In the post below (Rattle Can Hatfield) I mentioned a filter inside of the tube coming from the oil filler can. I made several attempts to clean out this filter, and did get some flow through it eventually, but I wasn't satisfied that it would perform as originally designed.
The 356 C is the only 356 that has this element (sometimes called a "flame arrestor"). Previous models did not vent to the carburetor, but instead they had a line directly from the oil filler can down to atmosphere below the engine tin. The venting to the passenger carburetor was likely do to legislation requiring a more closed system. By the year after my car was produced, this flame arrestor was moved, and was inside the outlet tube of the oil filler in the 912.
In the photo below you'll see an example of the 912 flame arrestor. It is larger than the 356 C one, and does not fit in the oil filler of the 356 C, nor in the air filter. It is obvious now that the reason the 912 hose from oil filler can to the carb has different diameters- the oil filler tube is larger because this flame arrestor was installed.
Back to my air filter housing. I decided to remove the part for better cleaning. Below is a photo of the primary screen, secondary screen (finer) and a wad of brass wool. I left the innermost screens in place and was able to clean them up in situ. The full assembly consists of primary screen, secondary screen, brass wool, secondary screen and primary screen again.
After cleaning the screens, I installed new brass wool. Photos show the cleaned original wool and my replacement brass wool.
This was not an effort to get better filtration. It was an effort to make sure my engine vents. The 356 C has unvented valve covers, so this is the ONLY path for engine venting. I guess Miss April just wanted to vent!
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