Auto Choke Cold Running Adjustment

[D366Y]

Slightly odd one, the GL has started pissing me off recently because it starts OK, but I'm then having to keep my foot on the throttle to keep the engine from dying. I've now got to the point of left foot braking everywhere because if I take my foot off the gas and the revs drop too low the car stalls.

However, when I got to work this morning after sitting in traffic for a bit the engine temperature had got up to about halfway (finally) and it was running fine.

Is there anyway to adjust the auto choke apart from the idle screw to help? I'm pretty sure my carb is one of the 'tamperproof' carbs as I can't for the life of me find a mixture screw at all and the hole where it is on the manual choke I have on the Laser is blanked off

Cheers
Danny

[Paul G]

If you take the air filter off you will find a fast idle adjustmet screw on the rocker cover side of the carb. It is down in the mechanism behind the choke unit. Turn it in to raise the fast idle when the car is on choke - I'd suggest no more than 1/4 turn at a time until you can get the car to keep running.

[D366Y]

Perfect thank you Paul!
I've just invested in new points, dizzy cap, rotor arm, spark plugs, condenser, coil and a carb rebuild kit and have been going through trying to eliminate an ignition problem but never knew this was there!

Thanks

[D366Y]

Went out for a fiddle at lunch and it seems to have worked so far but the true test will be later but certainly better already!

Thanks Paul

[STEVEW]

Hi D366Y
I hope your problem is solved but making adjustments whilst cold and running could cause problems.
You might drop the screwdriver.

[Bug]

You should notice that the adjustment screw acts on a cam. As the choke mechanism warms up, it twists the cam and the idle speed drops.
The cam has an extra step, right near the fastest idle end. It used to be quite common for the spring in the choke mechanism to wear so that the cam did not get pulled right the way back. So you wouldn't get the fastest idle speed setting. Be aware though that the choke will only open to that fastest part of the cam in very cold weather.
When you pump the throttle twice you are not only priming the carb with fuel, but you are lifting the fast idle screw off the cam, allowing it to spring back to the fully open position. If the choke mechanism is weak or stiff and you pump the throttle very quickly, you do not give the mechanism time to move back to fully open, and the fast idle screw traps the cam halfway.
On top of the choke housing is a centre alignment mark, sometimes with smaller ones either side. Loosening the three retaining screws and turning the housing a little can tension the spring and make it work a bit better, although this is a quick fix, masking the real issue.
Related to the stiffness of the choke action is another little fault that sneaks in un-noticed. The spindle of the auto-choke where it passes through to operate the cam and the choke flaps runs thorough the choke assembly inside a hole that is lined with a plastic sleeve. Over the years this sleeve wears and snags, catching the spindle and causing it to stick. On a few occasions I have simply pulled the remains of he sleeve out, squeezed a bit of grease in the gap and left it like that. Works perfectly well.
Back in the 80s when it was popular to slag off the auto-choke, I used to take great delight in fixing them. When set up correctly they are a very good bit of kit, but people see them as some kind of black art, or just follow the herd and throw it away.

[STEVEW]

Bug wrote,

You should notice that the adjustment screw acts on a cam...

Great piece of information, a classic example of what these forums are all about.

Thanks Bug.

[Bug]

When you pump the throttle twice you are not only priming the carb with fuel, but you are lifting the fast idle screw off the cam, allowing it to spring back to the fully CLOSED position. If the choke mechanism is weak or stiff and you pump the throttle very quickly, you do not give the mechanism time to move back to fully CLOSED, and the fast idle screw traps the cam halfway.

Please note my correction above..

I used to pump the throttle 'down, 1,2,up,1,2,down,1,2, up' to be sure it had time to sort itself out.
As the accelerator pump only has a small amount of fuel in it, holding the throttle down longer will have no effect on fuel squirted in, no chance of flooding etc.

[D366Y]

Bug wrote,

You should notice that the adjustment screw acts on a cam...

Great piece of information, a classic example of what these forums are all about.

Thanks Bug.

I concur, fantastic bit of info!

I cut my teeth on the manual choke carbs I've had on the 1.6 and the auto choke has been a bit of a dark art to me but to date I've not had an issue with it so have left well enough alone.

It sounds like the carb could do with some TLC though so once the engine rebuild is done on the 1.6 and she's back on the road I'll take the time to strip the carb down, clean it up an bit and give it a general service as it sounds like that's what's needed

Evidently after my fiddle at lunch yesterday the engine was still a bit warm as when I went to start it at at the end of the day it was revving like nuts Lowered it back down again when I got home and again this morning just fine tuning it but so far its going well so thanks to Paul for the pointer!

Thanks
Danny