Practically Classics Forum

I have a Weber 28/36 carb on my Rootes 1725 engine and fitted it with a flat chrome mesh/foam type air filter and find that it's very noisy (sucking air noise).I assume that it's typical of this type of filter but before I go to the expense of replacing it with maybe a KN type does anyone have any suggestions for an inexpensive fix.

I've a k&n on my vogue and it's fine, not noisy at all



Kev

If a K&N is given the correct dose of the oil that comes with it, then it will, as Kevin has found, be perfectly quiet enough but cheap foam filters aren't oil baths like the K&Ns are, and as such can be really annoying to say nothing of their woeful filtration capability. We tend to refer to thae foam pancakes as a rebore that happens as you drive. Sadly, the way in which the debris that they allow through impacts upon your cylinder walls, rings and pistons isn't that precise, I've seen all manner of engine damage caused by them, bin it and fit an O/E filter or something like a K&N; oil bath filters that use a thick grade of fabric and are as effective as O/E though rarely any more so.

Hi chaps,
Thanks for the input.Looks like I'll invest some cash in a K&N or similar.

Regards
John

This is what I fitted first (i do have the OEM filter box but the filter elements are unavailable),




I found a few issues with it:
It was Noisy
The filter foam started to fall apart under use (probably due to its age)
I couldnt get the air/fuel mixture set to an acceptable level.

Get either a K&N or something from a classic that takes an available paper element, I was looking at some of the Ford Pinto filter housings before finding the K&N at a decent price.

As previously said, it is quiet and along with the NOS Carb that I fitted, the mixture is now spot on.

Kev

I fitted one of those to my herald for a season Kev because I thought it looked cool! But I too found it noisy and it seemed to reduce the already pitiful power even further! went back to the original air box and filter. Much better!

Hi Kev,

The Speedograph is what I have fitted and I also am having difficulty getting the carb tuning sorted ,so I'll definitely be sorting a K & N type.

John

As above the foam filters are a poor substitute and a K&N is better........although, in my opinion, not as good as the original set up. Also with regard to Johns comment on it being an oil bath filter! Not exactly they are sprayed with a film of very light oil, you can't dip them in GTX and bolt them on.

When on a steady throttle opening just cruising I like no induction roar or exhaust noise. I like a muted growl when accelerating.

The air filter is also a flame trap. For both the carb and the crank case if the breather is fitted to the air cleaner.

Never run a breather into an air filter with out provision for a flame trap.

A crank case explosion can blow the bonnet off the car.


In the 1940s Harland and Wolf in Belfast had a crankcase explosion in a ships engine room and it killed 20 crew.

Rover V8 have liitle grey cans in the breathers.



Bob

Minxy wrote:....with regard to Johns comment on it being an oil bath filter! Not exactly they are sprayed with a film of very light oil, you can't dip them in GTX and bolt them on.

You certainly shouldn't be doing that with a K&N, no, and it's as well that you pointed this out just in case someone read this and assumed that all oil bath filters are designed to have oil splashing about inside them then, as a result of this assumption, filled their air filters to the brim with engine oil and consequently caused their engines to ingest so much fluid that they suffered hydraulic lock and broke down.
Technically, the K&N is an oil bath. The fabric is only there to carry that oil and if used dry, the fabric will - in an ironic twist - become less able to breathe properly.