Our sheetmetal shroud mounts...
Our sheetmetal shroud mounts a 16-inch SPAL fan. It moves lots of air--If you happen to have your arm hanging out the window when the fan kicks on the heat coming out of the hood louvers can be felt.
Keeping a hot rod cool can be difficult, but the OEM's have shown it can be done even with all they have to contend with, so why not learn from them. Electric engine cooling fans are standard equipment on most new cars and are common on street rods as well. New cars also have shrouds to make those fans more efficient, and most street rods probably should have one if they don't. What we're going to show here is how simple it can be to have both with an easy to fab fan mount and shroud.
In this case the street rod in question is a Flathead powered Model A. As we were having a new Brassworks radiator built, we had them include a fan and shroud while they were at it. Here's how it was done.
Un-shrouding A Shroud
As we expected the Model A's cooling system worked perfectly with the engine temperature always right around 180-degrees even on the hottest days. However, we noticed the fan actually came on more at high speeds than low.
We began to suspect that the shroud was actually restricting airflow above 50 mph, so on a hunch we used a hole saw to put a pair of 3-inch vents below the fan. We planned to put rubber flaps on the holes so at low speed the fan would suck them against the shroud and pull all the air through the radiator--at higher speeds with the fan off the flaps would blow open allowing more air to flow through the shroud.
After cutting the holes in the shroud we found the fan never comes on above 45-50 mph, and at lower speeds the fan runs when necessary and the engine still stays cool without the flaps. Very cool.
Ted Noonkester handled the...
Ted Noonkester handled the construction of the shroud, which was made from 16-gauge galvanized sheetmetal.
The size of the shroud is...
The size of the shroud is determined by the height and width of the core--1-1/2 inches were added to each side to allow for mounting flanges, -inch flanges were added at the top and bottom to seal against the tanks.
After trimming the sheetmetal...
After trimming the sheetmetal to size a file was used to deburr the edges.
Notches were laid out in all...
Notches were laid out in all four corners, they will allow the edges to be folded in a box and pan brake.
Although Ted used a notch...
Although Ted used a notch cutter the corners could be cut by hand.
A box and pan brake has removable...
A box and pan brake has removable fingers than allow for bending edges 90-degress to one another. In this instance the ends were folded first--fingers were added then the longer sides were formed.
Here all four sides of the...
Here all four sides of the shroud have been folded 90-degrees. In some cases it may be necessary to trim the top and bottom flange so they don't rub against the radiator core.
We wanted the biggest fan...
We wanted the biggest fan that would fit, which turned out to be a 16-inch curved blade design with an integral mounting ring and guard. Ted measured the mounting ring of the fan to determine the size of the hole to be cut in the shroud.
In this particular application...
In this particular application the fan had to be mounted as high as possible to allow clearance for the Flathead's front mounted distributor.
After determining the center...
After determining the center of where the fan was to be located, Ted used a compass to lay out the hole to be cut.
A hole saw was used to make...
A hole saw was used to make a starting point for some sharp aircraft shears. Ted's done this a time or two so staying on the layout line wasn't a problem.
With the hole cut and the...
With the hole cut and the edges deburred mounting holes for the fan assembly were drilled.
L-shaped mounting brackets...
L-shaped mounting brackets slip into the frame of the fan and secure the assembly to the shroud with screws and locknuts.
The finished assembly installed...
The finished assembly installed on the radiator. Two sheetmetal screws per side secure the shroud to the radiator's side straps.
Our Flathead is equipped with...
Our Flathead is equipped with 160-degree thermostats, new Brassworks radiator, electric fan with shroud and a pair of Hotronics' fan control switches (on at 190 degrees, off at 170-degrees) wired in parallel (one in each head).