I know this is a very cheeky first post but I will post a hello thread at a later date!

The wifes '81 343 has failed it's MOT on emissions, the carb was massively overfuelling so despite being played with for hours it still ran very rich! I'm led to believe it's a Weber 32DIR (correct me if I'm wrong). Does anybody have a known good one for sale? I've only been able to find one and that's on ebay in Italy and is quite pricey!

Any help would be much appreciated!

Welcome stemo,

If your carb is grossly over fuelling there are a limited range of possible reasons almost all of which are solveable. Before simply changing the unit for an "unknown" it might be better (and more economical) to do a little investigating of the existing carb (and yes on a UK spec. B14 it will be a Weber 32DIR variant.

Possibles :- (in no particular order)

Blocked fuel pump return line leading to high fuel pressure.
Incorrectly set carb float height.
Punctured carb float.
Loose carb top bolts allowing fuel to "wick" over the f/chamber lip.
Internal crack in carb body.
Displaced (fallen out) primary barrel main jet.
Severe blockage of air inlet/air cleaner.
Gross maladjustment of CO screw - Note this will ONLY affect mixture at idle speed not at higher revs.
Gross maladjustment of choke mechanism.
Seized or partially seized choke flap/s.

If you are able yourself, or know of a "mechanic" the 32 DIR is a relatively simple carburettor to recondition and rebuild kits are fairly easy to obtain for about £35 or so.

In extremis - a replacement unit - but it will still need to be checked and correctly set up and adjusted - and may well have problems of it's own!

Hope this helps - if you need more info just ask.

Mac.

As far as I am aware 81 shouldnt be tested for emission, only visual? could try the mot at a different station.

Evoman wrote:As far as I am aware 81 shouldnt be tested for emission, only visual? could try the mot at a different station.

Chris, I don't know what the significance is of 1981 in your mind?? It's only a visual for vehicles first used before 1st August 1975. (exhibit "A")

macplaxton wrote:

Evoman wrote:As far as I am aware 81 shouldnt be tested for emission, only visual? could try the mot at a different station.

Chris, I don't know what the significance is of 1981 in your mind?? It's only a visual for vehicles first used before 1st August 1975. (exhibit "A")

ah, i knew it was certain age, 81 is alittle newer than 75 thank you

Mac, many thanks for the reply, I'll get the carb off and start having a proper poke around and see just exactly what's what in there and if need be order a rebuild kit, never rebuilt a carb but I'm sure I can give it a damned good shot! Thanks.

My MOT man is a safe bet, been a family friend for years and looks after my Carlton very well at MOT times - not in a dodgy way, just a genuine test!

Thanks guys - seems like a good forum to be a part of already

Hi mate.
My bannana is 1981 and it has to be tested for omissions.
Love to see some pictures of the car.
Welcome to the fold
Cheers Mark.

" Gross maladjustment of CO screw - Note this will ONLY affect mixture at idle speed not at higher revs. "

What do you mean? Adjusting the mixture screw will only adjust idle fuel? Not the overall rpm range injection of fuel?

Yes, the 32 Dir mixture screw ONLY affects the mixture passing through the idle bypass passages. In a fixed jet/fixed choke design the overall mixture is determined by the size and shape of the choke (carb barrel) tubes and the calibration of the main jets. The effect an overall mixture change you change the size of the jet orifii.

Hopefully by now you will have received my article which will fully explain the principles in the "theory" section.

It is a very common misunderstanding that the mixture screw changes the overall mixture range - not so.

If however you take the case of CD type carburettors (Stomberg, Skinners Union, DVG) then the mixture adjustment truly does affect the full range. In such carbs the fuel is metered, not by a fixed jet, but by a tapered needle moving within a jet assembly producing the equivalent of a fixed main jet with a variable orifice.

Simple really.

Mac.

So, i was wrong all this time haha I really thought it was affecting all the rpm range, not just the idle lol :p

About the article, not yet, should be here in the next days, sometimes they are lazy with the shipping.

Thanks

Ruben,

Article was posted @15.35 on 03/01/13.

Give it a few more days and if it doesn't turn up I'll have a moan at the Post Office and send you another one.

Mac.

mac wrote:Ruben,

Article was posted @15.35 on 03/01/13.

Give it a few more days and if it doesn't turn up I'll have a moan at the Post Office and send you another one.

Mac.

Sometimes i have items from Uk like in 2 or 3 days, other times it takes a couple of days extra, depends.
I'll give you a touch when i receive it.

Thanks

Hey guys,

Just wanted to post back (taken a while I know!) Managed to get hold of a brand new carb for a very good price and proved to be the quicker option in interests of getting the car back on the road asap. Will however be rebuilding the old one when I get a moment!

Thanks for all the help.

Hi mate.
Pictures please. Everybody here loves drooling over pictures
Cheers Mark.

To some of us here a picture on a brand new carburettor is pure porn!

Mac.