Further ICT questions

[matt-me]

http://forum.earlybay.com/viewtopic.php?f=4&t=22589&p=197730&hilit=ICT#p197730" onclick="window.open(this.href);return false;

Following on from the above thread, I had ICT's fitted a while ago and am pretty happy with them.

BUT, I am finding that after running for about 20mins/half an hour, when i sit at idle at say traffic lights and then go to pull away I produce a cloud of white smoke. This will happen only once in a while, and only generally happens when you pull away from a stop, at say traffic liights, after you have been driving. It doesn't always happen and you can go on a run for about an hour, mixed driving conditions, without it happening at all. When a friend had been following me he has noticed a slight petrol smell, so initial thoughts are it could be running rich.

I have read on a link (Redline) to an ICT set up guide about 'Lean best idling' procedures. It reads 'at times it may appear to be showing signs of richness or flooding but it is really a lean condition'. Which suggests the jets need looking at, hence the link to above.

Does anyone know anything about this? Or could it be something to do with the fuel pump.

My simple thoughts are that when travelling from speed to stop, but idling, there is an excess of fuel which doesn't burn and builds up, then once it clears, it is fine for a while before it happens again. Does that make any sense?

Any thoughts kind people? I would like to get it right in my head before i take it to a specialist, which i will be doing sometime very soon.

Thanks Al

 

[sparkywig]

Could be the fuel pump pressure forcing fuel past the float needles. It can generate up to 8 psi, which is way too much for the 34's to handle.
Have you got a regulator fitted?

 

[matt-me]

Hi SW, No I haven't got a pressure regulator fitted. I did change the pump to a brosal one (and new rod) when i converted to alternator. Do you know if this pump pushes out the same pressure as the og one. I didn't realise there were various options on pumps. I did buy a pressure regulator but i don't think you can alter the settings, i didn't have it fitted as i was told it wasn't needed, maybe i should.

Does it sound like my simple analysis could be what's happening? The bus seems to be driving well enough. I am going to book her in to a tuning specialist, someone like southern carburettors, near to me, as they can check what's going on and hold stock of various weber jets etc, but we're taking the bus away for the week down to dorset next week. As i say it has been happening for while but i want to understand whats going on and get it sorted.

Cheers

Al

 

[Trikky2]

Black smoke = Rich mixture.

Blue smoke = Burning oil

White smoke = Moisture

 

[matt-me]

Thanks Trikky but what can i do about moisture, how does it arise? I trust something needs to be looked at.

Al

 

[Trikky2]

Thanks Trikky but what can i do about moisture, how does it arise? I trust something needs to be looked at.

Al

What most people see as white smoke is in fact only steam and occurs on all cars as they warm up. The more moisture there is in the atmosphere, the more it will produce visible steam in the exhaust gases.

Most vehicles will stop producing this steam as they warm up to normal running temperature. The time this takes is dependent on many things such as exhaust design, length, engine capacity, ambient temperature etc.

If the vehicle continues to produce steam when fully warmed up its often a sign of a blown head gasket letting coolant into the cylinders.

However, since bays are air cooled it cant be that :lol:

If its doing it when its fully warmed up then its certainly a strange fault and would lead me to look for obscure things, like leaks of oil or other liquids onto hot exhaust pipes and heat exchangers, contaminated fuel etc.

You really need to find out if this "smoke" is actually coming out of the exhaust pipe itself or whether its coming from around the engine and exhaust area to pin it down more precisely.

Let me know what you find

 

[sparkywig]

Unburnt fuel produces a white cloud as well.

 

[Trikky2]

Unburnt fuel produces a white cloud as well.

Only if in seriously large quantities and wholly un ignited, else it will be black and sooty. The kind of quantities due to heat evaporation would represent very poor mpg and a very serious fire threat IMO. Even with one cylinder not firing its mixture I cant see it forming a cloud of white smoke tbh.

 

[matt-me]

Thanks chaps, much appreciated. The smoke is definately coming out of the exhaust. I will monitor it but if unburnt fuel is white too, then i think it is more likely something to do with this. I suppose i am hoping, it is possibly incorrect jetting of the carbs, which, after reading the above thread, is the cause, which i aim to have someone look at and get sorted out.

If unburnt fuel, can it do any damage until i get it looked at, apart from to my pocket?

If there is any further input from anyone, it too would be much appreciated.

Cheers

Al

 

[sparkywig]

Have a look at this thread Matt.

http://forum.earlybay.com/viewtopic.php?f=4&t=22589&p=196979&hilit=weber+34+jetting#p196979" onclick="window.open(this.href);return false;

 

[matt-me]

Thanks SW, that's the thread which prompted the questions and I was hoping you'd pick up on it to offer me your advice.

Did you do the works yourself and was it pretty straightforward? I don't know much about carb's apart from the old SU's i used to have in my coopers/mini's and they were totally different, pretty simple now i compare.

What i don't have are any diagrams of the ICT's, and how they are put together, as these seem to have got lost. I have the Lean idle procedure, but when you talk about emulsion tubes etc i am lost. If you have any pointers, as i wouldn't mind having a go, using your set up, as i can then provide feedback too. How do you know what jets etc you have, are they marked? when you have taken the carb apart?

Thanks again

Al

 

[sparkywig]

No worries, I'll strip an old carb down and post some pics later.

 

[matt-me]

Cheers Mate, no rush as I am going away for the weekend so if you post and get no reply, it's cos the campsite don't do internet. Thanks in advance.

Al

 

[sparkywig]

Here you go, sorry about the quality of the iPhone camera. :roll:

Brass screw in the centre by the main venturi is the air corrector, and under here is the emulsion tube.
The main jet is the angled brass screw at the bottom of the float chamber, don't worry about the one next to it.
The idle jet is behind the brass plug on the left of the carb body next to the square accelerator pump housing.

From left to right

idle jet, main jet, air corrector jet and emulsion tube.
You can see the extra holes in the F78 emulsion tube, the F3/F6 emulsion tubes don't have these, so allowing the idle jet to do its job without adding early fuel from the main jet.

Just for your information, I've fitted 55 idles, 150 mains, 170 air correctors and F6 emulsion tubes, but kept the 175 needle valves and fitted a fuel pressure regulator to keep the fuel pressure to about 2 - 2.5 psi.
Mine is running fine.