As the culmination of more than a decade of gradual improvements in the basic Super Six model, the 1929 Hudson is generally free of problems. However, one "improvement" made in 1929 was actually a long step backwards. Marvel Carburetor Co., supplier of carburetors to Hudson and Buick (and possibly other manufacturers) that year, made a cost-driven decision to convert the "float bowl" in its products from bronze to "pot metal."
The float bowl is the portion of the carburetor into which gas flows from the gas tank (on the right hand side of the photo). Conceptually, this works the same way as the tank on a flush toilet, with a valve that lets gasoline flow in until the level reaches near the top, at which time a float-controlled needle valve shuts off the flow.
Making the float bowl out of pot metal was a bad idea from beginning to end. Marvel recognized its mistake and reverted to stronger materials just a year or two later. Pot metal is an alloy of lead and copper. It has a low melting point, is easy to cast, and is cheap. It's also weak, brittle, and prone to cracking under even slight stress. Moreover, it becomes progressively weaker with exposure to gasoline, which tends to "crystalize" the lead in the amalgam. Thus, what Marvel created was a container holding about 1/2 cup of gasoline that was almost guaranteed to crack and begin leaking, in many cases not long after the car was sold. The most vulnerable point is where the gas line fitting (brass) screws into the pot metal casting. This is what broke on our Town Sedan. Many owners also have reported broken screw holes on the float bowl cover. All in all, it's a miserable example of indusrial design, and living proof that things were not always "made right" in the old days.
Various solutions have been proposed to replace the troublesome carburetor, including conversions to a different carburetor of the period. Jack Smith of Manitoba offers a NOS (new old stock) Carter BB-1 and a special adapter plate he has designed, for $900. (Any carb other than a Marvel requires an adapter, because the bolt-holes that attach the Marvel carb to the heat riser are set at a 45 degree angle, but directly fore-and-aft on all other brands.) Some old-carburetor purveyors have told me that Zenith carburetors will work, but others tell me that it won't fit in the '29, because the carburetor is "forward-facing" and thus positioned directly over the generator; there isn't enough room for a Zenith unless you undertake a hugely expensive modification of the heat riser mechanism. One good idea is to replace the 1929 carb with a rear-facing and all-bronze 1928 Marvel -- a "bolt on" solution if you can find one, but good luck -- most the "surplus" '28 carbs were soaked up in earlier years by '29 owners.
In December 2001, Australian Hudson owner John Meadows, to much applause by '29 Super Six owners, announced that he had located a metal foundry willing tackle the complex job of casting replacement float bowls in silicon bronze, and then machining the proper holes and threads into the casting with a CNC Milling Machine. "I just got sick of fixing up the old one," he said. He ordered 10 of the replacement bowls in the first go-around, and he may have a few left if you need one. He quoted a price of $165 Australian, which translates to about $85 U.S. at current exchange rates. This is a real bargain compared with the cost of a replacement BB-1, the least expensive of which I've found is $275, not counting the adapter.
Some advocates of conversion to non-stock carburetors argue that the Super Six performs better with a Carter BB-1 or other "aftermarket" carburetor. They also argue that the Carter BB-1 gets along better with an electric fuel pump than the Marvel carburetor (which an electric pump can overwhelm, causing gasoline overflow from the float bowl), but that problem can be resolved by installing a $5.00 pressure reducer in the gas line). The performance issue may not be valid. Chris and Kelley Purdum, co-owners of Customs and Classics Auto Restoration, recently re-converted a 1929 Super Six Club Sedan from a Carter BB-1 to a completely overhauled Marvel carburetor. Chris told me that the car accelerates more quickly and runs faster with the Marvel carb than it did with the BB-1. "The secret is to make sure you adjust the Marvel carburetor exactly according to instructions," he said. An Adobe Acrobat (.pdf) copy of Marvel's booklet, Carburetion in Relation to Service; How to Overhaul a Marvel Carburetor is available online from the Hudson Super Six Online Library.
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