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MG MGB Technical - New K&N Air Filters

I'm putting K&Ns on my '73 B/GT with HIF4 carbs. My initial question: should I change needles? If so, what needles do I use?

When it came time to putting these on, I ran across a couple problems - leading to a couple more questions:
1. The spacers provided seem to be too long - leading to two additional problems. There is not enough protruding thread on the bolt ends to securely attach to the carbs, and the filters themselves are loose between the front plate and the bass plates.
2. The front plate that covers the two filters is of abominal quality. There are pits and bubbles throughout the casting that make me wonder if there is more air than aluminum in this piece! This may not be a functional problem, but it was my first exposure to K&N "quality" and I'm starting to have some doubts.

Thanks for reading.

Allen
Allen Bachelder

If you are using a K&N base plate, be sure to order stub stacks too. Those right angles do awful things to air flow.
C Holm

Allan,
#1 ] If the filters are loose, then the spacers manifestly ARE too long!
#2 Bad stuff masquerading as top quality for outrageous prices has me in a tizzy too,
#3 My story from yesterday: I have a B (79 w/ SUs) here, the subject of the "Filtering Air, Oil, and Morons" thread. As I have got into a time bind, I swallowed hard and ordered the tapered K&Ns from Moss, since the guy decided to come this weekend to get the car, and I don't have time to make something better, and that would cost him more anyway.
There is a supplied cork gasket for the filter/carb joint, about 3/16 thick - why? On trial fit, the design of a stud for the top held by a big Pozi screw, results in the screw head being hard against the vac chamber. Hence the thick gasket. This means that there is no way to positively tighten the filter, without
a) distorting it;
b) having it come loose eventually;
c) leaning it hard on the very precision chamber wall, with evil result:
d) having to order special gaskets when you need a new one, which you will, because thick cork gaskets loaded like that WILL fail

I had never looked at one of these tapered ones before. I stupidly thought, given the price, that the stub stack was included - NO F***ing way! Anybody purporting to sell "high performance" filters to replace the superb B design, and supplying this crap, should have it stuffed up his yitz. For these prices he gets both of 'em up there.
I can easily suggest several ways these thieves could correct the design, at little cost, but I ain't gonna, unless I get paid for it. But I will be sending a variant of this post to all concerned parties! I will be making my own hereafter.
FRM
FR Millmore

Are they the tall K&Ns that would fit into the standard air cleaner, with a ribbed long outer cover that has MG in the middle between the carbs?

That is what I have, and the filters are just nipped between the original alloy backplate that located the paper filter and the flat front plate.

If the spacers are too long reduce the length a little until the filter is just held.

I swapped my needles for AAA and it seems to be running fairly near right.
Martin Layton

Allan-
Got carried away - send the junk back and stay with the OE paper elements. The B is perhaps the best filter design ever as OE. If you really want to fiddle, I have posted the reasons for the OE cans, and what to change if you alter them. I will send you a copy if I can find it.
FRM
FR Millmore

Allen. I made some end caps for OE replacement K & N filters for both HS 4 and HIF 4 carbs. Obviously your spacers are too long. I used 1/8" thick aluminum to fabricate end plates and used cork gasket material glued to the plates to seal between the plates and the filters. I was able to use the stock bolts for the HS 4 but with the HIF 4 I had to buy some longer bolts. I always thought the Long aluminum ends cape for the filters Moss and others sell were not made by K & N.

Recently I switched to another type K & N filter on MY 74. It's an RU 4410. They clamp to the stock back plate with worm drive type clamps. The backing plates are installed with short button screws in place of the OE bolts. The bolts are removed from the air flow path and the filters are easy to remove. They do look a little small but I didn't need to change the mixture setting when I installed them. I have a photo of them in my Yahoo photos.
http://new.photos.yahoo.com/flash1929/album/576460762322215690/photo/294928804339596819/20
I hope you can view it.

I don't think the K & N filters flow a lot more air than the stock paper filters. I used the paper filters when I first made the end caps and needed to change the mixture settings after the filter cans were removed. After switching to the K & N filters I had to make a very small mixture adjustment. I have a Sean Brown modified head and have switched to AAA needles.

Clifton
Clifton Gordon

I think that "Up his yitz" thing is gonna hurt. I'm with you F. R. Had two failures today on two "in the field" electro-mechanical devise's that uses a 1 Hp motor. Assembled in Mexico with parts from God only knows where. One was a second failure in three months. All have bad stators. A call to the tech service department we buy these units from says that he had 5 calls in today for the same thing. One fellow in Wichita Ks. replacing his for the third time. The manufacture has no service bulletin notices out but get this... they do have a retro fit kit to eliminate the mechanical stator with an all electronic starter. I'm sick and tired of the lowest bidder contract, cut any corner crap and send it out the door mentality in this country. I'll pay for a quality product but because most of the rest of the world wants it at the "lowest possible price" this is what we get. I don't bitch about the price of anything anymore.. not even gas. Want me as a customer? Build something you'd be willing to put your own name on and stand behind it. Sorry, this thread was about crappy air filters and the laws of physics and their relationship to the yitz.

LaVerne
LED DOWNEY

Hey guys, thanks very much for all your help and support. This engine has run about 20,000 miles since rebuild, but my plan is to get a Peter Burgess fast road head and Piper 270 or 285 cam for it. The K&Ns are probably of no consequence until I get the rest of the stuff done.

Sorry about my "abominal" spelling! 8^) Let's try "abominable".

C. Holm - I hadn't planned on using substacks because the
K&Ns are "designed" (if I may use that word in this context) to fit with the base plates from the original filter assemblies - which, I presume, serve the same function - rounding out, and "trumpeting" the edges.

Fletcher - Thanks, as always. I was under the impression that the real "experts" strongly recommended the K&Ns You are entitled to a chuckle over that at my expense. I've already oiled the filters, so too late to send 'em back. Besides that, I bought these from Gordon at The B Hive and he's just too nice of a guy - I can't do this to him.

Martin - Yes, they're the same filters as yours, and - Clifton - I think they're the same size as yours. Only, like Martin, I bought the cover plate that covers both and has the MG logo on it.

I had presumed that I'd have to cut those spacers down to make the things fit, but thought it better to ask first and cut later. Also, it had occurred to me that perhaps the problem was that the holes on the cover plate were supposed to be chamfered enough to locate the ends of the spacers and countersink them 1/8" or so into the plate. At any rate, I will now cut, although I might experiment first with some tube stock.

I can also see that the whole is going to be quite a mess to hold together and install at the same time.

LaVerne - I totally agree. Give me quality first. I don't want to get ripped off for it, but if well-made things (built by workers who earn a decent living in a clean environment) cost more, so be it. At least I'll be proud of the result. Junk is junk and it is never a bargain. But the worst combinatiion is when you pay high-quality prices and still get junk. That's what K&N has done, and that is really beneath contempt.

Based on your collective advice and some good experience of my own, my other MGB will run original air filters. Fletcher, I'll look forward to seeing what you've written on OE air filters if you can find it.

All - Speaking of yitzes, my wife would like me to install an air filter on mine. 8^)

Cheers,
Allen

Allen Bachelder

Allen-
And forgive my spelling yr name wrong in a moment of, ah, oh, what the hell was it?!
Yes, the OE baseplates are as good as it gets.
The point of the K&N elements is that they flow extremely well, even when they are getting very dirty, and thereby eventually reducing the flow. Paper filters can flow that well clean, but it drops off as they load up. If the car has marginally sized filters, and most do, then the K&N makes a big and increasing difference. However, since the OE B filters are excellent in both design and sizing, the K&N advantage in this case, is mostly for extended use without service, or in very dirty environments. Since the paper elements can easily go 12000+ miles without service in normal paved highway use, and are cheap and easy, I see little point in trading off those virtues for the pricey K&N. I think that will still hold for any likely B street engine you build. On cars with less adequate filters, that may not apply. And keep in mind that the paper elements normally filter a bit better than the K&N when new, as was seen in a recent thread.
You can always fit an air filter restriction gauge if you are really OCD!
The other issues with needle selection enter when the cans are dumped,following is the copy of the relevant bits from earlier.

The flow through the snorkels is somewhat restricted, though far less than with the holes (S&H filters), but this is compensated by the needle selection; the OE needles are only right, or close, with the filters in place. The point of the snorkels is first to accelerate the airflow beyond supersonic levels, meaning that noise is literally sucked into the engine, since the air goes in faster than the sound goes out (sound only travels in the air). This is a big issue since the advent of noise regs, and it is illegal by US Federal law to alter or modify the air intakes on modern vehicles for this reason. The second effect is that large bits of crud are centrifuged out of the airflow and fall to the bottom of the filter case, or are buried in the filter where the air hits it. That leaves the rest of the element clean to get out little bits, and the airflow is now slow with a small pressure drop, so it flows well and cleans the air nicely.
Some cars, like XKE, will not pull the hat off your head at high engine speeds without the air filter snorkels in place. I used to routinely test to 6000 redline in third, and without the snorkels they would not go over about 4800.
The snorkels on MGB are primitive in the extreme, it is far better to have a radiused entry as in good carb inlets, and all modern vehicles have that. It would likely call for revised needles if you modified them in that way. It always mystified me that the MGB filter backplates were the best in the production world, with their nice radiused entry, but the filter snorkels were so crude. I guess it just spoke to a different guy spec'ing the carbs, compared to he who did the filters. You will note that MGB filter cans have the tubes tangential, to give the centrifuge effect. Spridget ones do have the radius entry, and the more desirable tapered profile, but those are centered, so they don't centrifuge, and just drive the dirt into a small area of the element. And, the Spridget ones do not have the nice radius entry backplates! Go figger!
FRM
***************
I was considering for my B the stock paper filter with the stock baseplate but with just a flat cap on top, open sides. Wonder if this is going to seriously affect my engine performance?
*******
Mike-
It will be noisier. It will likely go somewhat lean as the speed goes up, possibly enough to cause problems. If it noticeably affects performance, it's because it's way lean on top, and that leads to fried pistons if you keep it wound up for long. Seems like a nuisance to sort new needles if that's all you change, but if you do other mods so you need new needles anyhow, why not? Filtering won't be compromised all that much, though water could be more of an issue; we used to sometimes have trouble on Volvo 122 with exposed filters getting wet in heavy rain or snow. Took a while to figure out why they acted rich in wet weather, since they would be dry when they got to the shop, but one came in frozen solid one nasty winter day.
The centrifuge effect is elegant (and free!), used in a much more developed form on heavy equipment engines in dirty environments, to take out most of the dirt before the filter element proper. Even big truck filters have the air passing through a set of "turbine" vanes before the element that cause similar action. You have to empty the case periodically, but the elements last a good while.
FRM
FR Millmore

Fletcher,

Thanks VERY much! Lot's of info here. When a guy offers that much help, he can spell my name any way he likes! That is not important to me. Clifton has suggested AAA needles. ' Need to make the switch soon if I'm going to avoid burning pistons!

Cheers,
Allen
Allen Bachelder

Yr welcome! Spelling is just like adjustments - it's a matter of right, wrong, or opinion - pick yer poison.
Piston burning is not that much of an issue to a sensitive driver - it is obviously unhappy if that lean, so you shift or back off. The operative words being "...if you keep it wound up for long."
FRM
FR Millmore

Man, for a guy who thinks he knows a lot about these cars, I still have soooooooo much to learn! But it's not like me to keep an engine wound up for very long. I can't stand the sound of a B engine winding much more than about 3500 for more than a few seconds. Without overdrive, I cannot push these cars beyond bout 60 mph for that reason. I know the engines can take it, but the fact is that I can't. My psyche has a much lower redline than my MGB.

Regarding spelling: with a name like Allen Bachelder, the chances of spelling and pronouncing both name right are practically nil. There are three generally accepted spellings of "Allen", of which my spelling is the least common, and those few who spell "Bachelder" correctly, invariably pronounce it wrong: "Bockelder". Those who pronounce it right (BATCH - elder) invariably spell it the same way - phonetically. That's not "wrong" as there are 39 known spellings of this English name - including Batchelder. My oldest ancestor in North America spelled it "Batchilor". So what's to get upset about?

If a guy can spell "MG", that's all I need!

Cheers,
Allen
Allen Bachelder

Me canna go lessen 75 for more than a mile...
OD would only raise it to 85.
Norton passes 80 at 1/4 mile from the house - that's in the uphill direction.
Got a Mazda, car with 5, always looking for 6.
Had a truck with 13, always looked for 14!!
Never crashed, no tickets (well, one speed trap 45 in 35 at the edge of a small town at 2am - 1982), a million miles.

Why on earth are you modifying a B if you can't drive it above the stock torque peak at 3000, and approach the power peak at 5400?? And any mods will raise those points.
Am gonna come up there and take you driving!
FRM
FR Millmore

Hey Fletcher,

You just took the bait! Just what I wanted - a guy who really knows these cars to come right to my doorstep, take me for a breath-taking ride in my own B as well as his, observe my driving habits and critique them, and tell me what I need to do to get my B to run the way I want.

It doesn't get any better than this. We'll have the beer (or other beverage of your choice) waiting, along with fresh sheets in the guest bedroom and a hearty meal or two.

But just to correct the record - on acceleration, I'll cheerfully redline in every gear. BUT, the engine has got to be doing its part. If it flattens at 4 grand, I'm not going to squat on it. And mine doesn't flatten at 4. In first or second, it's reasonably happy to churn up to 5 or close. But in 3rd or 4th? Forget it. I don't mind downshifting, but I like my neck to snap; hence the urge to modify. I'd cheerfully wind to 6 if it would yield some return on my investment. What I don't like is cruising at 4400 rpm... or 4000, or even 3600 for that matter. I don't want to hear all that business for hours on end. (Mind you, I think nothing of 1,000, 2,000, 4,000 (or more) mile trips. Listening to the B engine whining away at 4 grand for eight hours a day is not my idea of pleasure. I don't need 4+ grand to keep the car cruising at 75 mph while carrying on a conversation with my wife about what color she wants to paint the bathroom.

On second thought...

Allen
Allen Bachelder

Yer on!
Expect me and my daughter after she gets off school sometime, she hasn't been up that way, though we've gone as far E&W as possible.
Just straightening out a customer car (the filter one); I have no idea what the engine is; has a 1500 head on the OE 79 block, SUs, goes real good (now). Must have a cam and maybe some head work. And lowered to CB height with stiff fronts and blocks in the back. Was checking the 80 mph vibration out today - just took another 10 oz of weights off the back wheels. Sunshine, blue sky, country roads, a good B!
FRM
FR Millmore

Alright! Let me know when your daughter is out of school and you have some spare time. We can arrange the rest off the list. Let me know in advance what spares (needles, etc) I might want to have on hand in case a bit of tweaking becomes desireable.

Cheers,
Allen
Allen Bachelder

OK!

Just got back from the test of the K&N and wheel balance fixes.
I machined 1/4" phenolic spacers to fit the K&N, works fine now. They have "Metric" nuts, and if they seize on the threads, then it may be impossible to get the air filters off the car at all, since the threaded post will turn inside, and the big Pozi screw is locktited in. - great design, guys!! GRRR.
Now that I took the 10 oz off the back in addition to the 9 off the fronts (left one oz on LF wheel), it doesn't shake up to as fast as it will go - 5000+ in 4th. And it do corner!

FRM
FR Millmore

Gordon:
Couldn't get to your photos. Yahoo spit it back at me.

Allen:
How would like to have a name like Muenchausen? The odds are even steeper against most folks getting that right the first time, tho some do. Amazing.

Bob Muenchausen

http://www.mintylamb.co.uk/suneedle/ Very easy site for comparing needles, if you get into that. You can do 5 at a time.
Bob Muenchausen

My experience with the stock air intake system is that iit is inadequate for a modified engine.

As has been mentioned several times it is not the filters but the snorkels that are the "bottle neck".

A super quick fix is to remove the tube connecting the filter housings to each other. I solved the problem cheap and quick by cutting a 3"x3" hole in the covers on the sides facing each other.

The snorkels are actually there to clean the air. The small hole results in air being sucked in at hi velocity. This causes dust and other junk to fall out as it does not accelerate as fast as air. Industrial engines use this concept and swirl the air which throws the dust to the outside container to be emptied later. The snorkels also dampen the carb sound under acceleration.

I went down to my local parts store and found a cylindrical paper filter that will sit nicely on the stock filter base with it's efficient opening. Put a paint can top and run two long bolts down through to the carb and you suddenly have a hi performance intake.

It is, however, still taking in hot air. Hot air expands and has less oxygen per cu foot than cold.

For more performance boost cold air from the front of the car should be directed to the carbs. Some people just direct a 4" flex pipe throught the radiator mount and point it to the carb intakes. Obviously a cold air box bringing air to the carbs at exterior ambient temperature is going to be better than a system that supplies heated expanded low density air to the engine.
Barry
Barry Parkinson

Bob,

The only way I can get "Muenchausen" right is to check it everytime I address you. (I just copy-pasted it from your last post). And as for pronounciations, you must hear a new one every day. The biggest problem with pronouncing "Bachelder" is that everybody presumes it's German, when in fact, it's English. Same origin as "bachelor's" degree.

But on to MG matters: thanks for about the neatest website I've ever seen. Having checked Burlen and Burgess books, and observing the collective wisdom on this thread, I'll probably go for the AAA needles.

Thanks, all!

Allen
Allen Bachelder

Yeah, Allen, I know what you mean. I get Murchenchasen, Mullenheiser, etc, etc. all the time, especially by folks from call centers. When you look at the mispronounciations, one has to wonder if they can read since most of the letters they use aren't even there! Glad you like the site. Another greater site is Paul Tegler's SU area: http://www.teglerizer.com/sucarbs/index.html Lots of good info and sites to check out. Many of his sites are for Hitachi SUs as used on 240Zs but don't let that throw you, Hitachi made them under license from SU and they are very similar, and the tech on those sites if at least as good if not better than on most British SU sites.
Bob Muenchausen

This thread was discussed between 19/04/2007 and 26/04/2007

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