New Member, emissions question

[Missouri722]

Glad to find this forum. I'm soon to be the owner of a 1980 MGB Limited Edition. Seller has my cashier's check and I have the title. Just waiting for the car mover to pick it up and get it here.

I've owned several MGs (MGAs, MGBs, MBC), but sold my last one 16 years ago. The one I am buying has a Weber DGV and has been "defederalized", as we used to say. One thing I remember from my early days with Bs was that you didn't remove the emissions controls unless you changed the cylinder head and such.

Many did it and had fast Bs --- for a few weeks or months, then they had performance problems. The heads are ported and machined to accomodate emissions and usually clogged up with carbon eventually.

Hope I have searched properly and don't bore you with a subject that has been addressed already, but what do the many experienced B owners here feel about this issue?

 

[adam90009]

Use higher octaine petrol and it will be just fine, I've seen pictures to back that up. or jsut use seafoam everyonce in a while to clear it out.

 

[Frazier]

Don't know about an '80 with a Weber, but my experience with a '71 with SU's, the head has not been an issue. I also recommend premium fuel.

Frazier

 

[Missouri722]

Thankfully, I have an entire '70 engine in my shop complete with SUs. Probably will replace the Weber with SUs, add an Ansa extractor, but "refederalize" the engine. I'll check some other sites about how to do. Aware that the '80 has brake booster and included EGR that wasn't on the '70. Have all the components except the smog pump is siezed up. Probably not hard to find. Want to drive the car. Not just a collector's car.

 

[Missouri722]

Thanks for the replies. Got the LE from the car transporter Friday. One of the best looking I've ever seen --- and the poorest running B I've ever been in. Has a Weber DGV that won't run at all under 2000 rpm (shuts down every time you brake) and runs very rough when it runs at all. Had to nurse the car home. Don't know Webers, but will get into that soon. Still would like to hear from someone about defederalizing these engines. The ports on the head are plugged on this one, but the anti-runon valve is still in place with one outlet sawed off and some sort of glue stuffed in it. How do you defederalize, do you gut absolutely everything?

 

[Bruce74B]

I don't know about the newer ones, but my 74 B is done the same way yours sounds like...including the anti-runon valve which is still connected to the charcoal canister and the plugged manifold ports. The air pump and rails as well as the gulp valve and related plumbing has been removed, but everything else is still stock. She has run fine like that for several years ;-)Sounds like you will have to start with the carbs and will solve most of your problems.

Bruce

 

[John S Farrington]

My MGB is a 78 and has been defederalized years ago with nothing but great results. I have converted it to dual SUs and solid state ignitions (at present it is a Pertronic). I always use 89 octane gasoline. It also is fed gas by a rotary fuel pump. The MG engine is very indifferent to modifications such as this with great results. Let me know if you need any other advice.

 

[Steve]

I am seriously thinking of de-federalising my 1980, but would like to buy SUs for it before I start.

 

[tony barnhill]

I have several sets of buildable HS-4's & HIF-4's for sale...I say 'buildable' because any carb that's been sitting on a shelf dry for some time needs to be rebuilt - even if they were rebuilt just before they were put on the shelf (IMHO)

 

[Steve]

Wise advice Tony. I'll keep your selection in mind, but for the time being finances rather preclude any such activity. /ubbthreads/images/graemlins/frown.gif

 

[WJM]

Hi All. I have a 72 MGB which I have just bought. It is running like a tractor or worse. The canister and valve you have been talking about is not there. The out lets on the carbs have been joined together with rubber pipe. I have not been able to set carbs due to this. Im not sure which carbs is fitted but the fuel bowl is under the slide chamber. Does any one have a diagram of how it should be or is there some way of bypassing something to make it run better. Regards John.

 

[Missouri722]

Finished travelling and home for a few days and taking a few minutes to look into this '80 LE. First, found the "nusiance" oil leak. Owner stated on E-Bay it wasn't major, just a "nuisance" --- blown head gasket, but he wasn't mechanical enough to figure it out. For you novices to the world of "B"s --- never, ever waste money on anything less than a copper head gasket. Been there, done that, and have the oil-soaked t-shirts from pulling and replacing them.

I'm sure that contributes to the engine operation problems. Got a head gasket on the way from Victoria British along with a rebuild kit for the Weber. Maybe I can smooth this car out long enough to pass state inspection. I'm amazed at the moment that the car hauler got it up the ramp to transport it from North Carolina to Missouri.

Got a set of HS4s on the engine in the shop. Of course, probably have spiders living in them as big as the throats and need complete rebuild. Save that conversion for later and try to make the Weber actually run.

Two questions left: (1) do you fellows saw off the one side of the anti-run off valve and plug it up (return to manifold outlet)? This one has that Rube Goldberg feature and (2) I think it's OK, but when I pull this head and replace the gasket, I mind find a crack. In that event, I have a '70 head that can go back in its place. Don't have the specs, but my '70 was an "H" high compression engine. Will the head pose any problems, or was the difference mostly the 3 compression rings instead of 2?

Yeah, I should know all this, but been 20 years since I sold my last B and left the Haynes manual in it when I sold it.

 

[Bruce74B]

WJM...your 72 didn't have an anti-runon or gas cannister.

MO- most people cut off the forward nipple, seal it, and/or cover the opening with black electrictian's tape...from what I have seen anyhow.

Bruce /ubbthreads/images/graemlins/driving.gif

 

[NutmegCT]

fwiw guys - here's two sets of de-fed tips:

https://www.mgclub.org/bbs/messages/4065.html

https://www.universitymotorsltd.com/qa/display.php/55

In the second set, note John Twist's reference to the Lindsay Porter chapter on "de-toxing".

On my 76B with Weber DGAV, all the emissions gadgets were pulled except the ELC canister. The anti-run on valve has the small nipple plugged. I ran canister hoses per JDW's suggestions:

https://www.mgbexperience.com/service/weber-hose.html

Tom

 

[Missouri722]

Thanks for the information on the small nipple from the anti-run on valve. I've been unable to see it in photos of engines, but apparently it is eliminated and plugged in most instances. Eventually, I'll probably refederalize it completely and go back to the SUs. But for now, just want to make it run.

The last B that I drove for many years, a '70, was kept federalized and in good operation. It would snap you back in the seats in any gear, never backfired (of course, had to renew anti backfire valve on occasion), idled very smooth and would "bury" the speedometer easily. I realize the LE's compression ratio will never allow that level of performance, but sounds like defederalizing is a sort of "voodoo". But that's the way it came to me and don't have the time until late winter to embark on a project to put it all back on.

 

[CDNMGBguy]

For what it is worth my 80 is de-smogged i.e. without air pump and gulp valve, but still with the Z-S Carb. It runs fine, and even better now that I've switched to electronic ignition. I agree, for a good reference see the Lyndsay Porter book, and my B does pass the emission testing here in Vancouver, Canada - better than my old EFI, catylytic Honda Civic (1989) did. Most air pumps were removed because they seized, and only reduced emissions a further 10% at best.

 

[Missouri722]

Thanks for all the advise. Replaced the cylinder head gasket, rebuilt and tuned the Weber, set the valves, replaced and routed missing emission hoses and it runs smooth and performs well.

Passed Missouri inspection, but that bears no relationship to what its true emissions output is --- Missouri doesn't even look, just checks for exhaust leaks.