Morris Minor Owners Club

Has anyone ever fitted a K & N filter element into a standard Air Filter housing, the reason I am asking is that the new car I am getting has a K & N fitted which as you all know is a little noisy due to its open construction so I wondered if anyone had one in the standard filter housing to reduce the noise level, if its possible I will probably look to remove the original input pipe and replace with a larger bore one.

I had a K&N on my saloon and it caused nothing but trouble as it was making the mixture too week
By putting the K&N filter( the shallow cone shaped one for the mini)into the moggy housing this reduced the airflow and restored the running of the engine.
Doing this omits any benifit the filter has on the breathing of the induction system...but it does quieten the noise.
And can be cleaned and reused every time yon service the engine...

GAS.............

The great 'Vizard' does say in ' the book ' that the standard air filtter with a new element gives 1 of the best air flow rates... .. some have suggested that a couple holes in the element metal case can help.

The Minor casing has a very restrictive pipe on it - So a few holes would help. Also making sure the end of the pipe has a nice rounded end is a good idea.

A stub stack (I think that's what they're called) inside the filter on the carb mouth would do wonders, probably as much if not more than sorting the casing out.

I dislike the bare cone or pancake filters - They sit right above the exhaust so breathe lots of hot air. A free flowing filter inside a casing, with a cool air feed is probably the best way to go for both performance and noise. Or sacrifice a little flow at the carb mouth and fit a Mini "elbow" and filter casing so you can use a bigger element and run a better cool air pipe to it.

An engine that runs too lean with a good filter on shows the filter is breathnig nicely - But it also means you need to stop being so tight and fit a better suited needle!

As far as I am aware you can not get a K+N element to fit straight into the Minor filter housing.

I have fitted a cone type filter into the housing though. The filter slots onto a tube and clamps on. I had quite a bit of adapting to do (welding etc). I also put on a larger diameter feed pipe on the casing with a nice trumpet end (a ram pipe). I ensured that the entrance to the carb was nicely radiused.

However I do think the filter would only flow 70bhp. This wasnt really a problem as they were twin carbs on my Dads MGB powered A60.

If you fit a K+N (or do any modifications) you MUST get a rolling road tune up to realise all the benifits. A K+N filter will make the mixture weak because it flows so well. Get the correct jetting and make the engine more effecient.

If you do not get a rolling road tune up you may as well leave the engine standard.

John

Should only weaken the mixture at high power outputs - normal running the standard filter can easily flow all the air that's needed - provided it's not choked with dirt or soaked in oil from the breather pipe.

The Minor casing has a very restrictive pipe on it - So a few holes would help. Also making sure the end of the pipe has a nice rounded end is a good idea.

or just remove the pipe and make the hole a bit bigger? Obviously not as well flowed as a ram pipe, but surely better than a restrictive long pipe? (or am I missing something?)

Kevin,
If you've a standard engine then the breathing restriction is the filter casing NOT the filter element (assuming you're using decent one like Cooper AG122 from B Motif at about £4). You can prove this to yourself by fitting up a water manometer to the back of the airfilter body (drill a small hole and araldite in a bit of brake pipe and then run some windscreen washer pipe into a loop taped to the dash) and you'll see that the pressure drop across the lot at full throttle at 65 mph is about 6 inches of water, ie about 0.2 psi. (At least it is on my rather tired 1098). If you take the filter cover of and expose the paper filter itself holding it on with a big washer (about 3 inch dia) you'll about 1/2 inch pressure drop if really filthy and about 1/4 drop if clean. And you get the full intake roar for free!
So in my view unless you're sucking a lot more air than standard, stay standard. Regards, MikeN.

rayofleamington wrote:or just remove the pipe and make the hole a bit bigger? Obviously not as well flowed as a ram pipe, but surely better than a restrictive long pipe? (or am I missing something?)

Not sure - The hole will be picking up even hotter air, and if left "flat" might be more restrictive than the radiused (that'll be the word I couldn't think of earlier) pipe!

Really the standard Minor filter casing isn't made for performance though, so it's always going to be a struggle to keep it and go quicker, I'd have thought

Without sounding completely thick, what is the best way to have the tube in summer? I know I want the air to be as cold as possible, but I can't really change much, other than have it at the top of the exhaust manifold, or halfway down it. This because my tappetcase breather tube is in the way.

Mike N,

I like your practical approach to demonstrate the restriction.

You can also do the same with the exhaust (and probably be horrified!)

I also use the U tube manometer for basic aerodynamic work such as where to put vents in the bonnet and wheel arches.

John

The great 'Vizard' does say in ' the book ' that the standard air filtter with a new element gives 1 of the best air flow rates...

I dont remember seeing that applied to anything but the MG Metro housing.

If you've a standard engine then the breathing restriction is the filter casing NOT the filter element

No its got a 1275cc in it and has previously been modified with a K & N cone filter which is noisy as expected and just wondered if it was posible to fit the filter in a modified standard housing to reduce the intake roar, as I said in my posting I will look to remove the original input pipe and replace with a larger bore one.
Looking at Johns reply it is possible with a bit of messing about so this will probably be the route I will go down and as the current owner hasnt got a clue as to if it has ever been set up properly, I will take it to a rolling road to have it set up corectly afterwards.

If you look at the sizes of K+N that are available you will find that not many actually fit the standard Minor case and flow decent figures!

I would be tempted to find a case that looks like a Minor case from a bigger car and use that, it will be a lot easier......trust me!

The other option is to mount the filter in the front grill panel area and then duct up to the standard housing, modified to take the flexy pipe. It all depends on how standard you want to keep it looking.

John

I believe Mr Wanderinstar uses one from a Princess with good results.
I agree with the filter case diagnosis - even an empty case horribly restricts my engine. I did cut some holes along the lower edge - so not seen from above - but still restrictive at full chat.

Someone mentioned to me about drilling the airbox on my old fiesta... with hindsight I probably should learn the difference between a drill and a hacksaw:

(don't worry, it was only a mk3 - the worst of the 'fiesta' range)

I've always used K&N or PiperX filters on my cars, you may need to adjust the mixtre slightly but they do offer an improvment over the standard setup.
As for the sucking noise, I quiet like it.

As for the sucking noise, I quiet like it.

Its not so much the sucking noise I object to its the intake roar, probably something to do with my old age

Its great when pulling away sounds like you're taming a real beast of an engine but when you're bellting down the motorway and it feels like a motorhead concert it isnt so fun.

nothin' wrong with Motorhead

walks away sing 'The Ace Of Spades'

it feels like a motorhead concert

Well I will check it out when I fetch it home as I only heard it around town so to speak and though that was loud enough but Motorhead

Welung666 wrote: nothin' wrong with Motorhead

walks away sing 'The Ace Of Spades'

True but I'd rather be at a motorhead gig

waiting 'till Novemeber, anyone else going to be at Brixton?