Think of this post as a community service announcement.
A number of sellers (often via eBay) are now providing Stromberg carbs that have been overhauled. The products are typically either “nice and shiny” from being replated, or dull grey. Some of these carbs appear to have been acid dipped to clean them. If the acid dipping is too prolonged, the carb can be affected badly.
Many of the fittings in a Stromberg carb are a press-fit. The acid can eat out the area around the press fitting, leading to parts becoming loose. Some parts (like the drive plugs) will allow fuel to leak. Another significant risk is that parts become loose and fall into the carburettor throat. These bits can travel into the engine, and do horrific damage. One part that is very susceptible to this is the fuel bowl vent.
Please do not think that all carb overhaulers are making crap product. There are probably many of them doing a great job. However, I have now seen a number of sellers, including at least one “big name” where the carbs have loose parts. At least one engine has been destroyed due to this.
As a check, I’d recommend that anyone who has bought reco’d carbs should do the following. Remove the air cleaner, and take a look down the throat of the carb. You should be able to see a small pipe, jutting up diagonally in the carb throat (see photo below).
This is the fuel bowl vent… the bit that can come loose and wreak havoc in your engine. Grab the vent pipe with your fingers, and try to wiggle it around. If there is any sign of movement, you are at risk of the vent coming loose. The carb will run OK (temporarily) with no vent pipe – it will have an increased tendency to slosh (overflow) fuel into the carb throat, and will tend to run slightly leaner. Under no circumstances should a vehicle be run with a loose bowl vent.
If anyone finds a loose vent, please let me know (no need to name and shame the vendor publicly though)… interested to see if the vendors mentioned above have more problems.
Cheers,
Harv