The radiator is the last major component of the cooling system that I will discuss in this series. The remaining items will be of lessor importance along with a final listing of heating diagnoses. Having an understanding of how the radiator works and how to improve it is our goal.

Appearing to be a very simple device the radiator has multiple roles to play in the cooling process. It provides a direct means of expelling heat from the coolant, provides a reservoir to hold coolant, and allows a space for hot coolant to expand. The heat carried by the coolant has had many opportunities to dissipate it's self by conduction through the block and heads, but these are not capable of completing the cooling process. The radiator is the last component for heat dissipation before the coolant returns to the engine.

The examples I am using here are for the 62-67 small block radiators, many similarities apply to the big block cars. Radiators are constructed of several parts; both of the tanks are made of .02 thick brass, .03 thickness for the inlet/outlet castings. The castings are thicker to resist damage by over tightened hose clamps and twisting during installation of hoses. Core tubes are approximately .007 thick and the fins are .003 copper/brass. Side rails (mounting brackets) are made of mild steel. Tanks, castings, and brackets are die stamped from flat sheet material. Holes are punched for the inlet/outlet, transmission cooler, drain cock, and filler neck. Looking at the tanks you will notice that they are formed with ridges or ribs in them, adding structural stiffness to prevent ballooning under pressure. The ballooning of a radiator is the number one reason for radiator failure. The factory pressure specification for the filler cap is the maximum pressure your radiator is designed to operate at, over pressurizing will cause a failure. In no case should a higher rate cap be used on a stock radiator.

Radiators have changed very little in function and design since the first automobiles used liquid cooling instead of air cooling. The major differences occurred along two lines of change. In earlier models improvements to the down flow radiator were made to increase efficiency as engines grew more powerful. The cross flow radiators in Fairlanes were introduced to reduce over all height, providing for more streamlined frontal body shapes. Our cars have both types of radiators, the early cars have down flow type, after 1967 the cross flow became the standard design. There is no difference in cooling ability from down flow to cross flow design, they cool equally well.

When a down flow radiator becomes excessively wide it has a difficult time distributing coolant across its entire width with out a helping hand. This help comes in the way the inlet/outlet connections are arranged on the radiator. Hose connections should be diagonal on the radiator inlet on one side while the outlet is on the other side. If this is not possible, the next best arraignment is to have the top connection in the center and the lower connection on either side.

The 62-67 Fairlane V-8 radiator is the least desirable design with both the inlet and outlet connections on the right side. While coolant is passing through this type core it favors the right side of the radiator, the tubes on this side being the easiest route to the lower hose. As a radiator becomes older and more prone to clogging the furthest tubes to the left will plug with debris first and progressively clogging each tube while moving to the right over time. Since the radiator cap on early Fairlanes is located to the extreme left side, by looking into the filler neck with the engine running, there should be considerable coolant flow passing by the opening. If there is very little apparent flow then it can be assume that the left side of the radiator may be plugged. Radiators with the filler neck in the middle or on the same side as the upper hose connection will not give a true indication of total flow; this method is not reliable in that case. Verifying this is accomplished by shutting down an engine that is at full operating temperature and feeling the radiator core for the presents of uniform heat at a given level across the entire width of the core. Coolant temperatures should be highest at the top of the radiator and progressively become cooler as it goes downward. The core will exhibit cold or cooler temperatures in areas where coolant is not flowing. When this plugging is present over heating will eventually become a problem.

The top tank is constructed with a horizontal splash shield or baffle, dividing it into approximately equal chambers, the propose being to prevent sudden discharge of hot coolant. This may occur if the cap is removed while pressure is in the system or while attempting to fill a hot engine. Most after market radiators will not have the baffle in them, obviously as a cost cutting measure. If you are rebuilding your Ford radiator ask that the baffle be reinstalled. With out an air space to expand into coolant pressure will lift the cap and vent coolant out on the road. If an engine becomes over heated, even more coolant will be vented overboard. Without replenishment the coolant can deplete to the point of being unable to supply the engines cooling needs. This is the reason coolant level checks should be made more often on the cars with vent tube systems. Hot weather or high engine loads will require more frequent coolant checks. This is considered normal maintenance. Cars with performance engines will require more attention. Wanting to be more environmentally friendly and stop the dumping of antifreeze coolant onto our streets and highways, Ford started using the recovery/expansion tanks, first on the big block cars and later all engines.

The volume of coolant available at the top tank should always exceed the capability of flow through the radiator core. Keeping the tops of the core tubes covered to give all tubes a chance to cool, the top tank distributes the coolant over the width of the radiator core. The number and size of the tubes in the core dictate the volume of coolant flow.

The lower tank collects the cooled liquid and provides a constant supply to the water pump. In the lower tank (on cross flow radiators the tank with the lower hose is referred to as the lower tank) if equipped with automatic transmission is located a transmission fluid cooler. Earlier Ford automatic transmissions were air cooled, this radiator cooler feature started in about 1957. There are a couple of common internal type coolers. Ford used exclusively the concentric type. It resembles a brass tube with a smaller tube inside; the ends are brazed shut and fittings attached at each end to allow transmission fluid to flow in one side and out the other, while coolant circulates around and through the cooler.

When hot coolant enters the top tank of the radiator, it passes through the core tubes, being exposed to air passing around the fins and tubes. A properly working radiator will only affect about a 50* temperature differential from top to bottom. If the coolant temperature entering the top of the radiator is 185* a good radiator can lower the coolant temperature returning to the engine to 135*. In no case, when a properly working thermostat is used, does the coolant become totally cold (ambient) before returning to the engine. If this were not the case thermal shock could crack the block or heads.

The way to proper cooling is to have more and smaller tubes in a core. This is only limited by the physical size of the radiator. Your radiator must fit into the restrictions of the front of your car, core support opening, fan clearance, and under hood height..

The early Fairlane and many other Ford cars are restricted to the 2-row factory type radiator core because of the very narrow lower tank; it measures only 1 5/8" wide. Fabricating a new lower tank was the only option available to radiator shops in order to install a 3-row core and few shops seem to want to do that.

Stock radiators have had marginal capability except for the original 289 HiPo cars that were 3-row equip. The HiPo had a 2" wide lower tank but they were about as plentiful as "frog hair", until recently. Through the efforts of a dedicated member of The Fairlane Club of America, who contacted Jackson Industries and had this lower tank reproduced. It is made in two styles, for stick and automatic transmissions. The part number for the manual tank is 834079, for automatic 834080. The price runs about $26.00 including shipping. To order have your radiator shop call Jackson Industries at 1-319-652-6881 and ask for the part number you need, as these pieces are not in the Jackson Tank Catalog and are only available C.O.D. from the manufacturer.

How could a radiator become more efficient? By increasing the number of tubes, this will usually require reducing their size to fit more into a given space.

An example would be a 64 Fairlane radiator that has a core size of, 17 1/4" height, x 20 1/4" width, x 1 1/4" thick, 2- row. It uses 1/2" tubes spaced 1/2" on center for a count of 81 tubes. This gives a total of about 1400 sq.in. of tube surface exposed to the air. Using the same measurements and a 2- row high efficiency core, constructed of 3/8" tubes 3/8" on center and no other changes, the surface area becomes about 1360 sq.in. in contact with the air. That is a 3% reduction in tube surface exposed to the air and appears to be going in the wrong direction to gain cooling efficiency. With no other changes having taken place in the physical core size, the core thickness has been reduced from 1 1/4" to 1 inch. I mention this to show that a high efficiency core only gives up 3% surface area while reducing it's thickness by 20%. You are asking what we gain with this smaller tube and the answer is not much, other than slowing the flow, until we make one more change, in the number of fins used.

How the radiator rids the coolant of heat relates directly to the fin count (fins per inch or fpi) of the core. The stock Ford Fairlane 2-row use 12 fpi, this is 10,479 sq.in. of fin surface. With a high efficiency core having 14 fpi the surface area the number increases to 12,679 sq.in. The more fin area exposed to air flow the better the cooling, unless the fin count becomes so dense that air flow becomes restricted. That is just over a 20% increase in fin area. That gives us a 17% total increase in surface to the air, with a 1/4" thinner core.

If you are wondering where this is heading the whole process is to improve your radiator without changing its physical size. If it were carried one step further you would replace your 2-row core with a 3-row high efficiency 14 fpi core. The result would be as follows:

3-row high efficiency verses 2-row stock core

1 1/2" thick core verses 1 1/4" core

14 fpi verses 12 fpi

3/8" tubes (157) verses 1/2" tubes (81)

28527 in.sq. of fin surface verses 10479 in.sq.

The 3 row core has doubled the amount of tubes, tripled the fin surface area, for a result of roughly the equivalent of adding a second radiator in the same mounting space.

Cooling efficiency is not directly proportional to these increases, but should be improved by about 95%.

When I am ask what type core will help their cooling problems many seem to think that a 3-row will not be enough. Unless you are using a big block with a lot of muscle the 3-row is the way to go. There is always the 4-row core for even larger gains and the fin count can be increased further to 16 fpi. My 427 uses a 5-row cross flow radiator with 16 fpi, now that's a real cooler. The reason for using the cross flow was to gain greater frontal opening.

Improvements in cooling can be made by doing some modifications relating to directing more air through the radiator. I have discussed fan shroud and fan blade benefits, another area for improvement is the frontal opening restrictions on the early Fairlanes. With the opening in the core support being 20 1/4" wide it can be enlarged to 21 3/4" by cutting out the sheet metal on each side. This modification alone will increase core frontal opening by 13%. Notching the front strut arm mounting brace where the lower core support meets the inner frame rail will permit the installation of a larger cross flow radiator. The reason for using the cross flow style radiator is because no more increases in size can be gained by height but we can go outward.

Fin count should not exceed 16 fpi. Core thickness should not be more than 5-rows of tubes; these will cause stagnation, as air flow will not be able to penetrate such a tight core. In everyday use high fin count radiators (aluminum) will clog with dirt and debris, further reducing their cooling capability. This is but one of the disadvantages associated with aluminum radiators, being not as efficient as cooper/brass, many require over 20 fpi. these ultra high fin counts are used to make up for their lesser cooling ability.

To reiterate Copper/brass material cools better than aluminum, fact. Many aluminum radiator manufacturers claim otherwise, but unless compared pound for pound copper/brass is the better heat conductor. If a few ounces of weight is critical chose the aluminum, but best cooling is cooper/brass.

Pluses and minuses of radiator construction materials:

Aluminum Copper/Brass

Metal oxidizes (Yes) = Same (Yes) =

Welded construction (Yes) + Solder construction (No) -

Readily repairable (No) - (Yes) +

Rebuildable (No) - (Yes) +

Epoxy resin header to tube (Yes) - (No) +

Better heat conduction (No) - (Yes) +

Weight advantage (Yes)+ (No) -

Has stock appearance (No) - (Yes) +

Looking at the differences in radiator construction materials we see some very big dissimilarity between the two most common types.

Most common metals are subject to oxidation in some form. Aluminum being a soft metal must have a surface conditioning to protect it from acids and salts. Anodizing is the method used, contrary to belief it is not a coating applied to the surface of the aluminum, but a molecular treatment of the surface to protect it. If the surface were chipped or cracked it will expose bare metal. Bare aluminum is very hard to keep from oxidizing. If you have ever tried to keep a set of custom wheels shining after they have had clear coat damage, you know that they require cleaning every week. If the oxides develop under the clear coat it’s a waste of time without stripping off the clear coat. Aluminum radiators that become nicked by sand or road debris will immediately start to oxidize eventually causing a leak.

Copper/ brass radiators are subject to oxidation also, but are a much more forgiving metal that resist road salt and acid rain even with out any special surface preparation. Acidic coolant can attack the solder joints, oxidized solder is similar in effect as rust is to steel, it no longer is a viable metal and has lost it's strength and bond capabilities. Solder joints can be restored to like new by a repair procedure. Copper/brass is a much harder metal and even if the surface is damaged, it is the same material all the way through. Radiators are lightly painted black for a reason, it radiates heat better. Aluminum radiators are almost never painted because it reduces their cooling ability.

Aluminum radiators are welded together heliarc type welding is used to join the aluminum pieces. This would seem to be a very desirable way to build a radiator, not having weak joints, and a much more ridged construction. The problem is that if this radiator needs repaired, fix a leak, repair a crack, or remove a tank to restore full flow by rodding the core, it is almost impossible to do so. Some aluminum radiator are so poorly welded where the tubes meet the header that the manufacturer has applied an epoxy sealer as an after thought to prevent built in leaks. This epoxy sealer is another area that is not readily repaired. These leaks are built in from the factory and will appear when the radiator gets a few years old and had many heat cycles. The sealer becomes hard, cracks, peals up and the leaks will come from underneath.

Copper/brass radiators can be unsoldered at any joint and have replacement parts or repairs done readily. If your aluminum radiator has a problem on a trip try to find an aluminum welder willing to attempt a repair.

If stock appearance is your goal then the original copper/brass radiator is the way to go. Most every part for even the earliest radiator models is available to repair or fabricate any radiator. The silver gray look of the aluminum radiator is very eye catching, signifying that a modification has been made, while copper/brass radiators are harder to detect custom work, other than polishing the tanks.

Rebuilding of aluminum radiators is not an option, because of cost and no parts are available. Most aluminum radiators will be discarded and replaced with a new one when problems develop, while copper/brass radiators are able to be rebuilt, modified, or fabricated from scratch to fit any need.

If the very latest advances in radiator technology are what you are looking for, the check out: The Brass Works <www.thebrassworks.net> ,their "Heat Sponge Radiator" blows away all the competition, the efficiency numbers are fantastic.

The comparisons show advantages as well as disadvantages for both types of material, the choice is yours.

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