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Old 04-17-2002, 07:44 AM
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Post cooling

I just put in a 1969 400bb rebuilt with a little cam, my problem is, I never had a cooling problem till now!
I was running a stock 301. but since I changed engines I am running at 240 degrees f.
i removed the thermostat and she runs cooler for a while then heats up to 240 in about 15 mins.
WHAT NOW? No air pockets! no thermostat!And it still heats up! HELP!!!

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Old 04-17-2002, 08:28 AM
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There is a bunch of things that can be wrong with cooling. One of the first things to look at is the radiator. Have it flushed, recored or my favorite fix, replace with a 2 core alum. You could have a plugged water jacket or even a head gasket missing a hole. What about the fans? Do you run electric or use belt driven? I like to use a flex fan with an electric set to come on at 200d. Evenm check to see if you have good airflow from the front of the vehicle, I have seen bad AC condensers cause overheating. The thing I hate about cooling problems is it's either an easy fix or a big job.
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Old 04-17-2002, 08:59 AM
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Cool

first of all put stat back in you could cut the center out of it you need some kind of restiction I agree with the other fella do you have a shroud on it you could also try one of those high flow plastic fans I found they seem to work well just a few simple ideals hope its not major good luck
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Old 04-17-2002, 09:19 AM
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I'm not an expert in this area, but have read many posts to the effect that you need to have a restriction in the water line at the thermostat if you take it out. I would guess that the restriction insures that all the various pockets in the block get filled with cooled water that is under pressure.

Next, for sure you need to have a fan shroud to assure that you are using the cool air to cool the radiator, otherwise you will get only the benefit of the air that is immediately in front of the fan, partiularly at idle or low driving speeds.

You need to have a clean radiator that is not self insulated from the inside.

Finally, the radiator needs to be sized appropriately. Maybe the radiator just cannot handle the larger motor. I don't know what radiator you are using, but see if the car ever had a big block as stock and see if the radiator is the same as would have been available then.
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Old 04-17-2002, 10:18 AM
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Im not positive ether but my thinking is to hold back water in the radiator for the air to cool it never really thought of the pockets could be

[ April 17, 2002: Message edited by: wrenchturner ]</p>
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Old 04-17-2002, 12:00 PM
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You also need a thermostat or restriction so the coolant doesn't flow too quickly through the radiator core. It will lose more heat if it has that extra time in the core with air moving past it. I had the same problem with a 350. I re-adjusted the timing and it seemed to help a little but the ultimate fix was a new water pump. Sometimes the simple things get you. If you do install a thermostatically controlled electric fan, the temperature bulb actually gets squeezed between the radiator fins, it wont work if it's inserted at the bleed valve. For some reason it wont get hot enough down there. Good luck.


A.J.
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Old 04-17-2002, 12:41 PM
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going from a 301 to 400 you need a larger radiator rather more cores probably 3-4 cores, you should have a spacer to bring fan 2-inches from radiator or closer also a schroud, a 195 degree thermostat and a multi blade fan no plastic
or fiberglass, If you have a electric fan different, also on 400's they had radiator top brace
to force air into radiator instead of over top of radiator, I like factory stuff myself, tour not trying a hit or miss thing.If your in a high humity,and low altitude area tourque heads 20 lbs more or when overheating your going to blow a head gasket.hope this helps T.
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Old 04-17-2002, 02:28 PM
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Cool

[ April 17, 2002: Message edited by: wrenchturner ]

[ April 20, 2002: Message edited by: wrenchturner ]</p>
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Old 04-21-2002, 11:34 PM
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Seems to me that this is a common problem that can be avoided with a little planning. Your not the first and I doubt you'll be the last(no offense) Thermostats are restrictors, they hold back water flow for initial warmup then slow water flow for maximum cooling in the radiator. An old or worn water pump will not flow properly and cause overheating. the radiator is no more than a heat exchanger in which air flow is also crucial.Any air flow obstruction is a bad thing. also, shrouding is critical at slow vehicle speed. I am a firm believer in extra fins in your radiator core vs more tube rows (more fins remove more heat,faster).......good luck
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