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Old 07-05-2003, 04:04 PM
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Help !!!!!!!! 400 Sbc Overheating Bad

I have a 400 SBC .30 over mild cam 750 edelbrock tourqer II alum intake 202 I 167 E 64cc runners Alum Rad with elec. fan only no thermosat only restricktor plate with 5/8 hole. the car will always run HOT !! 210,220, 230 hotter if I dont shut down , I can't get it to run cool timming is at 13 deg. ,,, 29 deg @ 3000 RPM. Can someone please help me I really want to enjoy my car but I can't even drive it , it heats up so bad, both city & hwy . I have tried water wetter , anti freeze , I need help please,,,

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Old 07-05-2003, 05:19 PM
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I'd try running a thermostat for starters. Here's a couple of quotes from Dave Emanuel:
Quote:
...it may be possible to install a 5/8 or 11/16 in. diamater restrictor in place of a thermostat, but for the majority of street and race engines, use of a thermostat is highly recommended.
so even for race engines a thermostat is a good idea...according to this guy.



Quote:
What actually happens is that when the thermostat is removed from a cooling system with a vertical radiator, the point of highest pressure in the system moves to the radiator tank. Consequently, normal operating pressure exceeds the capacity of the radiator cap spring, so the cap opens and allows coolant to escape-even though the engine is not overheating. But it doesn't take long for coolant loss to reach the point where there isn't enough left in the system to provide sufficient cooling. So it appears that unrestricted flow leads to overheating, which causes coolant to escape. However; what really occurs is that normal pressure causes the cap to lift which allows coolant to escape which leads to overheating.
-Check your coolant levels lately?
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Old 07-05-2003, 06:59 PM
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since you said your overheating in traffic and the highway. frist i would check your timming. sounds like your running lean. might have to reject your carb. second put a thermostat in. Do you have a shroud on the radiator? then i'd go with 50/50 mix with antifreeze.
Where is you temp sending unit located at? different parts of the motor will give you different readings.
What size is you elec fan? abd what CFM? to small of a fan will not cool the radiator in traffic. On the highway your fan dosn't do anything to cool the radiator.
What radiator cap you have on the radiator? (lbs)

what kind of car are you talking about. if it's an older one. when was the last time you flushed out the cooling system?
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Old 07-05-2003, 07:11 PM
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I agree with the thermostat being more desireable than a restrictor for street applications. However the part about the coolant escaping under pressure, they all do that, not just vertical flow radiators. This is considered normal, that's why modern cooling systems have a vacuum type pressure cap. As the coolant gets hot it expands and some gets expelled through the cap to a reservior. As the engine/coolant cools, it contracts and the vacuum created from this contraction draws coolant back into the radiator from the reservior through a one way/vacuum valve located in the cap. This maintains the coolant level.


Back to the original question, the heads you described on this motor, are they 400 heads? If not, have they had the steam holes drilled in them to work on a 400?
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Old 07-05-2003, 07:29 PM
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the car is a 1972 Vega , the timming is set good , the alum rad is 26 X 19 4 core HOWE , the elec fan is 16 inch , the rad is shrowded from the front to collect all the air from the fan, , the sending unit is mounted on the intake at the left front corner , the cooper line is thermo wraped in a hose along the rocker cover to the fire wall , the 750 cfm Edelbrock carb is factory set other than idol air mixture , the heads have been drilled with steam holes.

What temp of thermostat should I run ?

Could the jets be too high ,, ????

would that cause so much over heating, it runs rich at an idol ,

Please can someone help !!!!!
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Old 07-05-2003, 07:58 PM
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I'd go with a 165. but it really dosn't matter. the only difference between the 165 and the 195 is one opens up ealier. after both open up they will still read the same.

Here's a great web site about overheating.
www.inccn.net/techforum.htm

It will walk you through everything and explain why
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Old 07-06-2003, 03:29 AM
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Do your heads have the steam holes drilled in them?
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Old 07-06-2003, 03:47 AM
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Go to http://www.stewartcomponents.com (sorry I don't remember how to make links) Their site is very helpful. I followed his advise and cured my problems. I personally think their advise on overdriving the pump is one of their best tips!
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Old 07-19-2003, 11:59 AM
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Help !!!! Nasty Air Lock !!!!!!!!!!!!!!!!!!!!!

I have a 400 SBC that keeps burping water back out the rad I can't seem to get it out , I have let the car run 45 min with the hose in the rad & it just keeps burping out water & refilling & burping out , no heater core or hoses ,,
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Old 07-19-2003, 12:52 PM
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Do you have a coolant recovery system on it? If you are running with no pressure on the system, you will never get rid of the bubbles. Fill it with coolant (50-50 mix) & cap it up. Fill the overflow tank about half full of coolant. It should burp itself as you drive. If the overflow tank goes dry, put more coolant in it. I'm assuming your heads have the proper steam holes for use on the 400 block.
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Old 07-19-2003, 02:33 PM
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I agree. You need this "puke" tank for what it's for. I have seen one for the Corvette, and I'm sure it would be fine for your 400. If you need a pointer, then fine, but I think they are pretty easy to find.
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Old 07-19-2003, 08:45 PM
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400 Steam Holes

Can anyone please tell me if the steam holes were covered by the head gasket , would I always run hot to the point of boil over ?
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Old 07-19-2003, 08:48 PM
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I have no idea how chevys work but on a ford if you get the head gasket turned around it will block the water flow and make it run hot. Have you checked your thermostat?
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Old 07-19-2003, 09:14 PM
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Arrow

I believe it will run hot, they are supposed to help eliminate air pockets in the jackets.
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Old 07-19-2003, 09:29 PM
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Re: 400 Steam Holes

Quote:
Originally posted by Sampson
Can anyone please tell me if the steam holes were covered by the head gasket , would I always run hot to the point of boil over ?
I don't know if it will boil over for sure, but I wouldn't take the chance with a thin-walled 400.

I have a 400 myself, and I would highly recomend using Fel-Pro head gasket part #1004. Read the directions on it, and you will see that it tells you how to drill an extra cooling hole at the center of the block in order to equalize the temperature in a Chevy better.
The center two cylinder's exhaust valves are together and they actually heat up the block in the center more than the outside cylinders). This gasket also has the holes for a 400.
If you don't have this done already, it's worth a teardown to do anyway. My 400 is 10.5:1 and never gets hot even in hour long, bumper to bumper traffic.
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