It's leaking from the black plastic bit below the brass thingy, and the car stinks of fuel. I've been putting this off for a while now, as I know very little about carbs, and I'm not keen to tinker.
Has anybody changed this little pipe/jet? and is it straightforward......
It's easy enough - in fact you could just try re-fitting the one you have. It has (or should have!) a little rubber seal in there - the end of the pipe pushes through the seal and then the nut compresses the rubber down onto the pipe holding it in place. Disconnect the fuel pump - and run the engine till it dies - then slacken the nut and carefully pull the pipe out and inspect the seal. Then re-assemble, reconnect the pump and see if it's any better. Of course - the pipe itself could be knackered - maybe as well to get a spare in stock before fiddling with it - but it is pretty dangerous (and expensive) if it's leaking fuel at the moment!
If it's leaking from the float end then it can almost certainly be re-seated or have a new seal fitted, but if it's leaking from the jet end then really it's best to just fit a new one. It can be hard to tell where the leak is as the petrol nicely sticks to the pipe till gravity overcomes it..
All you need is a cross headed screwdriver and 7/16 spanner to remove it anyway, and they're pretty cheap (just under/ over a tenner I think)
Probably a very fine crack/ split, starting at the hole the choke lever screws into. I've had a couple of SUs go there. It really is very easy to replace, the trickiest bit being getting the seal into the float chamber nice and leak proof (easier with the carb off, a bit of a pain with it on but quite doable).
It won't hurt to have a nice new jet anyway, as the original could well be rather worn by now
Given the hole is likely to be worn so the jet is slightly larger than it should be, you almost certainly will - But it's a single HS carb, not all that tricky to get it back to right!
Easy way to get an SU nearly spot on - Get the engine nice and warm and wind the adjuster up till the engine is running very poorly. Then wind it down till the engine's as rough again. Count how many flats from one point to the other, the "sweet spot" will be half way between the two
You'll be far better off with a non-leaking brand new non-worn jet even if it does mean a slight tweak to get the mixture spot on.
Also, be careful when removing/ refitting the jet as you don't want to damage the needle. You can pop the dashpot assembly off if you're at all worried about it, otherwise undo the float end of the pipe first, so you simply lower the jet away, and then the opposite when putting it back together.
Might be worth fitting a new jet bearing/ carrier while you're at it (if you have the cash to spare), another really simple job with the carb on the bench, but possible (with some swearing) with it on the car
Setting the mixture on an SU is dead easy - they even provide a little 'lift' pin for you test it! As above - set it till it idles nicely, then lift the little pin about 1/4" - if it speeds up it's too rich, if it slows down it's too weak. Re-adjust and try again. But to be honest - it's not exactly a critical setting!
