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Running hot highway only

Coronet67guy

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So I got the TTI headers in my 74 Charger. Rear end 3.23 with sure grip. Everything was fine around 40-50 mph during initial break inn. First time on highway it didn't take it long to peg on the H side. Wish I had a gauge to tell the exact temp but never seen the car run near this hot.

Lower hose collapse or radiator flow doesn't make sense since neither was a problem before the headers. Are the extra RPM's requiring more water flow? The radiator is new but a cheap Duralast B509 from Autozone. I should get a quality radiator in the car. What's everyone running in a big block for a radiator? The Griffin 5-70070 says it's an exact fit don't really want to spend 800 on a radiator. Would a high flow water pump make sense? Can runs cool in town, only gets hot at highway speeds. Thanks for any input.
 
Start with the basics first. Did your thermostat open? What thermostat is in the car? What fan setup is in the car? I was having heat problems when I moved to North Carolina. The summer heat was too much for my 11 to 1 440. I switched to a Champion exact fit aluminum radiator, Flowkooler water pump and an electric fan setup. No more overheating problems.

https://shop.championcooling.com/Performance-Radiators/Dodge

https://flowkoolerwaterpumps.com/co...rysler-dodge-plymouth-hemi-hi-flow-water-pump
 
The radiator is new but a cheap Duralast B509 from Autozone.
Only buy "dumb" parts like bulbs, fluids, wiper blades etc from AZ. Their parts are not called "Don'tLast" for nothing. It's all cheap Chinese junk. That's how they can offer a lifetime warranty. Personally, that's where I'd start.
 
Could be the engine is running lean , they can do that after installing a good free flowing exhaust - Get her hot and read the plugs. Better yet get a wideband a/f gauge and weld the bung in one of the collectors that will give you a constant air fuel reading.
If your running a 440 I would run a 26 inch radiator
 
Start with the basics first. Did your thermostat open? What thermostat is in the car? What fan setup is in the car? I was having heat problems when I moved to North Carolina. The summer heat was too much for my 11 to 1 440. I switched to a Champion exact fit aluminum radiator, Flowkooler water pump and an electric fan setup. No more overheating problems.

https://shop.championcooling.com/Performance-Radiators/Dodge

https://flowkoolerwaterpumps.com/co...rysler-dodge-plymouth-hemi-hi-flow-water-pump

Thanks for the links. I can't remember for sure but I think I dropped a 180 in this. Stock fan and clutch. I'm assuming stock water pump. I'm sure a high flow would help the cause.
 
Only buy "dumb" parts like bulbs, fluids, wiper blades etc from AZ. Their parts are not called "Don'tLast" for nothing. It's all cheap Chinese junk. That's how they can offer a lifetime warranty. Personally, that's where I'd start.

Agree. Previous owner had the completely wrong radiator on the car with the top hose on the drivers side. It wasn't meant to be a long term solution but seemed to be doing the job till this running hot issue yesterday. Thanks.
 
Could be the engine is running lean , they can do that after installing a good free flowing exhaust - Get her hot and read the plugs. Better yet get a wideband a/f gauge and weld the bung in one of the collectors that will give you a constant air fuel reading.
If your running a 440 I would run a 26 inch radiator

Thanks for the suggestion. I hadn't thought about that. Running a 400, I believe the radiator I dropped in is the stock 28 inch width. Any a/f meter you would recommend? Jeg's had a bunch of them.
 
Thanks for the links. I can't remember for sure but I think I dropped a 180 in this. Stock fan and clutch. I'm assuming stock water pump. I'm sure a high flow would help the cause.

Curious, did you get the fan package from Champion or purchase a different fan set up? I'm looking at the champion radiator upgrading to 3 row, just not sure about the fan. I've never ran an electric fan in any vehicle so complete novice about what works best.
 
FlowKooler water pump is a good move. Saw a big difference on my 383 when I went that route. I'm still running with the stock radiator. They do suggest using a hi flow type thermostat with their pump.
I bought the PLX a/f unit, installed the weld in bung on ex pipe with the optional plug. I only install the O2 sensor temporarily when tuning the carb and such. Run the wire thru the window and get power from lighter socket. If you get the blue tooth option, there is nice app that pairs with your I phone to the a/f unit and gives the readings on your phone.
 
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Overheating on the highway , take your factory fan and shroud out of the equation

You already have airflow at 65 70 75 mph

And you said it cools fine in town , where your fan and shroud enter the equation


Buy yourself a cheap infrared thermometer - When it starts getting hot on the highway can you pull over and start pointing at the water pump , lower and upper radiator hoses , thermostat housing etc. and different areas on the radiator
 
Typically an overheating problem at highway speeds only is a coolant flow problem...think radiator,water pump, possibly a stuck partially open therm.
 
Overheating on the highway , take your factory fan and shroud out of the equation

You already have airflow at 65 70 75 mph

And you said it cools fine in town , where your fan and shroud enter the equation


Buy yourself a cheap infrared thermometer - When it starts getting hot on the highway can you pull over and start pointing at the water pump , lower and upper radiator hoses , thermostat housing etc. and different areas on the radiator

I have one of those already, so I'll be sure to toss it in the car next time I hit the highway. I'm assuming I should see the lower hose about 20 degrees cooler than the upper??
 
Could be the engine is running lean , they can do that after installing a good free flowing exhaust - Get her hot and read the plugs. Better yet get a wideband a/f gauge and weld the bung in one of the collectors that will give you a constant air fuel reading.
If your running a 440 I would run a 26 inch radiator

Just curious here, I hadn't thought about the lean condition and I'll ask the guy who installed the headers if he checked the ratio, but would running lean cause the car to be hot on the highway but not at lower speeds??
 
The long and short of it is that your new radiator doesn't have the cooling capacity to cool the engine at highway speeds (cheap does not equal good!), the shroud or any other factor isn't going to change anything..
 
The long and short of it is that your new radiator doesn't have the cooling capacity to cool the engine at highway speeds (cheap does not equal good!), the shroud or any other factor isn't going to change anything..

Agree, except the same radiator kept the car cool before the headers on the highway. Having said that the Flowkooler has been ordered and I'm looking at at least a 3rd row champion. May even upgrade to the four row. All that with a new RobertShaw hi flow thermostat and I'm thinking my problems will be gone.
 
I saw a car with a cold case radiator at Carlisle.
It was very sharp looking.
 
I don't get what the header install could have changed!?

Me ether, also did a gear swap and went to a sure grip. Increased RPM that just exceeded what the system could handle? Or maybe just crazy timing and the thermostat or water pump is crapping out on me.
 
I think the gear change is much more likely to cause your problem than the headers. How much change? 2.94 to 3.55?
I agree with kilrbee, whatever was responsible for the change, it looks like you dont have enough radiator.
As for what i use.... with a 500hp 440, i use a high fpi (fins per inch) 26" (or maybe it's 28?) big block copper/brass cordoba radiator, factory shroud, cheap garbage flex fan, and a pusher electric from the boneyard, with a trans cooler in front of the radiator. The electic is for temp cooldown after a pass, but it's only neccessary on hot race days. If i cool down before a lap, i can get back to the pit at 170. The car usually runs 180-185 on the highway with 3.91s.
 
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