Hi
My x19 has just passed its MOT first for 2 years ( i have had the car for 8 months )
But all is not well. It wont bloody idle, i have changed.....
the carb
the points
the plugs
the leads
cap and rotor arm
the coil
the capasitor
the carb base gaskets
the compresions are all 120 and it runs very well above 1300/1400rpm, with no smoke, below this speed it misses and spluters to a stop.
Please help as i am at my wits end....:bang:

When you say 'the carb' ....you mean the whole thing? It has to really be with the Carb setup - have you checked the float/jets etc?

Done the float level, and cleaned the carb.
There is no mixture screw?

Hi messy1964

Try this thread here it my help

https://www.fiatforum.com/x1-9/310784-running-issues.html

Thanks. ill have a go at all that when i get a chance.
I have done the timing before, but not at idle, as it wont idle!?!

One thing that is odd. People talk about a mixture screw, but neather of the carbs i have have one?

What i really need is to fit a known good carb, then i could get mine rebuilt by an expert. Or think again.

I assure you, the carb does have an idle mixture screw. It would be impossible for the car ever to have idled without it. If it has never been adjusted (very, very unlikely) it might be covered by a brass or plastic anti-tamper plug.

On some 1500's there are even plastic plugs in the boot firewall that line up with the adjustments so a long screwdriver can be used for ease instead of a fiddle stubby driver inside the engine bay. The isolation plate between the carb and the manifold has a catch tray for the screw in the unlikely event that it drops out (it works too!)

Of course if it just won't idle there is a possibility that the screw is already gone and the idle mixture port is just sucking air instead of fuel....

Cap still in place!!!!
That changes everything, as soon as i get the chance ill give it a go.

What is a good starting position for it?

Cheers Ed

What a idiot i am!!!!
I was looking for the mixture screw in the wrong place! I expected to to find it right at the back of the carb. But the little bugger was hiding round the corner all along I do feel a total spanner.

Cant wait to try it now, but have to look after the kids until the weekend. Fingers crossed.

There is no "good position" to start from. You need to know if the carb is under or over fuelling at idle once the choke is off. Without an exhaust sniffer you are going to need to check the spark plugs to get a clue. If you have to start from nothing then carefully turn the screw until it bottoms out and then wind it back a little - this will give a very lean idle mixture.

Tightening the screw leans out the mixture, loosening the screw enriches it. Just make small adjustments. If the screw doesn't really offer much resistance while it is turning the odds are that the rubber o-ring on the screw has rotted out allowing the screw to turn freely (even from just engine vibration) - this will need replacing.

Before you do that you need to make sure that the primary throttle plate is not closing too much. If the engine will idle with just a tiny amount of throttle applied then the plate is probably closing too much and it is a different screw (still near the base of the carb) that moves the throttle stop. It is labelled as the slow idle speed adjustment on diagrams.

If you look closely down the primary barrel you'll see a series of pinholes in the side of the barrel - these are called the progression holes, they allow a tiny amount of fuel to trickle through while the throttle is nearly closed. The venturi won't work at the sort of air speeds you get while the throttle is closed. The last part of your potential problems come from these getting blocked up - if adjusting the idle speed and mixture seems to make no difference the odds are one or more of the progression holes is blocked in which case the carb needs a really good clean. Another way to double check this is to open the top of the carb and have a look in the bottom of the float bowl - if you can see what looks like fine glitter then you really need to get it cleaned. The flakes are actually remnants of fuel tank that have corroded, fine enough to get through the filters but big enough to cause trouble. Worse still are small lumps of black - these are from the fuel pipes themselves, if there are any of these then you need to replace the pipes as they've started to fall apart internally (even if they look perfect on the outside). Either way if you can see foreign bodies (no matter how small) in the float bowl it will need cleaning out!

Lovely smooth 1000rpm idle

Once i found the screw, i found it was all the way in. On my other carb it was all the way out! No wonder they both did not work.

So i set the screw about 1.5 to 2 turns out and hay presto it started first turn and ran so smoothly. After it had warmed up i simply lowered the idle to 1000rpm on the main idle set screw....wonderful.

I think the reason that i could not find the screw is that my last car that had a carb like that was a 1.5 Alfasud and the position that the screw is in on that car had a brass blanking plug, so i ( incorectly ) assumed that the mixture screw was behind that and set. So the trouble must have been something else.

But thanks to you all, i was put right and now cant wait to get out and about.

Cheers Ed.