carb running prob 3 branch
Turbo Mini Forums

Got running problem on my mini :( its 1993 carb mini and the carb doesnt have any adjustement just an idle screw. The problem is no power, and its backfiring all the time, when you put choke on it works alot better. Its like its not getting enough fuel, do the three branch manifolds need a different carb? I've had the carb off and inlet 3 or 4 times checking for air leaks but cant find probs with that. Running out of ideas any thought cheers?

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has this just happened of have you changed anything?

What carb is it? And you say it doesn't have a mixture/adjustment screw so i assume it's not a standard SU one?

http://www.turbominis.co.uk/forums/index.p...tid=469104&fr=0

if it is a standard carb it should be a hif model with the mixture screw below the fuel inlet pipe on the side.

one day boost will be mine!

or a hs carb with a big nob underneath so that you can burn your hand on the exhaust

Doesnt sound good for me, running well before i did anything and i put this three branch manifold on with exhaust straight through, had the metro turbo inlet to start with and swaped it for this normal metro inlet and it still running ruff, i did advance the timing and it run better, but wasnt right. I'll have a look for the screw tomorrow but i'm sure it was not like the ones had before

Edited by Zeemax Power on 11th Feb, 2012.

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does this set up normally need more fueling, its back firing bad and running with no power like cant do more than 40mph

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Possibly, I once fitted what was essentially a stage 1 kit and left the standard needle in, I couldn't get it to do anything i wanted it to do myself and couldnt even drive the thing, changed the needle and had a faf myself and it was a completely different story. Might be worth asking somebody familiar with tuning the a series what needle they recommend.
The screw on HIF carbs is in the northwest position looking at the front of the car, you'll need a stubby screwdriver to adjust it.

The haynes manual will tell you how to get the idle speed and mixture set up properly, which should help, but for anything other than idle you'll need a different profile needle to supply the correct amount of fuel to the cylinders.

If you dont know what needle to go for, i got some advice from the people at minispares, i told them the modifications i had done to the car and they suggested a needle that would give roughly the right performance.

For the sake of £6 and a phone call its probably worth a try?

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id check to normal causes too like clean plugs and check timing with a light just to make sure there spot on if you have the vizard book it tells you what spring and carb needles to use with what mods. what carb are you using and what size engine are there any other mods il have a look what need and spring you require for you

Edited by wng691s clubby on 12th Feb, 2012.

Done now needs redoing lol

I would find out what needle comes with the stage 1 kit and try one.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

Cheers for the advice, lads i'm going to try swaping a diff carb on today see if that does any good, do the carb gaskets make any odds cause some have bigger middles observly for diff carbs but that wouldn't cause air leaks would it?

I'm defo going to try a diff needle if you think that might change it

The thing thats most gutting it was running spot on with the standard exhaust, that'll be going back on if i cant work it out.

the cars a standard 1275 and 3branch manifold and stainless back box and straight through and filter. Not done much thats why so depressing

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93 is gonna be 1275 with a hif38 unless something's been changed. Is there oil in the dashpot?

If something is worth doing, it's worth doing half of.

yes and yes john, didnt get round to the mini today hope to have time tomorrow and then we shall see fingers crossed

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Is it a proper 3 into 1 manifold or an lcb? As you may lose too much back pressure if it's a proper race 3 branch.

one day boost will be mine!

Could the mixture screw still have a anti tamper plug in it.. Alan

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i think it has alan, switched carbs tonight and still no joy going to have one last play with with the mixture tomorrow then i'm giving up and putting it back the way it was :(

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chucking a big bore exhaust and manifold on will screw the mixture up,

Bit justice lads, put another carb on and screwed the mixture right in and gave it three turns out and we are back in business,

Apart from going on the rollers is there anyway of knowing if the mixtures right or does it not really matter as long as its running

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A wideband aem gauge, not cheap but the best thing I ever bought.

Edited by bennyy on 14th Feb, 2012.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

What sort damage of over fueling?

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