72 Dodge Demon Overheating

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lisapenn62

lisapenn62

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Waynesville, Ohio
I have a 72 Dodge Demon with a 340 bored 30 over. It's got 10 1/2 to 1 pistons, holley stripped dominator intake highrise, running a 750 dual line holley. I have a 3 core radiator, 180 degree thermostat and I believe a high flow water pump and two fans, one mechanical and one electrical. I am still hitting 210 within about 1/2 hour with the car idling. Anybody have any ideas?
 
radiator partial pluged, or not enough air flow, 210 is not overheating if your letting it idle for half an hour
 
If your electric fan is not off set from your main fan it will not allow enough air to flow.Next do you have a fan shroud ? if you do the fan needs to have 7/8 of fan in shroud and 1/8 to 1/4 sticking out this allows more air to flow.
 
Does it stabilize at 210 after 1/2hr? So your slowly building temp to 210? I'd say that if you dont have a shroud, try that....otherwise your engine fan is really just blowing hot air around the engine compartment.

Is your elec. fan a pusher or puller? Mounted on the outside or inside of your rad? It could be blocking some air that the engine fan is trying to pull in at idle if it's not on too.

Last question, does it get to 210 with the elec fan running at idle too? If so, then I'd say you need to still try a shroud...not sure how big your elec fan is but a small one wont move much air depending on how it's wired...as a pusher it's even less airflow (cfm) than rated typically.

Really last question. Is the rad new? Been re-cored? You say 3 row...but how old is it? Copper/brass or alluminum? Lot's of factors here...
 
The electric fan is offset from the mechanical fan, but it still heats up and vapor locks even when driving down the road. The radiator is the original, copper that came with the car from the factory. Timing has been retarded thinking that it was running too fast and causing the car to overheat but that didn't correct it so timing is now set where it should be according to purple shaft cam that's in it. There is no shroud on it, haven't tried that yet but mechanical fan is within 1 1/2" from radiator.
 
lisapenn62 said:
The electric fan is offset from the mechanical fan, but it still heats up and vapor locks even when driving down the road. The radiator is the original, copper that came with the car from the factory. Timing has been retarded thinking that it was running too fast and causing the car to overheat but that didn't correct it so timing is now set where it should be according to purple shaft cam that's in it. There is no shroud on it, haven't tried that yet but mechanical fan is within 1 1/2" from radiator.
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Replace the thermostat with a new high flow one (trust me) and make sure you test it on the wifes stove and get the leading edges of your mechanical fan blades within 1inch of the core, I run mine at 3/4". By all means get a shroud especially for idling around town and make sure the lower rad hose has the spring inside it to keep the hose from collapsing at high RPM. When was the last time the rad was acid flushed.
 
I know when i got my demon the fan was to far from the rad and the air went around the rad instead of through the rad
 
I had the same problem with my dart. I had at first just a pusher fan, the car ran hot, 205-210 within no time. I installed a flex fan and still no differance. Then i put shroud on, now the car runs 180 all the time.
 
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