Radiator cap and thermostat suggestions? (283) - Impala Tech
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post #1 of 7 (permalink) Old 04-19-2015, 12:21 PM Thread Starter
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Radiator cap and thermostat suggestions? (283)

The car 1966 impala bone stock 283 2bl AT FACT AC

I just ordered a radiator and I honestly don't know which to use a 160 or 180 thermostat, or a 13 vs 16 radiator cap. I live in north Florida where it is very humid and hot all the time if that makes a difference which I'm sure it does. The car is rarely driven and when it is driven I just cruise. Not that this 283 will do much else lol. I'm not going to drop in the radiator til Tuesday so I have some time to make up my mind, I would love to hear suggestions on what you guys use and why.

Btw I noticed when I was looking at my radiator to verify a good fit for my replacement that the fan is about 5 inches away from the radiator. Shouldn't it be an inch or two closer?
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post #2 of 7 (permalink) Old 04-19-2015, 04:19 PM
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Ethan the higher the pressure on the cap the higher the coolant temperature in the block can be before it boils. Once it boils it stops being a coolant, and as you know from watching a pan of water boil the bubbles form on the surface of the pan first.

Those bubbles act as an insulating blanket that means the heat is prevented from moving past that barrier so you can get hot spots in the engine that can promote deadly detonation. Detonation is the auto-ignition of the fuel because the temp exceeds the octane rating of the fuel. You hear it as pinging or a rattle in the engine. Detonation breaks your stock cast pistons apart (which is why race engines are built with forged pistons; which are not stronger than cast pistons, they just stay in one piece when they die).

The stock pressure cap rating was 16-18 pounds of pressure. The 13 is offered because in an old car the radiator AND the heater core are soldered together. That soldered joint is weak. Put too much pressure on an old solder joint and you have a coolant puddle on your passenger side carpets, or an over heated engine as all of the coolant is pushed out past the joint that failed.

Aluminum radiators used in modern cars and race cars are not being used because aluminum is a better conductor of heat, it isn't. The factory uses an aluminum radiator in modern cars because aluminum is today cheaper than copper is to buy (because we have already retrieved all of the easily available copper on the planet). Racers use aluminum radiators because they are welded together not soldered. That makes them stronger: as such, they can increase the pressure on the coolant by way of using a 24 pound cap. Also because aluminum is stronger the radiator tubes can be made bigger. The tubes are 56% bigger which increases the surface area allowing two one and a quarter inch tubes to cool the engine better than four three eighth inch diameter copper tubes can even though copper is the better conductor of heat.

As to the thermostat, I run a 160 in my big blocks to decrease the temperature of the heat soak in the Otto Cycle. From a Thermodynamics point of view, the higher I can drive the temperature in the combustion chamber by increasing the static compression and limiting the drop in the dynamic compression in cam duration the greater will be the difference in the two extremes which increases the horsepower potential in the thermodynamic cycle. The factory runs a higher temperature thermostat to reduce emissions (modern thermostats are 210 degrees).

Big Dave
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post #3 of 7 (permalink) Old 04-19-2015, 07:06 PM Thread Starter
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Ethan the higher the pressure on the cap the higher the coolant temperature in the block can be before it boils. Once it boils it stops being a coolant, and as you know from watching a pan of water boil the bubbles form on the surface of the pan first.

Those bubbles act as an insulating blanket that means the heat is prevented from moving past that barrier so you can get hot spots in the engine that can promote deadly detonation. Detonation is the auto-ignition of the fuel because the temp exceeds the octane rating of the fuel. You hear it as pinging or a rattle in the engine. Detonation breaks your stock cast pistons apart (which is why race engines are built with forged pistons; which are not stronger than cast pistons, they just stay in one piece when they die).

The stock pressure cap rating was 16-18 pounds of pressure. The 13 is offered because in an old car the radiator AND the heater core are soldered together. That soldered joint is weak. Put too much pressure on an old solder joint and you have a coolant puddle on your passenger side carpets, or an over heated engine as all of the coolant is pushed out past the joint that failed.

Aluminum radiators used in modern cars and race cars are not being used because aluminum is a better conductor of heat, it isn't. The factory uses an aluminum radiator in modern cars because aluminum is today cheaper than copper is to buy (because we have already retrieved all of the easily available copper on the planet). Racers use aluminum radiators because they are welded together not soldered. That makes them stronger: as such, they can increase the pressure on the coolant by way of using a 24 pound cap. Also because aluminum is stronger the radiator tubes can be made bigger. The tubes are 56% bigger which increases the surface area allowing two one and a quarter inch tubes to cool the engine better than four three eighth inch diameter copper tubes can even though copper is the better conductor of heat.

As to the thermostat, I run a 160 in my big blocks to decrease the temperature of the heat soak in the Otto Cycle. From a Thermodynamics point of view, the higher I can drive the temperature in the combustion chamber by increasing the static compression and limiting the drop in the dynamic compression in cam duration the greater will be the difference in the two extremes which increases the horsepower potential in the thermodynamic cycle. The factory runs a higher temperature thermostat to reduce emissions (modern thermostats are 210 degrees).

Big Dave
Maybe I'm not comprehending, your saying that my heatercore is soldered to my radiator? I see a radiator attached to the radiator support, the shroud is attached to the radiator. In front of radiator (or behind depending on how you perceive things) is the AC condenser. The heatercore is located through the firewall behind all that lovely AC junk. I know your very knowledgable and I'm not a mechanic, but I'm just not following what your talking about.
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post #4 of 7 (permalink) Old 04-19-2015, 08:08 PM
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No, the end tanks on both the heater core and the rad are soldered to the tubes/fins.

For your location and application, I would run a stock thermostat and cap.

Two doors, four doors, wagons, and ragtops.
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post #5 of 7 (permalink) Old 04-19-2015, 08:30 PM Thread Starter
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Quote:
Originally Posted by jayoldschool View Post
No, the end tanks on both the heater core and the rad are soldered to the tubes/fins.

For your location and application, I would run a stock thermostat and cap.
There it is! That's what was thinking.

That's the 180 and the 16 right?

I wish the thing had gauges that allowed me to read a temp rather a dummy light but it doesn't. I could buy a set of gauges (which I plan on) but I'm not confident messing with wiring. I've been there done that and the results weren't good lol.

Now the actual placement of the radiator to the fan. The current radiator is about five inches to the radiator. The fan sticks out of the shroud at about 3/4 of an inch. I mean it looks fine but I thought that the fan was to be closer to the radiator. I haven't placed the new one in yet but if the new one ends up being the same or further, should I then put in place spacers to push the radiator closer? My 65 didn't have a fan shroud, but then again it wasn't a AC car. I think the shroud is special to the AC but I don't know if that changes the acceptance in fan to radiator distance because of the shroud.

Lmao this car consumes my life and I have no clue what I'm doing. Thank god Im not affraid to pick up a tool or ask a question.

I appreciate the feedback guys this site is great
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post #6 of 7 (permalink) Old 04-19-2015, 09:30 PM
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Fan partially sticking out of the shroud is ideal. You should see the wind tunnel on a stretched A-body frame in a 1971 Monte Carlo. NASA could put the Shuttle in there for air flow testing.

Big Dave
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post #7 of 7 (permalink) Old 04-19-2015, 09:34 PM Thread Starter
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Quote:
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Fan partially sticking out of the shroud is ideal. You should see the wind tunnel on a stretched A-body frame in a 1971 Monte Carlo. NASA could put the Shuttle in there for air flow testing.

Big Dave
Lol so it's ok then if the fan is further away than a few inches from the actual radiator?
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