Is there such thing as a worn carburettor?

"Adam R" wrote

The jets wear out but can be replaced.

Would a replacement engine come with its

No.

Yes, they wear out.

Probably not. I had a 4 yr old Cavalier that was great up to 60-70mph, then it would start stuttering, and almost dying.Up to that speed there was no problem at all. It turned out to be a worn carburettor, the pivot pins for the various flaps had worn, allowing more air to be sucked in to the carb, thus weakening the mixture.It could be repaired by rebushing it at around £60, or a new Weber carb could be had for £130ish, so to save the hassle, a new carb was fitted, and it ran perfect afterwards. Alan.

And what symptoms would you get with worn carb jets? That wouldnt explain loss of power when going up an incline would it? How much do jets tend to cost?

The jets car wear, along with a needle, if it has a needle fitted.

It is possible that the plunger could wear and score the barrel of the carb, but we're talking mega-mileage or moto-x bikes....

Artie

"Adam R" wrote

Well, that's when you are putting most load on the carb so yes, it could. Are there any other symptoms?

How much do

What make/model car are we talking about?

You can also get wear around the pinion points where the butterfly valve sits, leading to an air leak and resulting in excessive revs at idle. Only ever seen this on bike carbs though.

If it starts off with power and then gradually drops off in power on the same throttle setting I'd think about fuel starvation. Have you swapped the filters and checked the float chamber is filling OK?

Butterfly shafts wear, as do the bores for the shaft in the carb body. Other wearing parts can usually be easily replaced, but once the bearing holes in the casting itself have worn, the body needs to be bushed or replaced.

Would a replacement engine come with its

IME replacement engines come without any ancilliary parts, such as carbs, starters, water pumps etc. Mike.

Depending on the design, jets can wear out, needles can wear out, pistons can wear out, diaphragms can wear out, throttle pumps can wear, and spindles on butterfly vales (or the holes they revolve in in the body) can wear out!

So there's quite a bit of potential here. What type of carb are they?

Yes, they certainly wear out. There are lots of moving parts, even in fixed-choke designs. A typical problem is that air starts to leak round the butterfly spindle as the bushings wear, which upsets the mixture.

The message from Adam R contains these words:

Yes, both and no. At least, that no assumes you're not just taking an engine from a donor in the scrappy.

The message from Chris Street contains these words:

You've not had many SU carbs then!

"Guy King" wrote

Trivia note, SU stands for "Skinners' Union" and the company is related to Lilley & Skinner, who made and sold shoes.

Their experience in leatherworking led them to develop leather diaphrams for early carburettors.

Right, I'll take me anorak off now.......

"Chris Street" wrote

Have you swapped the

Fuel filter would be my very first port of call for poor fuel delivery problems too.

The message from "Knight Of The Road" contains these words:

I'll stick to my Freeman Hardy and Willis downdraughts, I reckon.

The only car I possessed with a carb was a metro 1300, which IIRC had an SU but that was the only thing that never seemed to go wrong on it.

Bike wise most of them had SU's apart from some ancient British efforts with slide types - once had the crap scared out of me when the slide jammed fully open.

What commonly happens is that the holes the spindles sit in go oval or the jets get larger bores due to wear. As well as that, the diaphragms can perish.

A replacement engine won't come with a carb.

Yes.

If it's a fixed jet carb it's likely to need replacement. An SU can usually be adjusted to some extent.

No - unless it's a complete secondhand one. And even then not always.