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MG MGB Technical - K&N Stock Air Filters

Greetings,

A while back I had noticed a thread on the use of K&N air filters for use with the early "B" by simply having them exposed and not using the stock cannisters.

Obviously the size of them would allow more air flow as the non use of the cannisters would not restrict air.

My question is, what size circumference plate do you use on the top side to secure the filters in place, I recall someone saying they bought and fabricated something from a building supply dealer ?

I currently have the coned shaped K&N's with the stubby stacks inside. I am not sure but since installing the stubby stacks, I have noticed better performance ? Is this wishfull thinking ? Will the larger size K&N's improve the situation even more ?

As always, your comments are much appreciated.

Never Satisfied
Dino

Dino Zappi

Dino,
Try this website http://www.hotelling.com/mgb7.htm . I think it is what you are looking for. Sorry, I don't know enough about the mechanics of air flow through the carbs to answer your other questions. Maybe someone else will chime in.
Paul
Paul S. Canup

Hey Paul,

Thanks for your quick response, the attachment is exactly what I was looking for and am in the process of ordering a pair of K&N's from Jeff Zorn at Little British Car Company.

Maybe I can now go from 0 to 60 in 4.7 secs. ? Vroom...

Much obliged, Dino
Dino Zappi

Dino,
Would really like to hear about the results. Have been thinking about doing that mod also.

John
J.T. Bamford

Perhaps a little more cam, more compression, port/polish like I've done.
Then way less disappointment.

Don't forget the timing. Not just base/idle timing, but full advance. Full advance should be before 4000 rpm as well. If not, then it will need recurving.

Grassroots Motorsports did a rubber bumper 'B' last issue. They had a stock, [ I think 1979.] With twin HIF's, Peco header and exhaust, Pertonix ignitor, K&N tapered filters with the stubby volocity stacks inside. And the gains from 30 degrees total to 35 degrees was about 1-2 HP.
They tried various things, but came up with a boost of 59 HP to 64 HP at the wheels on a dyno.
I did not see any figures for the switch from the SZ to the twin HIF's.
Dwight McCullough

Some of us noticed a slight increase in power - either from anticipation or less restricted airflow. ;-) Regardless, the size disc you need is 5" Dia. As noted at Roger Hotelling's site, I used those tough plastic wall protectors they sell at Lowe's and Home Despot to keep door knobs from puncturing plasterboard. I have had mine on my car now for a few years and they still work just fine, haven't warped, and seal well. Just follow Roger's directions and you should also have good results. Probably the biggest advantage I noted was the vastly improved access to the SU carb adjustments. And, they don't look too bad either! Several other folks on this BBS have chosen other materials, even paint can lids, and other "found", but suitable objects. Just use your imagination as you wander around the hardware store.
Bob Muenchausen

... and I've had mine on since I heard about Bob's! I've got a feeling the "boosted performance" is all in my head, but what the heck, they sound better too! Hearing that intake sucking down all that air makes it feel like you're going faster. :) (I really do think throttle response is better)

Roger Hotelling
'69 Rdstr
Roger Hotelling

Count me in there too! I did mine a couple of years ago and am very happy with them. The plastic wall protectors haven't warped nor lost any paint.

Robert
Robert Rushing

Hi Dino

I am planning the same project and found suitable wall protector discs at our local Home Depot. Roger Hotelling's web page gives good construction details.

Barry
73B
B.J. Quartermaine

One vote here for the quart sized paint can lids. I like the look of the finely polished tin, so used those.

BTW, for tubing to use as spacers on the bolts, I went to the section for toilet hardware. One of the stiff metal standpipes was exactly the right inside diameter. They're made of chrome plated copper, so when done, they look like car parts, not toilet plumbing.
Matt Kulka

I turned a couple aluminum plates on an engine lathe a couple years ago. Left a smaller diameter standing about .25 inch that fits the ID of the air filter element. Drill two holes in each plate to use the stock "rubber" sealing washers, spacers and bolts. Then used the stock filter plates( the ones that bolt up between the filter and carb opening. These are my "velocity stacks" I was told by a gentleman who used to race MGB's that he used these stock plates on his wide open carbs( no filters) while racing. They stablize the air entering the carb. Ny-lock nuts on the end of the filter bolts complete the job. This works well with either the stock paper filters or K&N's. If you can get the use of a lathe that is.
DB Bush

I did the same modification to the stock replacement K&N filters on my 67 BGT. I kept the stock base plate and found a pair of turned aluminum discs at MOON EYES hot rod parts. They are like mini wheel discs that were used for salt flat and dry lakes racers. The unique thing I did was use a 6 in. length of 5/16" UNF "all-thread" screwed to the stock backing plates with a nut to hold the base plate to the carb throat. I drilled 2 holes in the discs to match the stock canisters. I slide the filters over the bolts and use chrome acorn nuts to hold it all together. I polished the discs to match the polished dashpots and it looks better than expected.

When I need to get at the carbs I quickly remove 4 nuts and slide the filters off. Everything else stays in place. I have some 1/4 turn Dzus fasteners that I will try to make work next.
Chris Butler

I just bought a set of K&Ns that fit right over and cinch onto the stock snub stacks w/o going to the trouble of fabricating. The only modification I performed was to use flat head 5/16 screws and countersink the screws into the snub stacks. My biggest problem was deciding if I wanted chrome ends or rubber ones. The base diameter needed is 3.5" I can go back to the stock filter housing at any time - but the Q is why?
M Landskroner

This thread was discussed between 06/05/2003 and 08/05/2003

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