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!
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.
88 5door Redline 1.7 52k - 19 XC60 Momentum Pro D4 AWD 17k
1950 pair of legs that don't work very well.
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
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.
88 5door Redline 1.7 52k - 19 XC60 Momentum Pro D4 AWD 17k
1950 pair of legs that don't work very well.
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!
88 Volvo 340DL Diesel
