When racing in non-dusty conditions, can sidedraught carbies be run without filters? (But still using ram tubes) The reason for asking this is because i've been looking at some pictures of cars with sidedraught webers that are used for circuit racing and DONT run filters. I assume this will give better flow, but shouldnt be done on a car used for street/dirt purposes.

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Cheers,
Tristan.

Daily - '85 XF Falcon Spak Wagon (that I don't care about)

On going project - '79 L18 Powered Datsun Sunny, Twin 45's

Only reason not to is as you've alluded to - the possibility of sucking in stuff and causing wear in the motor.

I've run my vintage bikes all their restored lives without air filters, on the street, mainly because that was how they left the factory. Before restoration, most of the wear from running without filters for years seemed to be in the carb (body and slide, which are soft alloy). I'd say it may be a more viable option on carbs like webbers without many moving parts ? Although I will be running my SU fed L18 with just a trumpet (no filter) since it ingested its decaying foam sock filter last time I started it up

You may also need to re-tune for the different airflow characteristics.

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

ahh I see.... well i've got socks to go over the ram tubes and if they probably need to be re-tuned if i take the filters off for track days, im not going to bother.

Now for my next question, are the "K&N" style filters better than sock foam filters? Or which applications do they suit best?

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Cheers,
Tristan.

Daily - '85 XF Falcon Spak Wagon (that I don't care about)

On going project - '79 L18 Powered Datsun Sunny, Twin 45's

I've never used K&N, so I'm afraid I can't answer that one.

I used both Torana GTR ones and foam socks on my cars with SU's (obviously not at the same time ), and a Datsun 2000 sports air filter in my own cobbled together air cleaner assembly on a pair of Solex carbs.

And if you use foam socks, don't let them sit for 7 years then attempt to start the car. I tried that a few weeks ago - started the car, gave it a rev till it was warmish then went round to check there were no water / fuel leaks etc from perished lines anywhere. Then I noticed that most of the foam socks had vanished . They'd perished and the motor had sucked bits of them in Didn't seem to hurt anything though

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

I raced my old twin webbered 1600 with no filters, never had a problem. From what IU have read, it seems the K&N Style filters do have better flow than the oil soaked foam filters.

With my new set-up (turbo) we are building an airbox which will house a flat panel K&N filter. Tinlet of the turbo will be loctaed in the airbox with a bellmouth on the end of the inlet pipe.

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www.full-throttle.com.au
www.boostcooler.com.au

When the Flag drops........... the Bullshit stops
Go hard or go home!

I always run socks

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1969 Datsun 1000 wagon (Daily)
1969 Datsun 1000 coupe (Next project)
1969 Datsun 1000 coupe (Long term project)
1974 L34 Torana replica (In the build)
1976 SS Torana hatchback (Restoration project)
1976 Cadillac sedan deville (Pimp cruiser)

I've read some (allegedly unbiased) tests showing K&N's flow better & filter better than foam filters. I've since noticed F1 motors running filters that look a whole lot like K&Ns... Never seen them run foam filters.

Interesting that even in F1 they run air filters. Engines only have to last 2 weekends, all the money in the world for heaps of rebuilds, every bit of speed counts - and they STILL use filters.

My understanding is that the dirt they inhale slowly buggers up the ring seal, costing HP. If that's true, it's probably best to run filters.

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Recommended trading: datto-510

K&N's are foam filters are they not, just with thinner foam?
I'm only running K&N's because they were too cheap to pass up. Less than half the price of sox (look ok too)

K & N's are cotton

K&N's flow better, but socks filter better if they have decent thickness in the foam (those ram-pod versions suck!). Possibly urban legend : A trucking company in america trialed K&N's as part of a cost cutting measure but switched back to paper due to the increased engine wear.

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Michael
'71 240Z, RB20DET.
'89 Nomad (needs speed).

Angle is right. K&N's are some woven cotton thingo. They're not foam.

Same report that I read also reckoned the K&N's filtered better than the foamies, but not quite as well as a new, good quality paper filter.

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Recommended trading: datto-510

When i bought my new Foam Filters i was asked whether or not i wanted Tarmac or Rally Filters. The Tarmac ones are not as thick in Foam as the Rally version, i went the rally version as the car gets driven on the street.

Might be worth while finding some "thin" foam filters and having a look at those.

Luke