If your Baby Bird still has the original steel air ducts that bring fresh air into the passenger compartment, you may want to remove them to check their condition and restore them as needed. After almost 50 years of use, the snow, salt, silt and mud that was thrown off by the tires has had time to corrode the tops of the ducts as that sediment built up in the gap between the fender and the top of the ducts. Since replacement steel ducts are not available, if yours become damaged beyond repair you may have to replace them with the commercially available fiberglass reproductions. Restoring the ducts is relatively straight forward but removing them takes some patience.
The duct on each side of the car is in two sections that are held together by four bolts. Removing three of the bolts is relatively easy using basic hand tools. You may find the bolts are so rusty that they snap when some torque is applied. The fourth bolt, on top of the duct by the inner fender, is in a very awkward position that makes it very difficult to get any tool on it. Removal is exacerbated by the rusty condition. Removing this bolt is the toughest part of the job. Rather than getting more frustrated than necessary, it is easier to cut the bolt. After the first three bolts are removed, insert a hacksaw blade between the two sections of the duct and cut the remaining bolt. It is a somewhat tedious process since you have to hold the blade in your hand and given the tight space you can only get a limited throw with the blade.
Once the front and rear duct sections are unbolted, each front section is removed first. These sections are each attached to the air scoops behind the grille with two screws. After removing those screws the front half of each duct can be removed by twisting it away from the back half and under the top of the wheel well. Removing the rear sections of the ducts entails a little more work, but is still relatively simple. Each rear duct is attached to the passenger compartment and the inner fender. In the passenger compartment, the ducts are attached by four screws. To remove those screws you first have to unscrew the air deflectors (01820). The duct on the driver’s side is attached to the inner fender by two screws. To gain access to the screws the battery has to be removed. Then the control cable has to be slipped off the flapper valve shaft. The duct on the passenger’s side is attached by five screws. To gain access to those screws the heater blower motor assembly has to be removed. As with the driver’s side, slip the control cable off the flapper valve shaft. Finally, to remove the rear duct sections the inner splash shields (16102, 16103) need to be unbolted from the inner and outer fenders. Then the rear duct sections can be pulled out of the wheel well.
The outside of the ducts will likely be covered with dried silt, rust, scale and undercoating. This can be removed using wire wheels, abrasive discs and putty knives. After removing the loose scale with a putty knife, I found that a 3M Scotch-Brite Paint & Rust Stripper abrasive wheel did an excellent job of getting the outside of the ducts to bare metal. The inside of the ducts will likely have a slight coating of rust. Removing this is more difficult given the length and shape of the duct sections, but a long handled wire brush and emery cloth can access much of the inside. Each rear duct section contains a flapper valve with a rubber seal. The flapper valves are removed by pulling the shaft out of the valve. This is easier said than done since the shaft is probably rusted into the valve. By using a rust penetrant such as B’LASTER PB Penetrating Catalyst, you should be able to pull the shaft out of the valve using a pair of Vice Grips. You may want to buy new flapper valves and shafts if the valves or rubber seals are in poor condition. Depending on the condition of the ducts, the rear sections especially may have rust holes in the top half, particularly near the flapper valve shafts. To repair these you may have to weld in new patches. If the holes are relatively small you might get away with using body filler. If possible, the ducts should be bead blasted to remove all signs of rust. Prior to painting, the ducts should be treated with a rust preventative as part of the restoration. I strongly recommend using POR-15. It not only stops rust, it leaves a hard, glossy black finish so additional paint is not required. The outside of the ducts are straightforward to paint, but the insides present a challenge given the geometry. An extension wand on a spray gun can adequately reach all of the interior crevices. There is also a simple “poor man’s” method. First, paint as much of the inside surface that you can reach. Then, seal one end of the duct section with plastic and poor some paint into the other end and turn the duct to distribute the paint over the interior surface area. Continue to do this until all of the visible surface area is coated with paint. Drain any excess paint and this procedure for the other duct end. Although this is not an efficient use of paint, it gets the job done.
After the ducts have been cleaned and painted, and any flapper valves replaced as necessary, installation is the reverse of disassembly. You will need to purchase a new gasket set before installing the restored ducts. The gaskets can be held in place during assembly using a suitable adhesive such as Sure Tack. You will also need new hardware, especially the bolts that connect the front and rear duct sections. Those bolts, which are so difficult to remove, are much easier to attach, even that troublesome fourth bolt. Properly restored, your steel air ducts should remain in excellent condition for many years to come.
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