Fitted new carb today......

[Jojax]

The old one was never right, so decided to buy a brand new one. Couldn't find the exact SU carb, though.
My old one was AU 8450. The new one is AUD 13. The seller assured me it would be fine with my 950 engine, and even sold me the "appropriate needle" for my engine. Well, got it fitted, and now not a peep at start up. Nothing.....not even a splutter. Could I be overlooking something obvious, or is this carb no use for my motor?

EDIT.....just noticed a small but steady trickle of petrol dripping from the black plastic bit at the bottom of the mixture adjustment.....eek!

[philthehill]

The AUD13 SU Carb is the one specified for the 1098cc Minor.
That does not mean that it will not work on a 950cc Minor engine so long as you have the appropriate needle and it is set up correctly.
Does it have the breather connection (brass tube sticking out of the carb body?). If it has try blanking it off to start and then sort the breathing system out later when running. A non breather HS2 AUD13 carb is available if required.
Where did you get the number AU8450 from? The reason I ask is that it is not recognised on the Burlen ebsite.
See the Burlen web site for all details relating to SU carbs http://sucarb.co.uk
There are details relating to Minor carbs and the setting up of the carb.

[chesney]

Is the jet centered correctly, piston rising and falling nicely and mixture in the right ballpark?

[bmcecosse]

As above from Phil - ANY SU carb of that size will work provided the float bowl is sitting vertically (is it?) - and a suitable needle is fitted. If in doubt, fit the needle from your old carb, although it is likely to be worn.. The drip is hopeless - obviously - but at least it shows petrol is getting there. Is it from the little tube where it connects to the float bowl? In which case tighten the gland slightly. Or from the jet assembly ? In which case tighten gently. And as above - the piston must be free to rise and fall, and stick a blob of blue tac in the breather tube for now. It is a much better breathing system - so you need to connect it to the rocker cover breather pipe in due course.

[Jojax]

The number AUC 8450 is stamped into the carb body. Just to the right of that is a number 18, inside a small circle.
The little brass breather thingy is present on both carbs. It was blocked off on the old, and I've blocked it off on the new.
The piston seems to rise and fall ok.
I did manage to get it started with the new carb. I took out the "recommended replacement" needle and tried it with the new original 1098 one. Car ran for a while, and I remembered I'd forgot to top up the damper.
Switched off, topped up damper (with modern, semi-synthetic oil) and the bugger refused to start again.

[bmcecosse]

Now it's AUC xxxx - before it was just AU xxxx The needle has virtually no influence on 'starting' - since almost all needles are same dimensions at the root. Make sure the piston is moving - are you using/is the choke connected ok?

[Jojax]

Sorry about the typo.....lol.
I think the chokes connected ok. Maybe a little tighter than it was before when pulling on from inside the car.
I've decided to call it a day now.....been at it for hours. so frustrating, I've even managed to draw blood from my finger. lol.
Looks like I'll need to find a carb man to sort this out.

Here's what it looks like.......

[Jojax]

A wee note....on the two occasions that it has started, it's run well for a time. I've switched off to replenish the dashpot both times.....and it refuses to start again.

[kennatt]

are you saying you have had to refill the dashpot twice??

[Ufudu]

Perhaps it has already been mentioned above^^:

Is the mixture set approximately correct? I purchased a new HS2 carb and it arrived with the mixture screw fully wound up (closed?) so no fuel was getting through.

[Jojax]

Not sure. If anything, it was wound down too far. Car is running now, I think I made every basic error today. Never fitted a carb before, I was ok till it came time to attach the cables. Think I had them both too tight....throttle slightly on, so the tick over screw was having no effect, and the choke too tight as well.
However, I live to fight another day. What I've got in place just now is a hybrid. Body of the new carb, and the piston/needle of the old one.
Thanks for the help everyone. Think I'll be using this site a lot. Lol.

[Chipper]

Check that the piston rises and falls with no sticking; use your finger to raise it then drop it - you should hear a nice thunk as it hits the jet bridge.

[Jojax]

With regards to the needle. How far do you push it into the piston before tightening with the grub screw?
Incidentally, the grub screw on the new carb is made of soft metal, (brass coloured) and looks like it wouldn't need much encouragement to strip the slot if it was to become stuck. Grub screw on the old carb is far better.

[mike.perry]

The shoulder of the needle should be level with the bottom of the piston. You only need enough oil to the top of the piston with the damper in. Any more will be drawn in to the engine.
Are you sure that is a 948 engine? Looks like a 1098 to me.
Any photos of the inside of the car?

[philthehill]

The needle should be pushed into the piston so that the bottom on the boss is level with the bottom of the piston. If the other grub screw is better use it.
The number you quoted originally is the casting number and is not the number of the carb. The number of the carb is usually on a tag attached to the float chamber lid screw as in your current carb.
All the details for setting and adjusting the carb are on the Burlen web site see details in my post above.

[Jojax]

I was told by the dealer that the engine was a 948.....log book says 998.
The tag on the old carb float bowl was unreadable. The stamp on the dizzy is unreadable too......

[Chipper]

A 948cc engine number will begin 9... while a 1098cc one will begin 10...

Dizzy is usually fairly easy to read - it's on a flat area on the body; try scrubbing it with a fine wire brush. It should say 25D4 and a 5-digit part number, from which you can verify if it's correct for your engine:

http://www.mmoc.org.uk/viewtopic.php?f=11&t=4266

[mike.perry]

We have already decided that it is a DM 2 dizzy

[Jojax]

Thanks, everyone.