Neither of my Austins had air filters but I think a brass mesh screen might be of use in adverse conditions if only to stop the big bits...
The BSA trike has twin Amals and being FWD there is more chance of grit flying up under the bonnet so they have brass mesh screens. (They also prevent the embarrassment of dropping one of those tiny screws/nuts/washers to see it being sucked into the inlet while making running adjustments)
09-01-2023, 09:55 PM (This post was last modified: 09-01-2023, 09:57 PM by Dave Mann.)
Ah but they didn't expect the engine to last 90 odd years. A side benefit of the air filter mounting is that the 22FZB choke is disabled and replaced with a center pivoted choke in the adapter pipe which can be used when the engine has started, very useful at this time of the year.
The plastic hose goes to one of the valve chest cover holes so it digests it's own fumes.
I suggest it depends on where you live (or perhaps where you drive to).
Like others here, I've never used a filter on my own cars & without obvious detriment.
I see no need for one at all in Western Europe, though on other continents and particularly in desert regions it's quite another story.
I've known at least one person with a downdraught carb who wished they had fitted one after dropping a stray nut down the intake; though a simple mesh is equally effective in this regard.
I fear I might be mocked for hairdressering, but the Ruby has an export air filter, and the 2CV also an air filter. Perhaps more important in the latter case to stop big lumps falling down into the downdraught Solex when trialling or checking ford levels whilst recceing. When filters are being cleaned there is always evidence of what is being kept out of the engine, or perhaps more significantly, kept out of the carbs. We could discuss road surfaces and their improvement over the years, but it is a bit late to start descending into detail about Westrumite, Dustabo, or the distinctly unhelpful Pulvertanto as used at Dieppe in 1908. Tomorrow, perhaps.
This may not relate directly, but I think should be considered. Here on the west coast of North America(Washington State) I rode a Velocette. It had a straight intake with no filter. I didn't have an issue for several years. I then took a tour which included a trip to a friend in northern California. I rode about five miles on a dusty road to his home. On the way back to Washington, I had so little compression it was hard to start. When I got home the intake valve was badly pitted. I think it depends on the environment. A few miles of dust can impact an engine. I would not be averse to carrying a detachable filter for those potential times when I would encounter dusty conditions. This may not be an issue in most environments but something to consider.
It is interesting to note that Austin, generally only provided air filters on export cars. My RK was exported to Sweden from new in 1930 and had an export Zenith FZB carburettor with a central choke spindle and flange for an air filter.
The filter is long gone but I did try making a similar filter using modern foam filters. I found it choked the engine too much so I don’t use it any more.
It is interesting to note that Austin, generally only provided air filters on export cars. My RK was exported to Sweden from new in 1930 and had an export Zenith FZB carburettor with a central choke spindle and flange for an air filter.
The filter is long gone but I did try making a similar filter using modern foam filters. I found it choked the engine too much so I don’t use it any more.
Cheers
Howard
And there's the rub Howard - over the years the cautious have many times eaten the dust of those who tossed their filters into the hedge and seemed to get away with it. If I could fit a filter with no loss of power and no need to adjust tuning - and somehow fit it into the available space - I'd do it tomorrow.
