GJ Sigma Carby tuning advice needed

[Shifta]

It's been a while since I tuned a Carby car, and that was my Siggy turbo so it wasn't your typical Carby. My GJ wagz has a different Carby to a GK so my GK manual is no help to me. There are two main adjustment screws - one flat head screw low down near the manifold, and one Phillips head screw near the accelerator linkage. Logic would say that the first flathead screw is the fuel mixture and the second Phillips head is the idle. Can anyone confirm? I attempted to use the old wives tale "wind all the way in, bring out 2.5 times" method and it was hunting for fuel and didn't sound right. Now I've just adjusted both screws till the motor sounded smooth. I'm keen to confirm though if anyone has any tips? Thanks in advance!

[Scorpma82]

Yes, the screw next to the butterfly/throttle linkage is for us idle

What rpm is ur engine at for idle???

Has ur fuel economy changed since the tune???

[Shifta]

Thanks mate. Only did it yesterday so no idea on fuel economy yet. Hard to say on rpm too as it's a GL and has a clock rather than tacho. I was aiming for 750ish by sound but it's a guess! The hard bit is the mixture screw - how far to wind it out! Winding it out 1 turn seemed to be the same as 2-3 going by feel.

[zabatron]

To adjust air/fuel mixture,wind mixture screw in clockwise until the engine slows and begins to falter,then turn the mixture screw anti-clockwise until the engine runs smoothly again,but does not lose speed or hunt.If idle speed has changed,re adjust using the idle speed screw(do not re adjust mixture screw to alter idle speed).Note,this procedure must be carried out with engine at normal operating temperature(fully warmed up),and with ignition timing set correctly.

[Shifta]

Thanks mate. Weird thing is, I wind the mixture screw in and it stops before the car tries to stall - won't go in any further. My Timing light decided to die so I've attempted to tune by ear. Seems to be running ok, gutless as but I'm assuming that is the 2 litre auto at fault

[Sigmaproject]

The mixture screw is basicly for fine tuning to meet emissions. So right in or right out you would need an exhaust gas analyser to tell the difference.
I have driven a 2.6 auto..so I can just imaging how SLOW a 2 litre auto is going to be.

[75wagon]

The mixture screw only effects the mixture on the idle circuit, so when you adjust the mixture screw that's all you are doing.
The actual jetting of the carb determines the mixtures while the car is driving at anything above idle.
To adjust the idle mixture screw make sure the idle speed is set low, the lower you get the idle, the more effect adjustment of the mixture screw will be.

What setup does a GJ Sigma use for the gearbox to know what the accelerator is doing?
The GB Galant auto I use to own had a cable, I just changed the adjustment (tightened the cable so the auto box thought I had my foot down further on the accelerator pedal), that livened it right up. With the 1600 and twin carb set up I had, I could get it to spin the wheels for a couple of hundred metres in the wet by only putting my foot on the accelerator. Made it a lot more fun to drive.

Dave...

[Shifta]

Thanks Dave, will drop the idle next time I'm tuning it and try the adjustment again. Not sure on the Auto setup but sounds logical!