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Thread: Air Filters for twin 45s

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    Air Filters for twin 45s

    I need some new air filters for a 2litre Rally spec Pinto. I have seen these on ebay and was wondering whether they are any good. Being modular, they are an easier fit. Forgive me if this topic has been discussed a million times before, but I dont want to trawl through hundreds of old posts!
    Thanks Chris.
    https://www.ebay.co.uk/itm/Weber-45-...4AAOSw29ZeFu-h

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    Racer Decade Plus User wildo105e's Avatar

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    Re: Air Filters for twin 45s

    I have used them a couple of times over the years been fine. If you look up John Wilcox BDA i think he used them on his engines and his reputation was second to none.

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    Re: Air Filters for twin 45s

    I my self will never use foam filters ,I have had a few catch fire when the carbs spit back but its all down to personal choice
    Big Wing sold and gone to be a film star

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    Re: Air Filters for twin 45s

    Quote Originally Posted by alancdavis View Post
    I my self will never use foam filters ,I have had a few catch fire when the carbs spit back but its all down to personal choice
    Correct, my advice, only use them in competition where the filter will be cleaned and re oiled after every race.

    When you use them on the street, they start to collect fuel. This is fuel pushed out of the carburetor or fuel injection system at light load (where the engine is what we call "off cam"). The fuel will be washing away the oil, more replacing it. The oil is there to stick the dirt and also to prevent them against fire. It's just a matter of time before there is enough fuel, waiting for a backfire

    Please note, they are very good filters in what they have to do, much better as K&N. But only for racing where service intervals are very short and the filter does not have the chance to catch and collect fuel

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    Re: Air Filters for twin 45s

    Quote Originally Posted by alancdavis View Post
    I my self will never use foam filters ,I have had a few catch fire when the carbs spit back but its all down to personal choice
    I'll risk it. They stick out of the bonnet side anyway as it's a narrow Westfield.

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    Re: Air Filters for twin 45s

    Quote Originally Posted by Memphis View Post
    I'll risk it. They stick out of the bonnet side anyway as it's a narrow Westfield.
    Excellent - loads of oxygen and fibreglass fuel - they'll burn well LOL!

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    Re: Air Filters for twin 45s

    Two things: the risk of setting the air filters alight is especially there when using wasted spark ignition. Then there is a spark when the inlet valve is open .... with a normal distributor ignition the risk of fire of airfilter is not very high.
    The grasstrack boys over here never ever oil an airfilter, it will collect the dust/sand. They just take the filters off after every run and clean them with a brush.

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    Re: Air Filters for twin 45s

    Hold on please, the grasstrack boys DO use oil on their filters. Foam filters where about the only filter you could use in auto-cross. BUT the replaced the air filter every heat. The right guys had oiled filters in plastic bags for every heat, as many as needed. They did not clean them on track.

    Foam filters (oiled) where the only filter that could stop sand from entering into the inlet track. In most cases, they had K&N filters with a foam filter over it. more like an extra security in case the foam filter failed. Several different foam filter models where available. Some of them I had custom made here in Belgium add a large motor cycle supplier.

    I've been a long time into auto-cross engines, with K&N filter you could do one race, your 2 Ltr was a 2,1ltr after one race, bores, inlet guides and valves where all gone.

    They did not had backfires because these filters could not collect fuel as I mention above.

    Backfires also have nothing to do with wasted spark. It's usual a failed inlet valve, but so minor it will not hurt in power, usual because the valve guides are not 100% concentric or right clearance, or temporary lean mixture in one of the inlet tracks.

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