1969 Road runner overheating problem

72duster72 · May 8, 2022

I have a 69 Plymouth Road Runner pro touring. 522 with a six pack fuel injection. I live about 6000 feet elevation. It is running about 11.3 compression. I can drive the car for about 20 minutes and will spike the needle at 250°. It’s been tuned. I have a griffin radiator with two electric fans I do have an SDc pulley system I’ve change the water pump pulley to a smaller pulley to spin water pump faster no change I’m just running out of options. My next option is to takeoff the condenser for the AC and see if that helps cooling.I’m running about 190° thermostat,running Evans cooling fluid. Thanks for any help

chtampa · May 8, 2022

I would start with a Temp gun and check out each part. Thermostat, Temp sending Unit, Fan Switches, Gauge. You have moved the right direction with most of what you have. Aftermarket heads? Correct A/F ratio? Shroud?

diesel_lv · May 8, 2022

I have a 496 w 10.2:1 in '67 Coronet 4dr. I live at 500' and summer temps of 125°. A/C on my car. Running SD concepts also. I am using an Entropy 2 row aluminum radiator. Each row is a true 1.25" with 1/4" between making core 2.75" thick. I'm running a Flowkooler w/p. I could not make any electric fan combination keep it cool. Tried 3 custom shrouds and 3 sets of fans in different combinations. None worked. Found a 19" 11 blade nylon fan from a Chevy 496 designed for reverse rotation. Obviously no room for fan clutch. SD made me a custom spacer for between the pulley and fan. It fits inside factory shroud, clears pullies by about 1/8". W a 180° thermostat, it now cruises at 80mph at 176°, stop n go at 196° and stopped, idling for 10 minutes peaking at 222° then coming back down slowly. 2 bottles of Waterweter then 50/50 coolant n distilled water.

72duster72 · May 9, 2022

Do you remember what type of vehicle you got that reverse rotation fan off of. I run 190° thermostat because I was told Phil injection is a little hotter to properly work. Thanks

Bonehead70GeTeX · May 9, 2022

I put lager radiator , and clutch fan ,, the clutch is part # is for a 80s Jaguar ,, there’s a old post about it , I just can’t find it ,

max340 · May 9, 2022

If it stays cool while your driving and overheats at a stop light then take off the electric fans and put on a seven blade clutch or fixed fan with a shroud. Bonehead70GeTeX is correct.

72duster72 · May 9, 2022

It overheats as it’s driving. I’m trying to do my best to keep the pulley system I have because it cost me a lot of money but I can’t drive the car May been a waste of money. May have to go to a standard belt system with a fixed fan

diesel_lv · May 9, 2022

72duster72 said:
Do you remember what type of vehicle you got that reverse rotation fan off of. I run 190° thermostat because I was told Phil injection is a little hotter to properly work. Thanks

I saved a couple screen shots and I'm pretty sure this is the one. I run fuel injection, Fitech, and it needs 170° to go into closed loop and start learning. But that parameter can be changed. I set mine to 150° as my engine runs as cool as it does. Won't get over 154° when temps are 80 or less outside. Mine would idle and slow drive just fine w electrics and overheat at anything over 45.

72duster72 · May 9, 2022

Thanks that is great I will contact Sd Concepts about that spacer. And maybe I’ll remove the fans and put a shroud

72duster72 · May 9, 2022

You have it hooked to the water pump? Your pulley system looks different than mine.

chtampa · May 9, 2022

I was explained to me that if it cools at speed it is an airflow/radiator issue. If hot no matter what it is in the engine.

diesel_lv · May 9, 2022

72duster72 said:
You have it hooked to the water pump? Your pulley system looks different than mine.View attachment 1282501

Yes, I have their early version that kept a/c in original location. But the face of all the pullies is still in same location. The closest one the fan comes to is the a/c compressor.

72duster72 · May 9, 2022

Thanks

72duster72 · May 9, 2022

Did you make a shroud? If so any pictures thanks

diesel_lv · May 9, 2022

72duster72 said:
Did you make a shroud? If so any pictures thanks

I used the factory shroud. If you don't have one, Mancini sells a Mopar authorized reproduction. If you look at the pics of the fan, you can see a little black mark on some of the blades. I had to measure each blade and grind the exact same off of each at that angle to clearance the bottom of the shroud. I'll see if I can get that measurement for you soon.

72duster72 · May 9, 2022

chtampa said:
I was explained to me that if it cools at speed it is an airflow/radiator issue. If hot no matter what it is in the engine.

That’s what’s bothering me everything is new on this engine I have maybe couple hundred miles on everything. Maybe 11.3 compression ratio is too high even though I’m at 6000 elevation and running aluminum head.

diesel_lv · May 9, 2022

What water pump are you using? Since you're reverse rotation, does it have the backing plate? What is your timing set at w that high of compression? What brand e-fans are you using and size? Shroud or no shroud on them?

72duster72 · May 9, 2022

Water pump flowkool . I had the Mopar performance with the backing plate no difference I’ve changed to a smaller pulley just recently no different. timing I couldn’t tell you it was Dyno tuned. I thought the timing also but it made no difference when I had it tuned. Maybe it’s just a hot motor maybe only geared for drag racing not an every day driver.

diesel_lv · May 9, 2022

What brand, size e-fans? Shroud or no shroud on fans?

72duster72 · May 9, 2022

Electric fans do you have a shroud. I believe they’re either oh 11 inch inch about the whole package from Griffin radiators

1969 Road runner overheating problem

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