Shroud Your Rad for an Ice-cold Hudson!
Note: This mod requires the 1970s Dodge truck/van radiator conversion, and has not been tested with stock Hudson radiators. The Dodge radiator is a popular mod, and offers better cooling capacity than stock. If it could keep a big V8 cool, it can keep a big straight-six cool too! This mod also uses the stock Hudson mechanical water pump fan.
Hudsons, like many early post-war cars suffer from poor engine cooling, especially in "parade" traffic. In our opinion, this mostly boils down to the lack of a fan shroud. But not this one! I like to drive this car, and our Virginia summers are HOT, so Dad (DavidC) and I did this modification to be able to drive this car in all weather. I've been in traffic jams in my car in upwards of 95℉ and 90% humidity. While I have experienced vapor lock under these conditions, I've never once overheated my old engine.
The Final Product
Here are some snapshots of the shroud when installed.
The shroud kit we used is PN Z40026 by HR Performance. Some other manufacturers sell this kit as well. The dimensions we used are 18-1/8" x 28-1/8" x 2-1/2". It generally looks like this, and is broken up into a large, rectangular shroud and a circular ring for the fan shroud/guard. It typically comes with a variety of fasteners and tabs to mount it to the radiator mounting brackets or the upper radiator supports.
Kit Modification Tips
The kit requires some modification to get it to work in this application. First, the height has to be shortened to match the height of the Dodge rad. In doing this, we preserved the geometry by cutting out and raising the lower trapezoid of the body and pop-riveted it higher in the shroud. We then cut off the excess shroud body.
Second, we decreased the overall depth of the rectangular shroud body. We did this pretty drastically, about an inch, to allow for an AC condenser in front of the Dodge rad. The depth is only important to getting the circular shroud ring completely around the fan blades without the fan sticking too far forward into the rectangular body of the shroud, or so far out that it's completely outside of the shroud. See the picture below for a good idea of the shroud depth in relation to fan insertion. To make sure the fan blades were absolutely where we wanted them to be, we added a fan spacer on the water pump pulley.
Finally, we relieved the quarter-circle of the ring that gets close to our AC compressor (where the factory generator is located). See below picture for an idea of this relief. Most of all, it makes it easier to remove the AC compressor without removing the shroud, if the need should arise.
We mounted the circular fan guard higher than the rectangular shroud body, almost in line with the rad filler neck (you can see this in the above picture). This is because the Dodge rad sits lower than the stock Hudson fan, and we wanted to keep the original mechanical fan. This meant using additional aluminum material (either included in the kit or leftovers) as a front to the circular ring where it protrudes above the rectangular body. This piece was cut into a semicircle and pop-riveted to the front of the circular ring.
We used varying lengths of U-shaped rubber channel to protect the rad from sharp/hard aluminum edges, since the shroud mounts directly up against the fins of the rad. We also used this material in between pieces of folded aluminum at the bottom of the shroud.
The shroud is fastened to the radiator support mounts with the included fasteners and small aluminum tangs. We later removed the shroud entirely and brought it to a local welder who works with aluminum. They welded all of the open joints and replaced all of the pop-rivets with beautiful welded beads. They also ground off and filled in the rivets. This made the shroud look much more professional.
Note on choice of stock, mechanical fan vs aftermarket, electrical fans: we have found the stock mechanical fan performs more than adequately. With this shroud, the flow is excellent, and will vacuum a shop towel up against the grill of the car while idling. It is less noisy than an electrical fan, and looks nicer than plastic electric "pusher" style fans that some folks put in front of their rad.
Results, Additional Info
The proof is in the increased usability and drivability of the car. The cooling performance is fantastic. The coolant temperature has rarely passed 210℉, even just idling in traffic. I have never belched coolant from the overflow or been stranded on the side of the road as a result of overheating.
A note on our coolant mixture. Our coolant is primarily 50/50 ethylene glycol. We also mix in a bottle of RedLine Water Wetter and some water-soluble oil. We got this from one of Walt Mordenti's tech tips, and we owe him a great deal for the drivability and performance of this Hudson.