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Hello, a month ago I bought a 64 impala 425hp 409 car. I’ve noticed that in the few short runs ( 20 miles or less) I have made with it that the coolant temp is running at 210 degrees. This car has an electric cooling fan with a shroud that covers the radiator except about 3/4” on either side of it . It runs great. Is this too hot for this engine to run?
 

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Yes. If it were my car, I would go back to an original type Clutch Fan and original type Fan Shroud, although, always start with the simple things first. I would put in a new Thermostat, flush the Cooling System and re-fill with 50-50 mixture of new Coolant. Also make sure that your Radiator is large enough as well as making sure you have the correct Water Pump on there.

For further assistance, check with the boys over at the 348-409 site:

 

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Hello, a month ago I bought a 64 impala 425hp 409 car. I’ve noticed that in the few short runs ( 20 miles or less) I have made with it that the coolant temp is running at 210 degrees. This car has an electric cooling fan with a shroud that covers the radiator except about 3/4” on either side of it . It runs great. Is this too hot for this engine to run?
Depends. 210F while moving at forward speed (25 mph, or so) would be hotter than I would want. The cooling system in that 'mode' should maintain the thermostat opening temp (within about 5 %). Sitting at idle or stuck in traffic? Within about 10%.

A 50/50 mix at 15 psi does not boil until about 240F. The 'idiot light' does not start to illuminate until around 235F. 210F is not 'critical' but I would try to bring it down some.

Advancing initial timing (if your engine it not already at 'best') reduces temps some.

I too, prefer the GM OEM cooling system design. Electric can be made to work but relying on the GM engineered system is proven and less risky.

Pete
 

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I just wanted to add that 2 other items can cause higher temps in addition to what they've already mentioned above.
1. Make sure the fan is turning the proper direction. I'm completely serious, I've heard about some hooking them up incorrectly or they buy a 'pusher' instead of a 'puller', mount it incorrectly, etc.
2. I'm not sure what carburetor you have on there, and I'm guessing it's history is a bit unknown,...so it would be good to check the plugs and 'read' them. See if they are still mostly white porcelain or have a nice coating on them. Looking for lean conditions, or confirmation of proper jetting and A/F ratio.
 

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63 imp. 283. PG. 321 rear
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Yes. If it were my car, I would go back to an original type Clutch Fan and original type Fan Shroud, although, always start with the simple things first. I would put in a new Thermostat, flush the Cooling System and re-fill with 50-50 mixture of new Coolant. Also make sure that your Radiator is large enough as well as making sure you have the correct Water Pump on there.

For further assistance, check with the boys over at the 348-409 site:

Just saying check all connections for any leak and replace worn hoses and clamps. Check overflow at radiator cap for a little leakage. Check that you maintain full fluid level of course, goes without saying, good luck. 👍🏼
 

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1961 Impala 2 Door Sedan
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When I did the research before I thought 200-215 was the "ideal" temperature range from the factory. Best combination of efficiency, power, keeping everything clean, etc. Did they run cooler thermostats on the performance variants to help with preignition?

My 283 is very happy running at 210. I have a 348 to build and was planning on keeping the OEM thermostat temperature since it will be a very mild build.
 

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I just wanted to add that 2 other items can cause higher temps in addition to what they've already mentioned above.
1. Make sure the fan is turning the proper direction. I'm completely serious, I've heard about some hooking them up incorrectly or they buy a 'pusher' instead of a 'puller', mount it incorrectly, etc.
2. I'm not sure what carburetor you have on there, and I'm guessing it's history is a bit unknown,...so it would be good to check the plugs and 'read' them. See if they are still mostly white porcelain or have a nice coating on them. Looking for lean conditions, or confirmation of proper jetting and A/F ratio.

I thought the difference between push/pull was just polarity?
 

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Agreed it could very well be just that, but depending on totality of what the part is, like a possible enclosed shroud I have heard of those that dont know better mounting a puller in front but not changing the polarity.

Either way - as long as you're aware and know what you're looking for.....all the better. (y)(y)
 

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Agreed it could very well be just that, but depending on totality of what the part is, like a possible enclosed shroud I have heard of those that dont know better mounting a puller in front but not changing the polarity.

Either way - as long as you're aware and know what you're looking for.....all the better. (y)(y)
I was asking for clarification as well to make sure I had my facts straight and another thing for OP to check.
 

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I appreciate all of your feedback, I have ordered a factory style fan shroud and fan and fan clutch for it. Also going to install a 180 degree thermostat for it. Will update you on the result
The fan clutch is a very clever devise that de-clutches the fan when the it is not needed for cooling (and at higher rpm). That allows the engine torque used to rotate the fan to be applied to other purposes (propulsion). It is a VERY useful devise ( and is worth its cost) but it does not 'enhance' cooling.

Did you check your ignition timing?

Pete
 
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