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Discussion Starter #1 (Edited)
Hey all - I was wondering if it is common - normal - expected, that the 1966 SS 327 (not L-79) usually overheats?

Even when it is relatively cool, it overheats and the temp shows above 220F. It does fine for short drives, but if I am driving through town when the temps are over 80 and come to a stop light - sitting with it idling will cause it to overheat and die.

My other 2 Novas and even my 31 Chevrolet (which others say is common to overheat) does fine until the temps are above 110.

I have changed out the heater core and had the radiator cleaned. It helped and now I can go 50 miles before it dies instead of the previous 30 miles. :D
 

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It shouldn't be overheating. Flow is what cools your engine, both on the water side and the air side. Increasing the water flow also increases the turbulence, which is another contributor to heat transfer.
 

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Mine was overheating years ago with the original radiator in it. I had planned an upgrade anyway and I figured it was shot so went with the relatively inexpensive Summit brand aluminum and added an electric fan. After that I would maybe hit 200 sitting in traffic on a hot day but right back to 190 as soon as I got moving. As Mike said it's not normal. If it overheats and dies at a light something's not right.
 

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What do you have moving air through the radiator? Stock clutch fan, solid fan, electric fan, etc? Any shroud on the radiator? What thermostat is in it?
 

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Discussion Starter #6
What do you have moving air through the radiator? Stock clutch fan, solid fan, electric fan, etc? Any shroud on the radiator? What thermostat is in it?
  1. When I was a kid, I always heard my dad talk about what he did (he was the original owner of the car) - changed the radiator to a "heavy duty" one. (Not sure what exactly that meant).
    1. He mentioned that he put in an overflow tank.
    2. He put in a bigger water pump
    3. He put in a 6 blade fan to replace the stock 4 blade.

    It is not an electric fan, and no shroud on the radiator. The thermostat is 195.

    So for the most part, it is pretty close to stock. But it has always overheated.

    It shouldn't be overheating. Flow is what cools your engine, both on the water side and the air side. Increasing the water flow also increases the turbulence, which is another contributor to heat transfer.
    Ok, so if it SHOULDN'T be overheating - the question is why? Or what to do about it (without a lot of mods because I would like to keep it as close to stock or origonal as possible. Since it was the way my dad kept it since the day he bought it new).
 

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Since you want the car to look generally original, here's what I would do:
1. Flush the cooling system with a chemical cleaner and fresh water, then completely drain the system and add new coolant.
2. Put in a 180 degree thermostat
3. Buy a reproduction "L79" fan shroud (this is something that could have been a 'Day 2' addition from the dealer in a hot climate).
4. Be sure your 6-blade fan fits in the shroud. It should sit just inside the lip of the shroud. If it doesn't you'd need to add either an aluminum spacer between the fan and the water pump and/or a '67 style radiator spacer that moves the core back away from the radiator support. (Again, parts that might have been added by a dealer to a new car that overheated.)

If it's still overheating, I'd say that the problem is the actual coolant flow. As noted above, the radiator could be (a) clogged or (b) still too 'small' [too few rows of coils] or the engine block could have a gasket issue. If you've reached this point, I'd remove the radiator and take it to a reputable radiator shop for a professional cleaning.
 

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Discussion Starter #8
Since you want the car to look generally original, here's what I would do:
1. Flush the cooling system with a chemical cleaner and fresh water, then completely drain the system and add new coolant.
2. Put in a 180 degree thermostat
3. Buy a reproduction "L79" fan shroud (this is something that could have been a 'Day 2' addition from the dealer in a hot climate).
4. Be sure your 6-blade fan fits in the shroud. It should sit just inside the lip of the shroud. If it doesn't you'd need to add either an aluminum spacer between the fan and the water pump and/or a '67 style radiator spacer that moves the core back away from the radiator support. (Again, parts that might have been added by a dealer to a new car that overheated.)

If it's still overheating, I'd say that the problem is the actual coolant flow. As noted above, the radiator could be (a) clogged or (b) still too 'small' [too few rows of coils] or the engine block could have a gasket issue. If you've reached this point, I'd remove the radiator and take it to a reputable radiator shop for a professional cleaning.
Thanks for your suggestions. This helps. I did mention in the original post that I have had the radiator shop clean and rebuild the radiator. It was flushed when I started this project cuz it had been sitting in my moms garage for about 15 years not running. When I got it running this past spring, it did not run any hotter than it has for the last 50 years when I was a little tyke, so I did not think sitting caused any change other than to make sure it was flushed and cleaned good. So I will try the thermostat and the shroud.
 

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Thanks for your suggestions. This helps. I did mention in the original post that I have had the radiator shop clean and rebuild the radiator. It was flushed when I started this project cuz it had been sitting in my moms garage for about 15 years not running. When I got it running this past spring, it did not run any hotter than it has for the last 50 years when I was a little tyke, so I did not think sitting caused any change other than to make sure it was flushed and cleaned good. So I will try the thermostat and the shroud.
Shroud, shroud, shroud. I fought these issues on my 67. After replacing/ upgrading every component of the cooling system, I bought a repro shroud from one of the nova vendors and all my problems went away. I actually had to put a warmer stat in the car after adding the shroud because it was running too cold. Make sure your fan is 1/2 to 3/4” behind the shroud. Also make sure the shroud is tight to the radiator.
 

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Only bring this up because it happen to me. GM 350/290 HP seven blade clutch fan with fan shroud and 4 row brass rad.,would overheat during slow driving (parades) or run hot on long drives in 90 degree weather. Turns out fan pulley was bigger than the crankshaft pulley, so the fan was under driven. I replaced the fan pulley with a smaller one and no more overheating or running hot issues. The fan is over driven now and it pulleys in a ton of air. You might have other issues, but thought I would mention my solution to the overheating in my case. Also, do not ever remember overheating issues when I was in high school running a '57 belair, 283 and later a 327 no shrouds, fixed fan, no thermostats, and water only (no antifreeze). Street racing all the time and never an overheating problem.
 

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Discussion Starter #13
Only bring this up because it happen to me. GM 350/290 HP seven blade clutch fan with fan shroud and 4 row brass rad.,would overheat during slow driving (parades) or run hot on long drives in 90 degree weather. Turns out fan pulley was bigger than the crankshaft pulley, so the fan was under driven. I replaced the fan pulley with a smaller one and no more overheating or running hot issues. The fan is over driven now and it pulleys in a ton of air. You might have other issues, but thought I would mention my solution to the overheating in my case. Also, do not ever remember overheating issues when I was in high school running a '57 belair, 283 and later a 327 no shrouds, fixed fan, no thermostats, and water only (no antifreeze). Street racing all the time and never an overheating problem.
That is a good point. The fan I have is a 6 blade oversize. I will definitely check into getting a smaller pulley.
 

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Turns out fan pulley was bigger than the crankshaft pulley, so the fan was under driven.
That is a good point. The fan I have is a 6 blade oversize. I will definitely check into getting a smaller pulley.
This pulley also drives the water pump so the effect is more flow from the pump as well.
 

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My 2 cents, Shroud, especially here in AZ. 160 0r 180 degree thermostat of good quality, ie; Milodon, Hypertech, etc., check function b4 installing. Think about a Quality Water Pump, Like; Edelbrock, Milodon etc., and possibly a new radiator. Call or text me with any questions.:yes:
 

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fought same problem, Got were I wouldn't drive car, Junior from chevy2only suggested there L79 repop radiator, problem solved
 

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Just like some of the previous posters have said.

Its got to have a Shroud. I have built multiple configurations of drive trains over the years, BB, SB, High horse, low horse, etc... It comes down to one thing, heat transfer, and you can't transfer heat if you aren't moving air thru the radiator. Think about is this way. Think about air as fluid. We have always heard the saying "water will always take the path of least resistance". Well what is easier for air to do, just recirculate itself within the engine compartment or be pulled thru the radiator? The shroud will make a huge difference.
 

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Discussion Starter #19
Ok, spouse listened to me and I got my Christmas wish. A new shroud.

Classic industries https://www.classicindustries.com/product/1966/chevrolet/chevyiinova/parts/3878892.html

Now, the radiator attaches with "L" brackets as shown in the drawing (UPC 11-13, page A9) of the assembly manual. What I need to know now, is how do I attach the thing to the radiator? I am puzzled by the hardware that I find online looking for answers. I thought maybe UPC V-01 might tell me something. It doesn't look like the radiator attaches the same way, and looks like this is NOT the "L" bracket attachment from the first UPC. It looks like it is a "C" type channel on the vertical sides that the radiator is supported by in V-01.

There are no holes in the thing, and in searching for Chevrolet Nova attachment hardware, I find anything from

clips
https://bit.ly/2GQNRvQ
to only bolts and speed-nuts
https://bit.ly/2RgZhNC
to "C" brackets
https://bit.ly/2rTUdk5
to straight supports
https://bit.ly/2ERimA1
to nuts and zip-ties
https://bit.ly/2Q7zpiM

I did see something that looked like it had long bolts and rubber-looking or poly-looking spacers about 1 inch in length - but in my searching..... I can't find that webpage again.

Help????? (Photos, an installation manual, and part numbers would be best).
 
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