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MG MGB Technical - K&N 'Bob' Filter follow up

As mentioned earlier, the installation of K&N "Bob" filters to my 73B (standard engine with twin HIF SU's and ABD needles) resulted in a weak mixture giving reduced 'seat of the pants' acceleration compared to the original arangement. Reference to the WinSu program identified AAA needles as having the same initial diameter but with a richer mid range. Installation of these needles this weekend, and readjustment of the carbs per Haynes', have brought the engine to life again with plenty of low end torque.

My rationale was that at idle, the freer flowing K&N's make little difference to the mixture so the use of a needle with the same initial diameter would give the required improvement under acceration since the carb mixture is set up under idle conditions.

Had some nice comments on the "Bob" filters - BobM should apply for royaltires!

BarryQ
73B
B.J. Quartermaine

That's royalties!
B.J. Quartermaine

The tires would be good too, Barry, but thank you! Enjoy the filter benefits and thanks to Roger Hotelling for putting up a webpage on how to do it - my fame would not be so great without it! ;-)

I suspect the poor bloke who came up with the K&N aluminum plate (essentially the same idea, only earlier on) probably hates my getting the recognition ~ probably hurts *his* royalties. C'est la vie.
Bob Muenchausen

WinSu program? I must have fallen asleep when the instructor went over that! Where is this available? I have the same problems with K&Ns causing a lean condition.
Paul Briggs

The little application that Barry alludes to is found at this ftp site: ftp://ftp.team.net/sol/suneedle.exe , Paul. You can easily download it to a floppy or on to your hardrive or some other media.

We all owe somebody at teamnet a big vote of thanks for this one.
Bob Muenchausen

I also claim the fame for actually naming them "Bob Filters"!! When I put up the web pages, I needed to name them something and wanted to give Bob full credit for their intricate design! :) In the full spirit of this BBS and our MG Family, I wanted to give Bob full credit for his ingenuity and the considerable reasearch, design and testing! Bob, I think maybe you should publish a paper on them, followed by application for international patent! :)

Roger Hotelling
Roger Hotelling

I'm glad there isn't any royalities - otherwise, I'd owe Bob some money!

Robert
Robert Rushing

Robert,
Put that money back into NAMGBR!!!! with my blessing! In fact anyone so inclined can make a "Bob Filter" donation to NAMGBR, I am sure they would appreciate it! :-)
Bob Muenchausen

Bob, now you're just trying to move to the top of my favorite people list...

Robert
Robert Rushing

OK, now I've got a little problem. I've bought the K&N filters but I can't find proper diameter plates to install them. I've checked Lowes home improvement store and several others with no success. B.J., where did you find yours in Canada? Canadian Tire?

For those interested, I got mine online for a great price at:-

https://www.ajusa.com/cgi-bin/knfilters/start?kn

E-2400 for $24.97 ea. plus free shipping. Paypal accepted.

All the usual bla-bla about no commercial interests, etc.
Derek Nicholson

Derek

I got my discs from Home Hardware - they are sold as door (wall) protectors.

Good luck,

BarryQ
73B
B.J. Quartermaine

Derek, a tad more specifically, they are sold as hard plastic discs to protect plasterboard walls from door knobs. Usually, they are packed singly on a cardboard sheet with a clear plasitc cover and are either white or beige. FYI
Bob Muenchausen

Bob, I tried Lowes in NY. The only ones they had were too small in diameter. BJ, I'll see if I can find a Home Hardware near me. Thanks.
Derek Nicholson

Okay, I missed something here- What the heck is a Bob filter? Never heard reference to it before. Pardon my ignorance- this is a bona-fide question
Greg Fast

Greg

It's a cult thing (just kidding) - go to the following link for full construction details.

http://www.hotelling.com/mgb6.htm

Regards,

BarryQ
73B
B.J. Quartermaine

Sorry guys but the bob filters are not new. 20 years ago did the same thing buy cuting the sides off a old set of "Cooper Cans" so why not call them Ray Filters.

Ray
Ray Gordon

Derek, You can also pick up the end caps up at Home Depot.
SteveO

Ray,
I never claimed originality, one look at the K&N aluminum end plate in the Moss catalog was enough for anyone to steal the idea if they were thinking. They just stuck with my name because I made mention of my doing as you did (different materials, but same principle) and described how to duplicate my efforts on this BBS. Hell, the idea has been out there, I bet for probably as long as people have been installing K&N filters on MGBs - certainly a lot longer time than my dabbling with door knob protectors or your cutting off the sides of your Cooper's cans. The idea belongs to the MG world, call them what you will.
Bob Muenchausen

Well, I've tried Home Hardware and they've got exactly the same as Lowes. Same type wall protectors as suggested by others, but way too small. About 3" diameter. Now that I think of it, why the heck would you need a wall protector, unless to spread the inpact forces over a larger area.

I wandered the aisles, filter in hand, and came up with 2 possibilities. There was a 5 " diameter galvanized steel cap for HVAC ducting. The cylindrical part would have to be removed. The other was a domed fitting in the lighting department with a single hole in the middle made to sit flat on the ceiling with a threaded rod through the middle for a hanging light fixture. Available painted white or brass finish or ornately patterned if you fancy a baroque look under the hood. A little inprovising would be needed to use the single center hole, but I think I'll give it a try.

I'll report back if I succeed and could email photos to someone with a website for posting. Sorry, I've a digital camera but no website.

TTFN
Derek Nicholson

Been there, done that. Got a pair of light fixture caps for US$4.00. Got 1 installed/prototyped already. Two holes drilled, 15 seconds with the angle grinder and it's together. A little bit of fiddling with seals and it'll be finished. Unfortunately the K&N filters I've bought a 100 miles away, so for now it'll run with standard paper elements. Cap removes with plastic thumbscrew for now. Maybe I'll change to a stainless Allen bolt.

If anyone has somewhere to post a few pictures, I can email them later this evening.

TTFN, I'm off to do the second filter.

Derek Nicholson

Bob

I know I was just given you all a hard time!

It's a good idea, but I would like to find a way to get cool air to the filter not just hot air from the exhaust header.

Ray
Ray Gordon

Ray,
I have been amazed at the ingenuity of so many people who have done this mod, some after reading my posting, many others a long time before. The part that I get the biggest kick out of is variety of things people have chosen to use for those end plates! Look at Derek's, for example.

My plastic wall protectors were just supposed to be an interim test of the idea, to be replaced with something "more substantial", but, well, the cheap plastic discs are still there and still doing just fine. But folks have made up really nifty machined end plates, used paint can lids, coffee can lids, Octagonal blocks of wood routered with the MG logo, and among others, a really clever clear acrylic plastic end plate (looked like it must be at least 3/8" thick) so you can see all the wonderful filtering and air flow action! The possibilities are limitless, and it is fun! I expect someone to send me a photo of their Neon lighted installation next - what do you wanna bet? ;-)

As for cool air to the carbs, I have often wondered why MG did not do with the B as they had with the MGA by having a cool air duct running from behind the grille through the radiator baffle and dumping over the carbs. There are a variety of existing materials we could use in a variety of shapes that would do this same job, but for some reason I have not seen anyone do this - yet, except on a few cars with V-8s or other non-standard engines in them. The only reason I can think of why the factory only put a smallish hole in the radiator baffle was perhaps to enhance the ram effect of incoming air through the radiator. I think that too efficient air flow past the baffle into the engine compartment could weaken the pressure differential between the ram air ahead of the baffle and the engine space behind it. Perhaps a bit of airdam design could help compensate for the extra flow to the carbs and still maintain the right ratio of incoming vs. outgoing air through the radiator.

Another possibility might be to add some louvers to the inside fender wells? Perhaps a few on the carb side might change the pattern of circulation so as to pull cooler air towards them in a steady flow, rather than allowing a stagnation in that area?

There are several ways of getting cooler air in there without a lot of major sheetmetal alteration but it is tough to know which is the most effective without some way of monitoring what each one does. A truly serious effort could do it with computer modelling and/or sensor mapping. A good project for someone with the right resources.

Bob Muenchausen

Bob-
I solved the problem of hot air in the engine compartment by getting the exhaust manifold Jet-Hot coated.

Just to spice things up a bit, you can get the wall protectors in polished brass if you like! We slapped a set on a friend's MG and the results were very pretty indeed.
Steve S.

Steve, you solution is a good one. Drag racer friends have done that and seem pleased with the results. I wonder if you have compared that to the insulating wrap treatment? That too is supposed to work.

For myself, the cool air issue has less to do with carb percolation than it does with air density into the carbs. If I had the extra bucks, I would like to play with TWM Induction's air box, but my budget says a compromise is more likely. ;-)
Bob Muenchausen

Although I fairly live at Home Depot, I couldn't find anything to use for the base, not even in polished brass. Considered re-fabbing the old, nevre to be used again Coopers, then had a better thought ( as Dustin Hoffman's uncle recommended in the Graduate 30 years ago): PLASTICs. Last year, I had the tach and speedo glass reproduced out of glass clear plexi on all the cars, and I recall paying not-much ( I tend to remember those rare instances more over the common scrousle). I patterned the 2 base bottoms, and a one-piece top ( like Moss offers for $100) and the guys cutting them and drilling them as we speak. I'm paying $28 for the lot, out of 3/16 plexi, and considering the short stub stack, now that it can be seen! Also, maybe a glueon of a couple of 77-80 steering motif for max-spiff. Can anyone recommend a thinner high-flow filter for the SU's, after cutting down the spacers, and notching the heat shield, soas to use this rig on the RB?
vem myers

Ack! I just had time to catch up on this thread. I fear I may need to do some work on my web site in the way of updating a name. I see that another "originator" of the Bob Filter has come forth. Do I need to rename them (on just my web site of course) Ray-Bob Filters? Will the unsuspecting think they originated in the South U.S. with a name like Ray-Bob? Maybe they should be Bobby Ray Filters? That makes it sound like they came off of some NASCAR though. Help me...

Roger Hotelling
http://www.hotelling.com/mgb6.htm
(Home of the Bob Filter description)
Roger Hotelling

Just call 'em "Using K&N Filters on MGBs", that works for me (maybe Ray too), and it matters little who or how it came about. It is the idea that matters, the rest is irrelavant.
Bob Muenchausen

How about "Filter Covers by Muenchausen Proxy" or "Baron Von Filter Covers"?

Nah, "Bob Filters" works for me!

Robert
Robert Rushing

Hay!! way not just call them R&B Filter Covers, Ya that it R&B and sing the Blues as you get down and put them on ;-) It dose not reaily matter like Bob said "it matters little who or how it came about. It is the idea that matters, the rest is irrelavant."

Ray;-)
Ray Gordon

Hey, I like that, Ray! Love R&B too!
Bob Muenchausen

This thread seems to have taken off on a tangent. I have just seen an article that identifies the potential need for needle changes after fitting less restrictive air filters - see under the heading 'Pancake Air Cleaners' in the following link
http://www.mgcars.org.uk/cgi-bin/gen5?runprog=mgoc&p=emg/basic4.html I came across this link via the very usefull Teglerizer SU links site at
http://www.teglerizer.com/sucarbs/


This may be common knowledge however just spreading the word.

BarryQ
73B
B.J. Quartermaine

This thread was discussed between 13/07/2003 and 24/07/2003

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