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MG MGB Technical - Emission Equipment Removal

I am looking to remove the emissions control system from my 71 MGB GT engine. Currently it isn't even hooked up by the belt to the air pump, so it is doing nothing more than cluttering up the engine bay from what I can tell. I think I have identified all of the pieces that can be removed, but I want to know if I can just plug the openings that are formed in other pieces of equipment by removing things like the gulp valve hosing? Also, the charcoal canister that takes the vapor from the carbs, can I remove that and plumb in a catch can and a return line to the tank, or is there more to consider there?
D. T. Barnes

Hi,

I think there is an article by John Twist in Lindsay Porter's book on mgb restoration regarding removal of American anti-smog equipment. Unfortunately I can only say 'I think' because my book is out on loan. It might be worth contacting John Twist.

FWIW

Peter
P L Hills

Anything connected to the air pump should be pluged, i/e vacuum lines and the air ports in the cylinder head. Either leave the charcoal canister as is or remove it, vent the carb bowls to the air, plug the return line to the tank and install a vented gas cap.
John H

Peter's right - there are step by step instructions in Porter's book - page 307 in mine, under the heading "'De-Toxing' US Cars".
John English

I always thought that should be termed "re-toxing," since you're making the car more toxic, not less. ;-)

I disagree with removing the emissions gear -- it won't give you any noticeable performance change and will make the car emit more pollution. I'm selfish -- I don't want to breathe your pollution. I also want to return the favor, so in exchange for you keeping your car clean, I maintain my emissions equipment on my car intact and functioning. I think that it's inconsiderate and irresponsible not to!

Keep the evaporative emissions equipment -- it probably does the most to reduce emissions and has absolutely, positively, no effect on performance.

The gulp valve does not affect performance, because in normal operation it does nothing -- it's closed. It's only on overrun (deceleration) that it does anything. When the throttle snaps closed on engine overrun, there is high manifold vacuum, which opens the valve and admits air into the manifold, thereby reducing vacuum to prevent the mixture from going rich.

The function of the air injection pump is debatable -- it pumps fresh air into the exhaust stream, which either: A. allows any unburned HCs in the exhaust to complete their combustion, or B. simply dilutes the exhaust so it appears cleaner. Either way, it won't affect performance enough that you can tell by the seat of the pants.

My car was missing all its emissions gear when I got it. I acquired & installed it all, and I think it actually runs better with than it did without....

HTH!
Rob Edwards

OK, thanks for all of the info. I understand that the emissions control may only bring small, if any, performance gains to a car. I also kow that the emissions control that BL placed on these cars was a hodge podge effort and kind of an afterthought, I have read many debates on exactly how effective it really is. I agree that I don't want to pollute the environment. As I work through the engine I will make a decision then on whether I want to remove it, or keep it and make it work.
D. T. Barnes

Rob, emmision controls on those years cars did about as much as spitting on a forest fire.
Anyone not agree?
I'd like to hear more.
The added weight of this 'stuff' plus the drag on the engine could result in poorer fuel mileage alone is enought o remove it.

Hey Rob, I have a perfectly good air pump for a 'B'. How mucha give me for it?

D.T. Barnes, yes, they were all hodgepodege in those years.
I personally use a Pertonix ignition, and other items that improve both power and good mileage, and it probably does as much as the O.E. did.

SF
Dwight
DCM McCullough

DT. Keep the charcoal cannister. It takes nothing away from the performance, you do not have to replumb the fuel system and having the carb overflow (vent) lines connected to it is a better solution to fumes than the earlier system.

My 68 does not have an air pump and still passes emissions testing on a yearly basis. Removing the pump and the air rail is relatively easy. The holes in the cylinder head are best filled using a set screw of about 1/2" length. (Do not remember the size and thread, but if you cannot find it in the archives I can measure it for you.)

You would want to plug the intake manifold where the line from the gulp valve goes into it.

You do not want to remove the PCV system which, I believe, was a line from the front tappet cover to the two carbs on your model.

As with some of the others, I am not too sure how much good the emissions controls on these engines do. My daughter's 77 came to us without a cat on it and the gulp valve failed, causing a lean miss condition. I plugged the line to the gulp valve and, without a cat, the car passes the annual emissions testing requirements. A properly tuned, well maintained engine is a clean running engine.

Les
Les Bengtson

Dwight,
Though you said that in jest, I'm interested. I need one for my C -- I understand that they're the same as the B pumps, or close enough. I'll have a closer look at the frozen one on the C and see if it looks like yours will work. What year is it from?
Rob Edwards

Rob...the air pumps on the MGC are NOT the same as the MGB/midget.....I'll snap a photo of mine and e-mail it to you....it is a much larger unit and uses a completely different filter...

FWIW..

rick
rick ingram

I say get rid of all the damn air injection crap. All it was for in the first place was to satisfy U.S. Govt. airheads. I got rid of the stuff on my 69 MGB and it runs WAY better. The gulp valve was of a notoriously bad design and these are almost always flaky.

Plug your injector holes with 7/16 " 20 fine thread bolts 3/4 " long.
T.R. Fisher

Rob, I do have one, and it is late model, and spins freely.
email me.

Rob Edwards, North Carolina, USA, rob@deletethis.mgcarz.com; http://www.mgcarz.com
Dwight,
Though you said that in jest, I'm interested. I need one for my C -- I understand that they're the same as the B pumps, or close enough. I'll have a closer look at the frozen one on the C and see if it looks like yours will work. What year is it from?

SF
Dwight

P.S. Oops, that email won't work. Try this---

dwight@bmcautos.com
DCM McCullough

Once again thanks to everyone for their advice. I will do some more investigating/tinkering once I get this Weber installed and have the engine set back up properly. Right now I have all of the equipment, it is just not hooked to the belt. Will let you know.
D. T. Barnes

My failing memory tells me that the air pumps were made by Delco Remy. If they are chances are they were also used in volume on GM cars as I doubt they would have tooled up a special for the UK manufactures. You might want to look into it.
John H

Rob,I got new carbon vanes/brushes from John Twist,along with the bearing to do a rebuild.Contact him and see if he has anymore to rebuild yours. Dont lose the curved springs !!Later,Rich O
Rich Osterhout

John,I think that they were made in Japan,and were the same as the ones on all the Datsun's,Rich O
Rich Osterhout

>Dont lose the curved springs !!

Yeah, I hear they're hard to come by! That's ok, though, because I've got a pair here that I finally got out of a frozen pump. Seems like I was supposed to send them to someone once I got them out..... ;-)

I dug out the C and had a look -- the pumps are different. It may be possible to use a B pump, but not without modification....
Rob Edwards

good for you...get rid of it all...it's a total bunch of crap and a major drain on engine power. US ""Federalized"" cars ended up at 63bhp. No wonder so few late 70s US cars had overdrive...they couldn't muster the torque to use it!! But then we also had the 55mph idiocy ...."saves fuel and speed kills"...apparently only in America. Actually...crap driving kills regardless of speed or emissions. Get that B back to 95-100 bhp...it'll go faster and use LESS fuel, not more.
P J KELLY

PJ. Please be aware that, during the life of the MGB, the ratings for "horse power" changed their interpretation. Thus, as is my understanding, what was once "horse power" measured on the engine became "horse power" measured at the wheels. The differences in the various horse power readings are as much due to this as to the various add-on emissions devices.

My 79 MGB, purchased as a Personal Export Delivery car (no cat installed, but all the emissions controls in place) would cruise, quite comfortably, on the German Autobahns at 85 mph in overdrive. It would, also, go over 100 mph, as I found out, as a paniced Father, when my daugher demonstrated a fever of 105 deg F. I only slowed down enough that the Security Police, at the gate to the base, could recognise the flashing hazzard lights and my Officer's decal on the car.

Many years later, that daughter learned to drive on a 77 MGB which she still owns and in which her new husband will drive her away from the wedding using wedding cars sevenoaks in. (I drove my wife away in the MGB I had purchased when we were both stationed in Germany.)

My daugher's car, which my future son-in-law will be driving, has an engine rebuilt by myself, using a Peter Burgess "Econo-Tune" cylinder head. This car, fully, meets all of the require Arizona emissions standards. It will also perform as well as my 68 GT does.

Thus, the required emissions control systems do, to a VERY limited amount affect performance. But, the driver makes more of a difference than the modifications to the engine ever did.

Thus, those who believe that keeping the emissions controls on their cars is a good thing have my vote. Spend the money on a two day course at the Bondurant School. Set up a race between someone who is a Bondurant graduate, racing an "emissions restricted" car against the average owner with an "de-toxed" car.

I will wager $100 on the Bondurant trained driver in the emissions equipped car against the untrained driver in the "de-toxed" car.

If someone wants to keep their car "green", they have my approval. I would do the same myself, but, I would ask that I be allowed to meet the original, as required emissions testing standards, and might switch to a set of twin SU carbs. (The emissions standards never changed--5.0% CO, plus or minus .5%. The later vehicles were required to meet these standards with the air pump disconnected and the various hoses plugged. But, the same basic standard from the 1968 through 1980 period.)

Les
Les Bengtson

PJ, we may have to ban you to the 'flame wars' thread.


'P J KELLY, New York, USA, pjkbrit1@netscape.net
good for you...get rid of it all...it's a total bunch of crap and a major drain on engine power. US ""Federalized"" cars ended up at 63bhp. No wonder so few late 70s US cars had overdrive...they couldn't muster the torque to use it!! But then we also had the 55mph idiocy ...."saves fuel and speed kills"...apparently only in America. Actually...crap driving kills regardless of speed or emissions. Get that B back to 95-100 bhp...it'll go faster and use LESS fuel, not more.'

But LOL just kiddin', I agree!
What I would do, if I had the $$$$ is install a Electromotive fuel injection sysem on my '77, and betcha the CO level would be down around 1.5%
SF
Dwight
dwight@bmcautos.com
P.S. I looked in the Moss catalog, and no listing for a 'C' air pump.
DCM McCullough

Speaking in my professional role as an environmental scientist who did his senior research on "auto emission control" over 30 years ago, during the height of the switch to emissions controls in the US, biggest improvement in 'detoxifying' our emissions came from the elimination of lead from gasoline, thereby requiring catalytic convertors. I think the most important thing we all can do is keep our cars well tuned. As we are all hobbyists, I would venture to guess that the majority seek to have our cars tuned to the best of our ability, as opposed to the average person who is not as concerned with performance as we might be. Therefore, good tuning usually equals the optimum performance for an engine, which will yield the best use of fuel, which now has a significant impact on the environment. For my own vehicle, a '72 came to me with the equipment stripped out by the PO,I cleaned up the sloppy job he did and have sought to maintain the machine to the best of my ability, which should yield the lowest emissions and best performance possible. The reinstallation of an air pump and associated gear would not nearly have the same positive impact as the elimination of lead and a well tuned engine. So we are all running with less toxic emissions than we were back in 1972, whether we intend to or not.
Joe

interesting Les....my kick back against emissions regs on older cars is because here in New York, the regulations are just ridiculous. I have an 85 Saab Turbo...it gets 29 mpg on a bad day. NY State have been LOWERING the limits retrospectively for NOX and CO to levels many 80s cars were never designed to meet. Think about it...lowering limits on cars that represent a tiny fraction of the total car stock and often do far fewer miles than newer cars...yet these cars MUST be regulated. Every year I have to fight the State to get my emissions waiver through Bear in mind my car only JUST fails every time and given the limits of 5 years ago would have been an easy pass...perhaps they'd prefer I drive my other car..a Land Rover every day? And what really pisses me off is choking behind every 1950s technology school bus or v8 carburettored gas guzzling contractor truck that is exempt from the same standards. Back to MGBs...my 78 MGB was smogged....and was pathetically underpowered....now it has twin SUs, and a proper distributor and so drives the way it was designed....ie; normally...it also uses LESS gas than before. I am considering adding an aftermarket cat to the Peco system I have....but after other recent automotive legal incidents here in NY I'm a little inclined to tell them to go stuff themselves. ( Got fined $155.00 for RETURNING from a State Inspection in my MGB last year...tester simply hadn't had time that day even though I'd left the car the whole day...went to the Kangaroo Court who simply took the money...reminiscent of summary justice in teh 1700s in Britain...I thought this country was founded on other principles!!!!!)
What a rant....feel better...thanks!
P J KELLY

If you choose to remove all that emissions stuff, my e-mail address is here and I'd be interested. I have an '80 LE that was stripped of all the emissions and can't possibly (even on a good day downhill) perform close to what my '70 B was capable of fully outfitted with emission controls. I have several gulp and anti-backfire valves (those failed occasionally), but don't have the air rail. I have a pump (still have the '70 engine), but it is siezed. I also will pull the SUs from my '70 engine and install this summer in place of the Weber DGV that someone installed on the '80. Since all is ported and tuned for emissions, I feel more comfortable reinstalling the emission system rather than figuring out all the "voodoo" it takes to tune an emission free system.

I drove my '70 MGB daily from 1972 to 1987 and remember the mid-70s craze to remove all the emissions. I knew my local MGB dealer mechanics and all of them warned against removing them so I didn't.

The '70 B engines were rated at just over 90 horse even with emissions, so I agree with many that other changes (lower compression, and single carb instead of dual) were the real reason for declining horsepower.
Rick Penland

Interesting points and information from everyone. Thank you for the stories and the continuing flood of information. I am sure this can be a continuing debate, and I am sure if we all keep our cars (no matter the emissions control or level of performance) properly tuned, we are doing a great service both to keeping these cars alive and keeping the environment in decent shape, unfortunately there are plenty of other things leading to the decline of the environment...but this is a car forum, so we can keep it gear head related. Thanks all.
D. T. Barnes

Rick...those early emissions systems really were the voodoo....air injection/gulp valves/air pump....catalyst positioned to maximize the risk of fire...I mean...really!!!!LOL Imagine...years of bugger all emissions 'saved' from our tiny little 1800cc engines only to see a flood of really noxious fumes when the whole bloody car goes up in flames!
P J KELLY

PJ. They have been lowering the allowable emissions standards here in Arizona also. There are completely different testing procedures in the Pima County (Tucson) area than what is used in Maricopa County (Phoenix) area. Tucson does a test at idle. Phoenix area requires a test at both idle and simulated cruising speeds (on a roller set).

Here in Arizona, the cost of re-registering your car is based on the "value" of the car with cars loosing value each year until you hit a base line figure. I pay $20 per year to register my MGs. My wife pays about $400 to register her Mini Cooper. Thus, the State has a vested interest in removing older cars from the road because older cars do not pay the high fees newer cars do. Plus, everytime a dealer sells a car, the State and various local governments get sales tax revenue.

There have been various studies done to indicate that emissions testing does nothing to improve the environment and costs a great deal to operate. The cost-benefit analysis is that doing away with the emissions testing would result in no degradation of the environmental quality, but would save money due to decreased operation costs. This is not being done because the federal government requires that we have emissions testing in place if we are to receive federal highway funds.

Les
Les Bengtson

Les...yep it's all down to money!!! Here in NY registration fees are the same regardless of age or vehicle value...and that dyno test is just so inaccurate...last year I went to 4 differnet staions with my Saab within days of each other....the results varied hugely. It's just patently unfair.
P J KELLY

DT,
After all the posts, if you still need any info on detoxing the B, let me know and I'll send the Twist information. But, it sounds like all this has been covered already so have fun. You'll notice the difference in performance.
Randy
1977 MGB
randy olson

Ok, I gotta answer this one,

'Joe, Holden, MA
Speaking in my professional role as an environmental scientist who did his senior research on "auto emission control" over 30 years ago, during the height of the switch to emissions controls in the US, biggest improvement in 'detoxifying' our emissions came from the elimination of lead from gasoline, thereby requiring catalytic convertors'

Joe, sorry but you have it backwards.
Catalytic converters will melt and plug up with the use of leaded fuels!

The cat's were installed to further reduce emisions, and they are the one thing that does it better than any other device that is bolted on, versus bult into a engine design.
That being said, lead was added to improve octane ratings. And it also caused a buildup of carbon deposits and could block or even burn valves.
But lead will destroy cat's.


Unleaded fuel is waaaay better.

SF
Dwight
dwight@bmcautos.com


DCM McCullough

NY State is difficult to deal with when it comes to cars and emissions, etc. Do what I did - register the car in a "friendly" state. Hassle all gone :>{D

cheers
Gary :>{D
79 MGB
gnhansen

DCM: I believe I made a slight grammatical mistake, what I meant was once lead was removed from gasoline,it "allowed" the use of cats, not "required" them. I apologize for my confused wording.
Joe

S'ok Joe.

SF
Dwight
dwight@bmcautos.com
DCM McCullough

This thread was discussed between 15/05/2006 and 20/05/2006

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