[ROVERNET - UK] Aftermarket air filter revisited
jaoa27 at verizon.net
Thu Mar 1 06:39:51 GMT 2007
I took your advice, and the old cans are now in the recycle bin. I rigged
this up this evening:
I am not sure of the correct application of these filters, but since they
had the correct ID to seal quite well on the adapter "trumpet" flanges, I
will go with it for a while. I will not get any designed-in restriction
afforded by the original air cleaner housings, but the carbs will get plenty
of air (for a change!). I do not drive in the wet weather so I am not
concerned about the filters potentially getting wet. One day I will stop
monkeying around and use the stock set-up.
BTW, I also corrected all the vent hose routing. I am good to go except for
that charging problem that I am still de-bugging. I should have my DVOM
unpacked by the weekend.
>Further info on the aftermarket filters on Steve Lawrence's TC that I
>berated a week or so back. I have an MGB here with the same filters,
>only for HS4 carbs, and decided that I would calculate the effective
>sizes. I knew they were bad, but this are rrrdiculous!
>Crappy "Stellings & Hellings" filters for HS4 SU. May not be real S&H,
>but the design is so bad as to make this irrelevant.
>These are the chrome ones with perforated chrome sleeves on both sides
>of the foam element.
>Airflow area available:
>84 holes @ .190dia. = 84 x .095sq x 3.14 = 2.38 in sq per filter.
>That is maximum at the inner sleeve, reduced by alignment of the similar
>outer sleeve and foam.
>Airflow area of OE paper, gross:
>3 3/4 D X 2 deep x .8 estimated screen coefficient = 33 in sq per filter.
>Actual element is unfolded size = .550pleat width x 2sides per pleat x
>3depth x 76 pleats = 250.8 in sq.
>Note that ONE pleat has nearly 50% more filtering area = 3.3 in sq. than
>the entire S&H filter!
>The S&H has about 7% of the gross and 1% of the element area available
>in the OE unit.
>This means that not only is it very restrictive, but also that air
>velocity in the media is so high as to make any useful filtration
>S&H also has an bad backplate, further restricting air flow, and it is
>so flimsy as to not retain the gasket, which shrinks into the intake,
>making it worse still. The car I am working on has about a 1 1/4 hole
>through the shrunken gasket, which is the correct 1 1/2 original type.
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