Smog Equipment & it's removal. Why?

vping · Jun 19, 2007

Why would you remove it and what do you need to do differently when working on it after it has been removed?
I saw a 74B and the air rail was removed & capped. I am not sure what else was part of this system and what esle was removed but how does it improve/effect performance?

Steve · Jun 19, 2007

It does improve performance. I was speaking to a guy who has a '79, and a previous owner had taken off the emissions equipment and installed SUs. The car still passed the emissions test when the new owner took it before getting his collector plates, so I don't know what the standard is.

The air pump and lots of the tubing are all connected with the smog equipment, in fact I have seen articles on removing it all and getting the car set up to run without it.

Nunyas · Jun 19, 2007

With an MGB, the biggest gains (in power) come from being able to switch to twin SU's and being able to use a much more efficient intake manifold design. Straight pipes from the carb to the intake ports on the head are much better at breathing/developing power than the single ZS manifold that makes 2 to 3 90-deg bends before going into the head. That and being able to use much more efficient exhaust manifolds/headers.

Another benefit of removing the emissions equipment on MGBs (I suspect it's much the same for other vintage cars as well), is it greatly reduces the amount of trouble shooting you need to do when the car starts running odd. Malfunctioning mechanical emissions parts (in my experience) tend to make the car run leaner. So, when ever I feel a difference in the way my car behaves I always check all of the emissions valves before I start looking at the ignition or carb mixture.

That last paragraph also explains why I always ask people about their emissions equipment when they post about problems with their 1974 and up MGB's.

martx-5 · Jun 19, 2007

Re: Smog Equipment & it's removal. Why?

It all depends on what smog equipment is being removed. The Air Injection Reaction system you are talking about usually has an air pump to force more oxygen into the exhaust to further burn any unburned gases. The pump requires horsepower to turn it. Not alot, but it does sap the engine a little.

BTW, in New York State, vehicles that are less than two model years old, or more than 25 model years old are exempt from emissions testing. You only get a safety inspection. So rip everything off that you don't want that may cause you grief. Leave the PCV system on however, that's beneficial to the engine. /bcforum/images/%%GRAEMLIN_URL%%/cheers.gif

William · Jun 20, 2007

My old '76 Midget had the air pump, and a PO had removed the pump and simply put a threaded pipe cap on the end of the manifold. Sadly I managed to bust off the end of the manifold somehow, and that made the car run really weird till I sealed the end off again. Dad came home one night with a used replacement pump and manifold because at the time there were rumblings that I would need the full emissions setup if I wanted to pass the emissions check. Never got around to needing it and I think the pump and all the bits we had got tossed when I got rid of the car.

I think the B we have now is supposed to have an air injection pump as well, but its long gone.

-Wm.

PAUL161 · Jun 21, 2007

Unless you intend on RACING your car, the benefits of removing the smog equipment from any duel SU car is nil. This 72 runs as sweet as you could ever want. Smooth idle, great response on the throttle and will run 75 mph all day long and gets around 30 mpg. All equipment on this engine is original including the dizzy with points. If you remove equipment from the car because you don't want to maintain it, why in the h**l do you have the car in the first place? Sorry if I'm too blunt, but my concern for "OUR" planet and my 60+ years makes me that way.
My 72. And however small it may help, it all works the way it was intended too. PJ

DrEntropy · Jun 21, 2007

Re: Smog Equipment & it's removal. Why?

makes me wanna run right out an' find a smog pump & rail...

...'cept I'd need to drill a few holes in me head first. /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

vping · Jun 21, 2007

As I said, the car already had it removed. I figured that if the car was engineered with it, why take it off and figure out how to keep it running.

DrEntropy · Jun 21, 2007

Vince, the pump was originally fitted as Leyland's clever dodge to meet tailpipe emissions standards so they could continue US sales... All it did was thin out the noxious oxides by introducing an amount of unsullied air apres-combustion. If it's gone, it would be more trouble than value to reinstall it, IMO.

vping · Jun 21, 2007

Here is what it looks like as is. If it's running now I don't think it is going back in.

Don_Neff · Jun 21, 2007

That "air pump" in your photo is actually your Alternator - you don't want to eliminate that.

Take a look at the photo posted by Paul161, a few messages prior to yours. You'll see the air pump mounted above his alternator driven by a second belt.

DrEntropy · Jun 21, 2007

Re: Smog Equipment & it's removal. Why?

Don, he's already said it (pump and rail) was removed. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

vping · Jun 21, 2007

Don_Neff said:
That "air pump" in your photo is actually your Alternator - you don't want to eliminate that.

Oops!

GregW · Jun 21, 2007

Re: Smog Equipment & it's removal. Why?

It wouldn’t surprise me if your old air pump was on a motorcycle somewhere. I’ve heard they used ‘em as superchargers back in the day.

Basil · Jun 21, 2007

Re: Smog Equipment & it's removal. Why?

Personal choice I suspect.

PS: Beautiful motor you have there!

vping · Jun 22, 2007

PAUL161 said:
Unless you intend on RACING your car, the benefits of removing the smog equipment from any duel SU car is nil. This 72 runs as sweet as you could ever want. Smooth idle, great response on the throttle and will run 75 mph all day long and gets around 30 mpg. All equipment on this engine is original including the dizzy with points. If you remove equipment from the car because you don't want to maintain it, why in the h**l do you have the car in the first place? Sorry if I'm too blunt, but my concern for "OUR" planet and my 60+ years makes me that way.
My 72. And however small it may help, it all works the way it was intended too. PJ

I'd love to be able to get 30 MPG. What's the secret?

DrEntropy · Jun 22, 2007

A rev limiter and feather-foot the gas pedal. /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

vping · Jun 22, 2007

So Doc, what your'e saying is, Fat chance if I like to "Drive" these cars.

Nunyas · Jun 22, 2007

Well, I wouldn't put it past our cars to get that kind of mileage on the highways/interstates. The best I've managed to day was 25MPG (HWY) with the single carb ZS equipped '76, but I think that is probably as close to the best I'll be able to get with the manifold design on my car. All those 90deg bends tend to spoil the efficiency of the 1.8L air pump we like to call an engine.

rick_ingram · Jun 22, 2007

Nunyas said:
Well, I wouldn't put it past our cars to get that kind of mileage on the highways/interstates. The best I've managed to day was 25MPG (HWY) with the single carb ZS equipped '76, but I think that is probably as close to the best I'll be able to get with the manifold design on my car. All those 90deg bends tend to spoil the efficiency of the 1.8L air pump we like to call an engine.

The best I ever got in an MG was in 1992 with my 1978 MGB Tourer on the way to Peterborough, Ontario, Canada for MG '92.

I ran a single HIF6 (precursor to the HIF44 now on the market) from an Austin Marina on the stock MGB manifold. I got 32 mpg running with the top down at about 70mph with a passenger (my wife) and our "supplies" for the week.

Smog Equipment & it's removal. Why?

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