new carbs....

[phurn]

It's high time I got a new carb, the current one has a lot of play in the linkages and what not, anyway can anyone make any recommendations for a good replacement, cost being the main issue, any performance increase second.

I've never really messed with carb before.. is be a lot happier messing with fuel injection tbh, so any advise would be great.

[bmcecosse]

Either overhaul the one you have - or just get a better version from ebay - or the 'wanted' section here. Make sure it has the little brass inlet pipe on the side - for sucking away the horrid crankcase fumes.........

[aupickup]

second that
refurb the one you have , you can get a refurb kit from su burlen or any morris minor specialist

[phurn]

Having never messed with a carb before I reckon ill buy a second hand one and a refurb that, then drop it on and keep my current as a good spare for emergencies. That way i can drop it straight on with no messing! Which is usefully since its my daily! How much are these kits then and what does it consist of?

[chrisryder]

i believe the kits come with a new spindle, and bushes for them. i think you just press the old bushes out of your carb and press the new ones in. logic dictates that you would have to ream them after fitting, i'm not sure how you overcome that, maybe the bushes dont compress much. kits come with a new jet (but not a new needle due to different applications) and possibly a new throttle disc.

i have a feeling they're about £20 - £25.

once you take a carb apart, you'll have a much better understanding of how they work. i find that's the case with most things though!

if you do come to strip one down, take loads of pictures as you go to help with reassembly.

if you do go looking for a spare carb to work on, do try to find one with the brass breather tube on, i think bmc mentioned that already.

[phurn]

Awesome however my throttle linkage has a lot of sideways movement in it, does the kit contain the relevant parts to correct this?

[chrisd87]

I recently rebuilt my carb (standard HS2). It's a pretty straightforward task, but as has been suggested it's a good idea to rebuild a spare carb off the car, just in case you meet with any difficulties. I used the SU/Burlen rebuild kit from Bull Motif, which has everything you need (including a new spindle, bushes, jet, throttle disc, float valve, etc). I also fitted a new needle at the same time which doesn't come with the kit. The cost was about £35 all in.

When purchasing a carb to rebuild, make sure you get one of the right type. Not sure what year your car is but later ones have an inlet on the side of the carb for the crankcase breather - if yours does, make sure you get a carb that also does.

Fortunately I didn't need to replace the bushes on the carb I rebuilt, as once fitted the new spindle had no play in it. To fit them, I think you have to drill out the carb body slightly, then press the new bushes in. This strikes me as best done on a pillar drill as the alignment would need to be fairly exact.

[Alec]

Hello Phurn,

there are a variety of kits, from a basic gasket set to an overhaul kit.
If going for the latter, the throttle disc needs some adjustment before finally tightening the screws. The aim is to get the best seal in the carburettor choke (note the disc fits one way only) by fitting the disc with the screws slack and pressing the throttle shaft hard closed and the disc should centralise. Tighten the screws and split them.

Alec

[Neil MG]

It seems everyone is dodging your question!
If the spindle bushes are worn you will not be able to tune the carburetter properly as it will draw in air, it may also have an irregular tickover as the butterfly valve may not always seat in the same position. You need a competent machine shop to fit and ream the standard bushes so that they are in exact alignment. For home DIY there is a reaming tool that can be used with an oversize spindle, but that tool costs about £140 plus VAT.
Consequently, when rebuilding carbs, most people just fit new spindles and as a result most used carbs. have heavily worn bushes!

[phurn]

That's exactly what I'm experiencing! Sometimes tick over is quite high, then I blip the throttle and it comes right down!

So if I were to buy a second hand carb and refurb it odds are it would be exactly the same unless I buy a ludicrously expensive tool, or took it to a machine shop?

[Alec]

Hello Phurn,

your original post seemed to indicate play in the linkage,

did you mean the throttle spindle? If that is the case, it's worth seeing where the wear is, as it's often the case that with a hard material and a soft bearing the hard material wears much more. (As Chris found out)
If the body is excessively worn, then it is a workshop job but it is an easy procedure, as the tolerances are fairly high (By engineering standards).

Alec

[bmcecosse]

Make sure the sticking throttle is not caused by a frayed cable/weak spring/cable too tight/cable needing greased! I understand the throttle bushes can be fitted by careful use of a NEW drill bit - but I have never done the job. As others have suggested - a new throttle shaft will take up at least half of the wear anyway and is possibly worth doing. It also depends how much 'idling' your engine does - if very little, then just put up with any slight air leak at idling - I have heard of folks fitting O rings on the shaft against the body to minimise any air that can be sucked in there - again I have never done this.

[phurn]

Checked all that, it all returns to its original positions nicely, but sometimes tick over is high, other times normal. When its high, if I jiggle the linkage left and right Abit it settles down again.

I can live with it, but it is annoying and I would like it fixed tbh.

I live in the midlands and go to uni in Birmingham ergo lots of traffic and lots of idling!

[bmcecosse]

The design of the carb install on some Minors leaves a lot to be desired - where the cable pulls on one arm of the spindle, and the spring pulls back on the other arm - designed to maximise wear....... Would be better if the spring directly opposed the cable - maybe worth trying that if your's is of the earlier design?