Idle Mixture & idle setting up?

[andyzeetec]

Hi all

Got a lumpy erratic tickover so had a play around with the mixture. Is there a recommended number  of turns out for this screw, 1½  or 2? as a std setting?
Is the idle mixture set for best running or to pass mot at not necessarily best engine running?

As I understand the way to adjust the idle mixture is to screw in slowly till nearly stalls, then back out slowly to find the highest tickover/revs, sweet point, keep unscrewing till runs lumpy again then screw in ¼ turn.
So I screw in until nearly stalling, screwed  out to find highest revs which came back to my lumpy tickover but the revs did not really increase to a peak, didn’t want to unscrew it too far or any further  in case screw came out.

Am I doing it correctly,which way is leaning it up, do I need to remove carb & clean jets, check float height, does adjusting the idle screw affect starting in combination with mixture screw as it seems harder to start now?(I did notice on carb that when you set full choke the throttle butterflie/s open a fraction and also if you open the throttle with full choke, the choke lever now drops, comes off slightly)

Like an idiot I forgot to screw mixture screw in and note the turn # before playing around with it.

Many Thanks

[Da Londo]

Got a lumpy erratic tickover so had a play around with the mixture. Is there a recommended number  of turns out for this screw, 1½  or 2? as a std setting?
Is the idle mixture set for best running or to pass mot at not necessarily best engine running?

1½  is about right and I always used to fiddle after MOT. You runnning a BIS?

[andyzeetec]

Got a lumpy erratic tickover so had a play around with the mixture. Is there a recommended number  of turns out for this screw, 1½  or 2? as a std setting?
Is the idle mixture set for best running or to pass mot at not necessarily best engine running?

1½  is about right and I always used to fiddle after MOT. You runnning a BIS?

Yes

[Pete126]

Hi all

Got a lumpy erratic tickover so had a play around with the mixture. Is there a recommended number  of turns out for this screw, 1½  or 2? as a std setting?

The 1 1/2 to 2 is a starting point not a standard setting
 
Is the idle mixture set for best running or to pass mot at not necessarily best engine running?

There's no difference, if its set up properly the engine will run smooth and produce less Co2

As I understand the way to adjust the idle mixture is to screw in slowly till nearly stalls, then back out slowly to find the highest tickover/revs, sweet point,

That's how i was taught to setup the idle mixture in 1852 Forget about the 1/4 - 1/2 turns it doesn't work that way
(keep unscrewing till runs lumpy again then screw in ¼ turn.
So I screw in until nearly stalling, screwed  out to find highest revs which came back to my lumpy tickover but the revs did not really increase to a peak, didn’t want to unscrew it too far or any further  in case screw came out)

Am I doing it correctly, YES

Which way is leaning it up,

The idle mixture screw is shaped like a cone, this fits into a pre-drilled hole, by screwing it in this leans the idle mixture (only) by filling the hole thus limiting the amount of petrol into the venturi   


Do I need to remove carb & clean jets, check float height,

Not if the above sorts out the problem


Does adjusting the idle screw affect starting in combination with mixture screw as it seems harder to start now?

NO - its more likely to be points, plugs or ignition timing

(I did notice on carb that when you set full choke the throttle butterflie/s open a fraction and also if you open the throttle with full choke, the choke lever now drops, comes off slightly)

That's Normal

Like an idiot I forgot to screw mixture screw in and note the turn # before playing around with it.

Many Thanks

[andyzeetec]

Thanks Pete. 

[andyzeetec]

Got the carb off, jets were partially bunged up in the float bowl, so maybe that was the cause of the struggle starting/rough idle.

My question is the regarding the pic below of the idle screw (thin screw). The rubber seal had a few bits of shavings come off as I unscrewed it, so I want to renew it, but there are only o-rings in the carb kit. The seal on the screw looks like it is a different type. Can anyone help, as I dont want to cut it off and fit an O-ring if it's not suitable.

Thanks.

 

[poxxxy]

What did you do with the idle screw seal in the end?

[andyzeetec]

It was an o ring but well and truely shot, Cut it off and put a new one on with a drop of oil to seal.

:)What did you do with the idle screw seal in the end?