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MG MGB Technical - K&N air filters

I intend to fit a pair of K&Ns to finish of the rebuild of my Roadster engine. Is there a difference between the ones that come with the Ali.oval plate with the MGB logo on and the round chrome individual circular ones. I understand that they need to be deep to be most effective. I also intend to fit alternative needles.
Trevor Harvey

Hi Trevor

The ally plate ones use the radius plates from the originals filters the round ones need a stub stack of some kind to allow smooth flow into the carb mouth.

Peter
peter burgess

Trevor,

Last weekend I fitted exactly what you are considering to my 67 roadster. I had no difficulties with the kit installation although I found that the aluminium tube spacers were a bit sloppy on the bolts. The effect was an unpleasant jingling sound when running that was cured by some quality electrical tape wound around the bolts a couple of times prior to passing through the spacer tubes.
I have noticed a great difference in the breathabiliy of the engine and am now working on the mixture setting as with the increased air flow things have leaned of somewhat. There is a large difference in the induction sound, which I quite enjoy, but if you prefer things on the "quiet side you may want to think this over!

I think they really add some interest to the setup of the carbs! Go for it!

I have thrown in a pic to show you the setup, excuse the rough state of the bay, it is a work in progress!

Regards,


C Brennan

Thanks for that. Them ovals look good. I will go for a pair of them.
I got the engine fired up again today after a major rebuild. Great to hear it running again. One more job can be ticked off the list.
Trev
Trevor Harvey

Reminds me of when we put an HS6 on my friend's midget. The K&N was offset, may have been a Metro manifold too, and we didn't check the clearance with the bonnet... Hey presto, power bulge!

Make sure you use the right ones or check the clearance!

N :-)
Neil22

What needle do you need for K&N filters
Tim
TS KING

The supplier suggested to get the best from the K&Ns alternative needles were advised. They wanted the tag number off the float chamber and will send what they think best. Normally AAAs. I am awaiting delivery. Trev
Trevor Harvey

The suppliers did send AAAs. I have read before that most people fitted these with the K&Ns.
Trevor Harvey

Here, http://www.britishcarforum.com/bobmuenchausen/17963.html , is yet another option that seems to work well.
Robert Muenchausen

The bolts are supposed to tighten down solid on the distance tubes. That's what they are for. If they don't there's something wrong, and you can reasonably expect the filters to fall off in due time.

FRM
Fletcher R Millmore

I fitted the large K&N filters, that are used with the oval backing plate, in the original housing. I felt the AAA on my HIF4's are on the rich side. I now run the standard AAU, but I'm considering fitting the older "rich" needle (is it 5 or 6?) that is nicely in between the AAA and AAU. That needle needs to be modified (sleeved?) to fit the HIF but my supplier is able to do that.

The "flow" of original radius plates is quite good and much better than the "flat K&N with round backing plate". Those flat filters should really only be used with the K&N stubstacks.
Willem vd Veer

I'm using the K&N pancake filters, with the original alloy backing plates. I cut a bigger hole in the stainless back plate of the K&Ns so the backing plates fit outside the filters. Airflow must be OK since we got 104RWHP on Peter's rolling road.

Here's the view from behind. I'm holding the K&N stainless backing plate, with the alloy plate from the original can in place


D Balkwill

Here's the view from inside. I made gaskets to make sure there wasn't a leak.


D Balkwill

Fletcher, which sort are you talking about? If the ones I posted, they are used in racing all the time as well as road cars and seem to stay on pretty well with just the ring clamp at their base attached to the OE bases. The point of going to that style of filter was to obviate the obstruction and turbulence of the OE style through bolts and spacers. You could ask Hap about his experiences racing with these. I, being only about 150K miles into my K&N million mile warranty, am sticking with the ones I already have, which are as you describe.


Robert Muenchausen

Bob -
I was referring to third post at top, C Brennan. " I found that the aluminium tube spacers were a bit sloppy on the bolts. The effect was an unpleasant jingling sound when running that was cured by some quality electrical tape wound around the bolts a couple of times prior to passing through the spacer tubes."

If the distance tubes can rattle, then the bolts aren't tight, and they will fall out after a bit. I don't know what that setup uses for fitting bits, like the neat grommet/washer arrangement of the OE ones, which you appear to be using. Whatever it is the bolts should have something to tighten against, and the tubes should give the correct amount of compression on the elements to seal correctly with the bolts tight. It's especially bad if there are any kind of small loose pieces inside the elements, like lockwashers to ingest and causes dyspepsia! I've heard unpleasant stories regarding various crappy filters that let pieces get ingested.

I remember when Hap came up with those clamp-ons, very neat indeed; always wanted to ask him if he got K&N to make those or are they actually for some other application. And his various bolt arrangements are good too, if they have Locktite or something on them. I do think I might machine a shallow groove or two to improve the security of the clamped element on the backplate.

FRM
Fletcher R Millmore

Hi Fletcher...the tubes are often too short so the threads on the bolts bottom out before the spacer tubes are pinched.

Peter
peter burgess

Hi Peter -
Well that calls for some customer complaints for sure. Do they bottom because the element is squashed, or because the bolt thread runouts are killing the carb casting? Why do they bother to send the tubes if they don't do anything but annoy you? Why do people make, sell, and buy such crap? It's a good example of why I tend to stay well clear of the sellers of "performance upgrades" in general, and the confusion they cause among their customers. Really hate that you have to examine every single piece before figuring out if it will fit, or work, or kill you or your wagon!

FRM
Fletcher R Millmore

Hi Fletcher

Sadly we have to inspect every thing we buy so we can make sure it has the correct components in the box and the item is fit for purpose before we can resell. With the filters, some tubes fit some don't, we sometimes have to fit flat washers to add a little length to the space tubes.

Peter
peter burgess

I really like the look of the K&N's Hap fitted - thanks Bob!

Colour me interested... I'm gonna see if i can find them locally. What needle are you running & I'm assuming you have a polished head rather than anything more exotic?
Curtis Walker

Curtis, if you go back to my original link, the K&N # is on my webpage. With any luck it is the same for you in NZ as here in the US.

For my HS-4s, I use just plain old vanilla #5 needles. I get decent power, and 26 MPG on average and as high as 36 MPG (w/OD) on the road. This may not be the ideal needle depending on what you want your car to do, or what cam you may have chosen. My car is pretty much a stock 68 MGB with only minor refinements, no major modifications. No polished head, or other tweaking from stock other than a 2" ID exhaust system from the down pipe on.
Robert Muenchausen

This thread was discussed between 22/02/2010 and 24/03/2010

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