Overheating

[cudabob496]

I have a 72 service manual for my Cuda. It lists possible causes of overheating: blocked radiator air passages, incorrect timing, low engine oil, incorrect valve timing, bad temp gauge, restricted overflow tube, faulty rad cap, frozen heat control valve, dragging brakes, excessive engine idle, frozen coolant, faulty fan drive, faulty temp sending unit, faulty vacuum bypass valve, overfilling, insufficient corrosion inhibiter, blown head gasket, broken or shifted lower hose spring, low coolant level, collapsed rad hose, fan belt lose, glazed, or oily, air leak through bottom hose, bad thermostat, water pump impeller broken or lose, restricted rad water passages or restricted engine water jacket.

[miketyler]

wow - that covers the whole gambit I think. What about crankase ventilation? I just put those MP valvecovers on and am runing a PCV on the drivers side and a breather on the passenger side. When the engine is running there is vacuum at the breather grommet. Is that the correct setup and if not, is that contributing to my overheat condition?

[Mopar73340]

wow - that covers the whole gambit I think. What about crankase ventilation? I just put those MP valvecovers on and am runing a PCV on the drivers side and a breather on the passenger side. When the engine is running there is vacuum at the breather grommet. Is that the correct setup and if not, is that contributing to my overheat condition?

Unless your PCV valve is stuck in the open position there shouldn't be a problem. There should be vacuum on one of the valve covers (pcv valve) and suction (breather) on the opposite side to draw crankcase gasses out to be reburned. Your most likely cause of overheating are the electric fans, (assuming your timing is correct). I put dual electric fans on my 5.2 Dakota years ago and it was all they could do to maintain whatever temp it was at. They ran constantly. I put the factory clutch fan back on it. The factory 7 blade fan and HD thermal clutch with a shroud cannot be beat for moving air. Just my 

[miketyler]

yeah, I hear you. I did some testing previous with the factory shroud and the original 7 blade fan and spacer block and it only had marginal decreases in temp. I do have a 3row radiator now and I was hoping that I could retain the dual electric fans. My ceramic headers are now a flat grey color and my plugs are a light tan. Before I abort the electic fans, I wanted to make sure I had ruled out all else.

I have two correct thermoquads for the car. One was redone by DemonSizzler. I was going to try one of them and see if it affected temps. The engine is all stock. I just dont see why it wants to run as warm as it does. Will ck vacuum leaks, timing, and finally the carb as I was going to go there anyway. the Holley SA I am running on it now is ok but was looking for something with better mileage. I would gladly sacrifice mileage for a cooler running mill you know.           

[miketyler]

How can I tell for sure that my overheating is from running lean?  My plugs look tan, but dont look white. I have an IR thermometer. Can you look for excesive temps on the surface of the headers where it exits the head? 

[Chryco Psycho]

if the plugs are tan you are close , where is the timing set

[miketyler]

Book says 2.5^o BTC @700 RPM with VA disconnected. I am setting it at that spec and will drive it around and test. Does that idle RPM sound right for an automatic car?  Its a 340 with stock 340 cam.

[matt63]

From what I can gather, electric fans struggle to move enough air.  They seem to work on large aluminum rads with great cooling capacity.  I was advised to try an electric pusher auxiliary fan on the front of my rad so this is one option to increase cooling capacity.  Timing should be at least 12 to 16 deg BTDC. 

[miketyler]

From what I can gather, electric fans struggle to move enough air.  They seem to work on large aluminum rads with great cooling capacity.  I was advised to try an electric pusher auxiliary fan on the front of my rad so this is one option to increase cooling capacity.  Timing should be at least 12 to 16 deg BTDC.

Yes, I may still have CFM issues with the dual electric fans and 26" 3-row radiator. I need to be sure she's timed up right. 12-16 BTDC? Is that at idle with VA disconnected? I got the 2.5 BTDC specs from the Imperial-Barracuda manual. Where are the 12-16 BTDC specs advertised? Maybe I'm looking in the wrong place?  

[Chryco Psycho]

move the timing to 16* & leave the vacumm disconnected or adjust it most of the way off with an allen wrench in the vacuum pot it will run better 

[miketyler]

will 16^oadd to my overheating? Also, set the timing at 700rpm idle speed?

[MEK-Dangerfield]

will 16^oadd to my overheating? Also, set the timing at 700rpm idle speed?

Mike,

  forget the factory manual settings. Chryco is right in the 12-16* BTDC range. This is set at idle with the vacuum advance line unplugged from the distributor. I'm in the 13-14* range. Any more than that, and mine pings, or misses. It runs real cool though. My temp gauge doesn't go above 1/4 of the way up.


  Mike

[miketyler]

Ha! Maybe thats the key?? So were the engineers at the factory thinking when they developed the spec to be closer to 0^o? Sorry for all the questions, I just have to know the theory behind all this.       

[MEK-Dangerfield]

Ha! Maybe thats the key?? So were the engineers at the factory thinking when they developed the spec to be closer to 0^o? Sorry for all the questions, I just have to know the theory behind all this.       

If you have a bigger cam and such, then the timing changes. All I know is, if I set my timing to 6* BTDC, my car isn't starting the next time. 

  Mike

[miketyler]

my engine is a stock 340 w/stock cam. I just wonder if my 340 will choke on the 12-16^oBTDC? I'll try it and see what happens.