing.)

If engine cooling (at idle) is more important than engine performance, understand advancing the timing increases the combustion temperature (in the cylinders) compared to retarding the timing to increase temperatures in the exhaust.

A 50+ mile engine flush can also also remove casting sand, and other restrictive elements from the engine block, drastically improving cooling efficiency. I once replaced nearly all of the freeze plugs in an engine, and used a pressure washer to blow out all of the passages, because casting sand was coming out of the engine. By the time this was exhausted, the freeze plugs in place, and the engine back on the road, I was shocked by how much cooler than engine ran. In fact, I had to adjust the bimetal choke to bring things back to normalcy.