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.
