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Discussion Starter · #1 ·
I know this has been covered before and I have read the archives, but yet I am experiencing what I believe to be higher than normal operating temps on my 396. even @ a cool (south Florida) 65o, my 396 runs from 200 to 220 degrees. I have brand new "nice" everything in the cooling system including a three core radiator (stock). I've replaced or tried everything twice so I know it's not a "parts" problem. No blown head gasket either. Is this normal? what temps does anyone else out there see @ 65 degrees? Would a 4 core radiator help? I'm really concerned because come summer I'll see 95 degrees plus the AC will be on!
 

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I take it you have confirmed the temp guage is correct, and the engine is tuned correctly.

A rundown of the things needed for 180 degree operation in your climate:

Your radiator is fine for the job.

Use a Mr. Gasket (Robertshaw) pressure balanced thermostat, 180 degrees, and is a must with a Flow-Cooler type pump setup to stop the closing action of the water flow from the higher volume from the better pump. Still the best thermostat to run with any system design.

A Flow-Cooler type water pump would be a good addition, and you can make a stock pump into one by removing the pump back plate, and adding a full .035 steel plate to the water pump impeller fins. I weld the fin edges to the home-made plate, instead of pop-rivetting it, as Flow-Cooler does. If you rivet the plate onto the fins, use stainless steel rivets.

Anti-freeze to water ratio should be 30 percent anti-freeze/70 percent tap water, no special additives are needed. 30 percent anti-freeze is quite sufficient for the area you are in for complete protection. Don't use any de-mineralized or special waters, they are so mineral starved, they will eat any mineral in sight, iron, aluminum, etc. 50/50 mix doesn't transfer heat as efficiently as the 30/70 does, and the protection level is actually only 10 degrees different between them.

Full shroud for the radiator, covering all the fin and tube area so the fan can pull air through the entier radiator air flow area.

Either a direct mount flex fan, or an air conditioning clutched full fan, half in the shroud, half out. No electric fans, they don't work on early engines made to run at 180 degrees or cooler.

NO UNDERDRIVE PULLEYS ON THE CRANK OR WATER PUMP. I see more cooling systems that don't work trying to save a horsepower from this one wrong thing. Underdrive pulleys are for engines that are designed to run at 220 or more degrees, ead EMISSIONS engines, and yours isn't one of them.

First, though, you should make sure the timing and ignition curves are correct, and a workable vacuum advance is in place if there is enough engine vacuum to support it, and the carburetor should be jetted correctly for the engine, and the exhaust system is OK.

All these things can contribute to excessive heating for any engine.

I set my engines up this way, and to the last one, I have complete thermostat control of the engine temp, even when I lived in a small town in central California, where the temps got to 118/119/F in the summer.

Just what I have found to work over the last 30 years of messing with engines and my own big blocks (I have a few).
 

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Discussion Starter · #4 ·
Here's how I'm set up:
New Modine 3 core radiator
Flow-Cooler water pump
Mr Gasket hi-flow 180 thermostat
stock pulleys (I think)
fresh anti-freeze/water mixture
stock fan shroud
new clutch fan with factory blade
engine set up CORRECTLY; timing, plugs;jetting etc.

I don't think it's a parts problem. Now I'd like to know what is the correct crank and water pump pulley diameters supposed to be? That's the only thing I'm not sure about.

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I am in SW Florida and I found the fan itself makes the biggest difference. I stuck a flex fan on and could hardly make it through a long stop light without overheating. I thought the orginal shroud hurt the underhood appearance so I had a custom polished stailess shroud made, it looks great and I haven't seen 190 degrees since. Best $150 bucks I have spent on the car.

Pat 70 SS 402
 

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I have always put 4-row radiators in and never had a problem. I used to have to turn the heater on to cool off the motor about 5-15 degrees or it would hold steady. The heater core is your other radiator even though it got a little warm inside the car I was happy that the Super Chevy traffic jam did not kill my motor. I put a 4-row in my 69 SS with a 454 and had to put a 180 stat in because it would not get above the cold mark on the guage. Engine timing can affect the temp also.

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Malibu 307 (aka 406 smblk)
69 SS 396(aka 454)
Wolf in sheeps skin
 

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I have a .060 402 11.1 pistons and mine runs
at 180...I had a flex fan on it and the temp would go up riding down the highway,put on a
clutch fan problem fixed.Where are you getting the temp from...manifold or head.
I also have a 4 core radiator,which also helps.

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Vendo396
http://www.ultranet.com/~vendo
 

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4 core rad , stock pump 160* thermo .currently 100% water...i run 180* now but was getting hot (to 220 then i would shut her down or get out of traffic) during hot fla summer

am going to afco alum rad this spring

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Rich
Cocoa Beach, Fla
Team Chevelle #380
[email protected]
www.chevelles.com/showroom/70_SS_454.jpg
 

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Try this:

Start with a cold engine.
Take the radiator cap off
Start the motor
Stick an instant read thermometer in the radiator neck
Let it warm up
Check the thermometer against your guage.

I bet the guage is off. Try this before spending any $$$.

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Dale P.
Team Chevelle Member# 423
65 El Camino
72 Monte Carlo
"..you did you take the washer off, right?"
 

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I was having what I thought was a heating problem also. Went to my trusty mechanic and he walks up with a laser gun that reads heat wherever it is pointed and trigger pulled. It was facinating to watch, heads, intake, other parts of the block running at about 180 then put on exhaust manifold and it was over 400 (as it should be). My gauge was off so we replaced sender and it works fine. I am still trying to find the laser gun so I can have it with me at all times.
Mechanic thought he bought it at Home Depot but no luck so far.
 
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