What's this?

Doz · Post by **Doz** » Sun May 06, 2007 6:34 pm

Hi All,

This is my carb. If you look closely at the picture I've ringed a mystery component... it has a vac hose at the front, and this operates some sort of bellows which moves a lever in and out which disappears in the direction of the choke/ throttle mech. Can't find a description or pic in Haynes. What's it's purpose in life?

I have a problem with a massive flat spot at small amounts of throttle, which seems lessened if I screw this in. If I screw the screw out, the tickover picks up , and the flat spot gets nasty. I hate screwing something without knowing what I'm doing

.

Tickover is steady as a rock, and past the flat spot everything's groovy. Ignition leads, cap and arm are less than 2,000 miles old.

Stewart (oily!) · Post by **Stewart (oily!)** » Sun May 06, 2007 6:40 pm

Looks like some kind of accelerator pump, normally used to give a squirt of fuel into the inlet when you mash the accelerator, why not take the filter off the top and operate the throttle and see whether theres fuel squirting in? the thumbscrew probably regulates how much fuel goes in. the linkage will be spring loaded so that it does not operate when the throttle is opened slowly, gosh I love diesels

Stewart

DavidRutherford · Post by **DavidRutherford** » Sun May 06, 2007 6:41 pm

I *think* that's a choke corrector. Its purpose in life is to back the choke off a bit if you put your foot down a bit hard while the choke flap is closed.

Have you had the jets out of your carb? Mid range flat-spotting is often caused by blocked emulsion tubes.. (that's assuming your carb has emulsion tubes... what type and style is it?

Doz · Post by **Doz** » Sun May 06, 2007 6:42 pm

Yeah, I though that ... but why vac operated? The accelerator pump usually comes off a cam attached to the throttle, but I may be wrong. Which I had access to a rolling road, then I could actually look at what the gas is doing....

Doz · Post by **Doz** » Sun May 06, 2007 6:46 pm

DavidRutherford wrote:I *think* that's a choke corrector. Its purpose in life is to back the choke off a bit if you put your foot down a bit hard while the choke flap is closed.

Have you had the jets out of your carb? Mid range flat-spotting is often caused by blocked emulsion tubes.. (that's assuming your carb has emulsion tubes... what type and style is it?

Now that makes more sense... it's not a mid range problem, it's when your toddling along bearly touching the throttle. I dread taking the carb apart after busting the gasket on my last one... £30 for a kit and 3-4 weeks delivery prompted the purchase of this one from a scrapper...

It's a solex. I'll venture outside when the rain calms down and have a look...

mountainmanUK · Post by **mountainmanUK** » Sun May 06, 2007 6:57 pm

Hi Doz,
Sorry I don't know the correct name for the component, but I THINK it's similar to a problem I had on my BX14 (Solex carb),
There is a thin rubber bellows / diaphragm - type thing, if you remove the 4 small screws. IIRC it has something to do with fuel enrichment / choke.
The diaphragm on my 14 had a small split in it, and consequently when I blipped the throttle fairly sharply, the extra vacuum created didn't operate that link rod piece correctly, causing the fuel mix to not be enriched properly...causing the same 'flat spot' that you are getting.

I got a replacement off a scrappy, but that was 5 or 6 years ago, when BXs were a lot more common in scrapyards than today!

Hope this helps, although I'm no mechanic!

Dave

kiwi · Post by **kiwi** » Mon May 07, 2007 2:40 am

I got one of them things on my 19TZS, I was told that it could be a unique thing in NZ because of some import restriction type thing. But this loks now not the case so be interested in the replies on this.

Doz · Post by **Doz** » Mon May 07, 2007 8:41 pm

mountainmanUK wrote:Hi Doz,
Sorry I don't know the correct name for the component, but I THINK it's similar to a problem I had on my BX14 (Solex carb),
There is a thin rubber bellows / diaphragm - type thing, if you remove the 4 small screws. IIRC it has something to do with fuel enrichment / choke.
The diaphragm on my 14 had a small split in it, and consequently when I blipped the throttle fairly sharply, the extra vacuum created didn't operate that link rod piece correctly, causing the fuel mix to not be enriched properly...causing the same 'flat spot' that you are getting.

I got a replacement off a scrappy, but that was 5 or 6 years ago, when BXs were a lot more common in scrapyards than today!

Hope this helps, although I'm no mechanic!

Dave

Sucking on the pipe

causes the little rod to move and it holds it's vacuum well, so I don't think it's split... it just seems to work better with is screwed down so it's not operating!... I'm wondering if the choke mechanism should render it inop when the choke's come off, and mine isn't, leaving it working when the car's warm. Been out for a bit of a jaunt this afternoon and I have to say the flat spot is almost non-exsistant ...