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I have a 66 coupe with a 289 that has a mild cam in it. I have changed the water pump and the thermostat and it's still overheating. What else can I do to fix this problem or what is still making it overheat.
 

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You should replace the radiator cap. If the cap does not hold enough pressure then the coolant will boil sooner at lower pressures. You may also need a 4 core radaitor since you are making more power which in turn creates more heat. Have you flushed the system and how old are the hoses?
 
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Need more info. What type rad is in it now? Have a fan shroud? Carb set too lean?
Timing? When does it overheat? Checked the fan clutch? Details man, details.
 
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I have a 4 core rad. No shroud. Couldn't tell you if the carb is set too lean. I haven't checked my timing although I don't think that's my problem or is it?. There is no fan clutch. Any other info you need doc?
 
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Timing too far advanced will make it run hot. Generally at speed with idle ok.
When does it overheat? Sitting at idle, stop and go, or highway?
 
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It overheats sitting at idle and stop & go but not on highway. I guess I can have the timing checked. Anything else I should check or do?
 

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I would also check the flow in the radiator. If there is any blockage you may need to have the radiator serviced.

Scott
 
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The rad is clean and farely new. There is no crud inside as far as I can tell. I have flushed it several times just to make sure that was not the problem. Also someone suggested that I should drill a 1/8th hole on the thermostat to get rid of any air that was stuck inside the motor or rad? Any comments the thermostat?
 
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Ok, if it's fine at highway speed then timing and jetting should be ok.
Also it's getting all the air it needs thru the rad for cooling and your
getting coolant flow.
So at idle and stop and go, since you say you have no shroud you might
want to check on getting one as trust me they really help. You said fan has
no clutch, after market?
 

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My only thought on the radiator is if there is a partial blockage, there would still be enough coolant and air flow at highway speed to keep the temp down. At idle or stop and go air flow is restricted and overheating can occur. I also agree with checking into a shroud as it should definately help.

Scott
 
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Discussion Starter #11
I picked up the water pump from a high perf. shop. They said it was a stock pump. It looked like the same one I replaced. I will get shroud if that helps. Anything else you might think of could be making it overheat?
 
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Without the shroud, the fan does more "beating" of the air than pulling, can pull from top, sides, bottom
instead of pulling thru the rad. With the correct shroud, one that encases the fan something like this,
http://www.mustangsteve.com/CarPics2.html, and i only use this as an example cause i remembered the
link, the fan has to pull thru the rad. Hope this helps.
 
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Discussion Starter #13
Thanks for the info everybody. So far I pretty much need to; check the thermostat, get a shroud, check the timing, replace the rad cap and hoses. Is that it or is there anything else?
 
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Discussion Starter #14
I had the EXACT same problem. It turned out that My "excellent condition" 4-year old radiator, which I flushed the hell out of, was shot!!! Rust and scale from the engine had blocked enough of the tubes for a long enough time, that it was quite inefficient. Pull the radiator out, bring it somewhere, get it cleaned and checked. Worth the money, and then you'll know.
Just my .02
T
 

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I ran into this same thing.. Turns out it was a old temp gauge reading hot. Installed an aftermarket gauge and it never reads abovr 190.. I checked the gauge before I put in by sticking the end in a pot of boiling water. Checked out ok... May want to be sure it is really that hot in there. Plus I hear watter wetter helps.
 
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