MGB Zenith Stromberg and a Cat on an earlier model car?

[Vardaman]

First post.

I just bought a '66 that's incomplete. I'm no stranger to MGs, so I know my way around the naughty bits of an SU, but I'm more of a tree-hugger now, so I'd like to have a car that doesn't pollute quite as much as my other 3 MGs did. I'm also trying to save some money on this build.

Going rate for a pair of SU HS4s with linkages is around $350. I've found a few downdraft Webers in the $300 range. I'm not ready to go Megasquirt, since it involves too much scrounging and fabrication. And I just stumbled across a complete '77 single Zenith with the exhaust manifold and a cat installed for $120. Probably because they're what everyone else is getting rid of when they install Webers. I don't need a really fast car, and my recollection is that even my fastest MG still wasn't a fast car, so I'm wondering if these might be a good option for me.

Is this something I can put on a stock '66 engine?
Does it need a smog pump and the associated air fittings?
Will the performance be terrible?
Would I lose a lot of resale value by going with something non-original?
Are there other more modern carbs (or even FI throttle bodies) that can be installed on this manifold?
Would it actually help with the emissions?

Any help with this is greatly appreciated.

 

[Mickey Richaud]

First, welcome to BCF!

Your '66 was engineered to run with the dual SU's; can't go wrong with sticking with them.

 

[Vardaman]

Point taken, but I'd rather have something that pollutes less. Would the single Zenith-Stromberg accomplish this, or were there other changes in the later engines that would preclude the use of the single Zenith-Stromberg?

 

[JPSmit]

I would stick with the SU's. I understand the environmental aspect of it but, the ZS was designed to run with all the other smog stuff - air pump/ evap canister/ air rail etc. etc. On my Midget it was genuinely unhappy without them (they were off the car when I bought it). I think a properly setup set of SU's will be about as clean as any engine of that vintage can expect to be. And don't forget that the fact of owning a 1966 car and still using it MASSIVELY offsets the carbon footprint of building a new car.

In terms of a cat - I run a Harley Muffler on my Midget - it has a catalytic converter built in (or so I am assured) - I got mine cheap from a harley dealer as it was a take off.

If you are that concerned about emissions, you could maybe swap in a Miata engine for the joy of an MGB with the efficiency and environmental compliance of a modern car.

Welcome and regardless this seems like and awesome project!

OH and please contact JohnGone who needs a ZS to get his B compliant with California emissions. Let him buy the ZS! His conversation is here: > MGB - Help getting my 1980 MGB to pass CA smog test <

 

[JohnGone]

I would stick with the SU's. I understand the environmental aspect of it but, the ZS was designed to run with all the other smog stuff - air pump/ evap canister/ air rail etc. etc. On my Midget it was genuinely unhappy without them (they were off the car when I bought it). I think a properly setup set of SU's will be about as clean as any engine of that vintage can expect to be. And don't forget that the fact of owning a 1966 car and still using it MASSIVELY offsets the carbon footprint of building a new car.

In terms of a cat - I run a Harley Muffler on my Midget - it has a catalytic converter built in (or so I am assured) - I got mine cheap from a harley dealer as it was a take off.

If you are that concerned about emissions, you could maybe swap in a Miata engine for the joy of an MGB with the efficiency and environmental compliance of a modern car.

Welcome and regardless this seems like and awesome project!

OH and please contact JohnGone who needs a ZS to get his B compliant with California emissions. Let him buy the ZS! His conversation is here: > MGB - Help getting my 1980 MGB to pass CA smog test <

Thanks. I will contact him.

 

[Grantura_MKI]

There are many problems with what you want to accomplish. If the car is on the original motor, the head will not have ports for the air rail to start of with.
There are many issues with the factory set up of the cat and manifold.
Fit a side draft Weber and go.

 

[JohnGone]

First post.

I just bought a '66 that's incomplete. I'm no stranger to MGs, so I know my way around the naughty bits of an SU, but I'm more of a tree-hugger now, so I'd like to have a car that doesn't pollute quite as much as my other 3 MGs did. I'm also trying to save some money on this build.

Going rate for a pair of SU HS4s with linkages is around $350. I've found a few downdraft Webers in the $300 range. I'm not ready to go Megasquirt, since it involves too much scrounging and fabrication. And I just stumbled across a complete '77 single Zenith with the exhaust manifold and a cat installed for $120. Probably because they're what everyone else is getting rid of when they install Webers. I don't need a really fast car, and my recollection is that even my fastest MG still wasn't a fast car, so I'm wondering if these might be a good option for me.

Is this something I can put on a stock '66 engine?
Does it need a smog pump and the associated air fittings?
Will the performance be terrible?
Would I lose a lot of resale value by going with something non-original?
Are there other more modern carbs (or even FI throttle bodies) that can be installed on this manifold?
Would it actually help with the emissions?

Any help with this is greatly appreciated.

Hi Vardaman, JohnGone here. I could use that set up. Have you scoped it out? I understand cracks in the manifold are the key problem. You can pm me at (jcremer(at)gmail.com)

 

[Vardaman]

Hi Vardaman, JohnGone here. I could use that set up. Have you scoped it out? I understand cracks in the manifold are the key problem. You can pm me at (jcremer(at)gmail.com)

It's in Oregon, so I haven't been able to look at it. I'm in Washington.

I'll send you the link, since it doesn't sound as though it will work on mine.

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[JohnGone]

Thanks. I will keep you posted.

 

[DrEntropy]

Point taken, but I'd rather have something that pollutes less. Would the single Zenith-Stromberg accomplish this, or were there other changes in the later engines that would preclude the use of the single Zenith-Stromberg?

Welcome to the Forum.

The "sweet spot" of MGB production was '66~'67, IMHO. 5-main engines, no degradation of the power output ( a whopping(!) 99HP). Putting that engine into original running spec's at this point would have about the same effect on the environment as would dropping another grain of sand on Hermosa Beach. A pair of SU's would be less problematic than all other options, in that it was how the thing was designed as a unit. As Grantura suggests, a side-draft 40mm Weber would be next-best option. All downdraft conversions have setup issues, some without solution. The Zed-S induction & emissions stuff was a concoction thrown together by Leyland as afterthought, so as to continue selling cars to the US market, and an abomination for those of us who worked in service shops to keep them compliant.

And one more '66 MGB running original induction has less deleterious effect on the planet than the army of Z3's running around now, anyway.

 

[JohnGone]

Hello Dr.Entropy, I appreciate your valuable thoughts here. It is a dilemma for sure.

I agree 100%. No doubt in my mind that of the (now) three MGBs I've owned ('67, '77 & now '80) the one I wish I'd never sold is the '67 -- By far. And I agree with you on the pollution aspect: My 3000 miles/year in weekend cruising up and down the coast on CA Hwy 1 is not going to have a jot of an effect on the environment. In fact, this car came to me from Norwalk, CT with all of the pollution gear removed, a Weber carb, and dual exhausts pumping out that classic throaty note. I'd love nothing better than to just upgrade and improve on this little gem from this point.

(BTW: I've driven the car a bit and had it in the garage over a temp. cardboard floor covering for a few days and not one drop of oil so far. Could it really be an original odometer reading of 32,000 mi? The former owner says so, and he's already got my money and can tell the truth.)

I wonder what combinations of carb(s) you mention would pass CA Smog testing? They seem to insist on the British Leyland Rube Goldberg scheme in total. All or nothing.

Like our Canadian friend mentioned yesterday: When is CA DMV going to back off on these requirements that mandate cars be fitted with equipment almost no longer available? Absurd and wasteful in it's own way, but until they do I am forced to try my best to comply. I guess.

 

[Grantura_MKI]

There was a time when the Terminator was gov that older vehicles didn’t need to be smog tested.
I have had customers sell there pride and joy because of the DMV. California does not want your old car in the state, period.

 

[YakkoWarner]

Thats one of the things I never understood - the goal is to minimize emissions. You would think any car that passes the actual tailpipe sniff on or better than spec should be fine, but its not. With modern injection systems and electronic engine controls you could make that engine run much cleaner than it did on day 1 out of the factory. Requiring the original equipment seems counterproductive to the goal if aftermaret equipment can do better. The pass/no-pass should be on the result of the exhaust gas analysis, not what equipment is used to produce the result.

 

[Mickey Richaud]

Thats one of the things I never understood - the goal is to minimize emissions. You would think any car that passes the actual tailpipe sniff on or better than spec should be fine, but its not. With modern injection systems and electronic engine controls you could make that engine run much cleaner than it did on day 1 out of the factory. Requiring the original equipment seems counterproductive to the goal if aftermaret equipment can do better. The pass/no-pass should be on the result of the exhaust gas analysis, not what equipment is used to produce the result.

Agreed, but how much in the way of add-ons would be required to make the modern bits work as they're supposed to on 60+ year-old lumps? I'm thinking sensors everywhere, control modules, etc., etc.

It would be interesting to see a true side-by-side comparison of a properly tuned and dialed-in early model B and one with all the required bits to do the FI and electronic conversion. Wonder if there's truly an appreciable difference...

 

[Vardaman]

Good news. Sourced an absolutely filthy but complete set of SU H4s on Ebay for $100. Got to get the buffing wheel spinning!!

 

[JohnGone]

I wonder to whom we could adress that 'good question'? I worked for the State of California for most of my career (Dir. Video Services, State Compensation Insurance Fund, Ret.). The DMV have elected overseers who respond to constituent's needs. Hmmm.

 

[Mickey Richaud]

Good news. Sourced an absolutely filthy but complete set of SU H4s on Ebay for $100. Got to get the buffing wheel spinning!!

Great! For rebuild kits, Joe Curto is your guy: > British Superior | Vintage Carburetor Parts and Restoration | United States <

 

[JohnGone]

I believe the original equipment was a single Zenith - Stromberg, correct? It sounds like OE or nothing with testers.

 

[JohnGone]

I believe the original equipment was a single Zenith - Stromberg, correct? It sounds like OE or nothing with testers.

Whoops! Please ignore this last post. I was responding to an early post in this thread. My bad.

 

[Vardaman]

And it's a miss!! Didn't notice the mounting flanges on the used pair that I bought, which are not at the proper MGB angle, but are straight up and down (pictured below). Probably from an MGA. Still worth $100. And I've found that my FIL who has owned lots of British cars has a pair of HIFs that he'll send to me.