How to adjust Throttle adjusting screw
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Sandun
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How to adjust Throttle adjusting screw
Hi.....How to adjust throttle adjusting screw - is it use for adjust idle speed ( I use it for adjust idle speed) but in the idle speed ignition light is on my car - and when I paddle clutch, engine slow and stop- so it says idle speed not enough ? - how to adjust idle speed better - How I know idle speed enough ? what is the problem ?
Re: How to adjust Throttle adjusting screw
Assuming that you have the standard carb on a 948 or 1098 engine, there are three adjustments. Below the crab is the jet adjusting nut. This changes the mixture, and if the car is generally running OK, then you should not need to touch it. On the side of the carb you will see the throttle stop screw (slot head facing upwards, screws through the body of carb. When the engine is at normal operating temperature, use this screw to set the idle speed. It is normal for the ignition light to flicker at idle speed (with a dynamo) and then extinguish when the speed increases. It is also normal for the revs to drop slightly when operating the clutch. You need to set the throttle stop screw so that the engine is running faster enough that it does not stall, but also slow enough that it is not racing. It may be necessary to adjust the mixture slightly to get an even idle speed without hunting.
The third adjustment is a screw facing downwards that bears on a cam operated by the choke mechanism. As you move the choke cable, you will see the cam move. It pushes on the screw that opens the throttle slightly. This is a "fast idle" for when the engine is cold - it has to idle faster until warm. With the choke in the normal run position, the screw should be adjusted so that there is a small gap (a few thousandths of an inch, or two cigarette papers thickness) between the end of the screw and the cam. This should be done before attempting to set the normal idle speed because if the fast idle screw is touching the cam, it will stop the throttle from closing fully and therefore interfere with the normal throttle stop screw mechanism.
If you have a tachometer, then a good starting point is an idle speed of around 1,000 rpm and then adjust until it sounds right and the engine is happy.
Hope that all makes sense.
The third adjustment is a screw facing downwards that bears on a cam operated by the choke mechanism. As you move the choke cable, you will see the cam move. It pushes on the screw that opens the throttle slightly. This is a "fast idle" for when the engine is cold - it has to idle faster until warm. With the choke in the normal run position, the screw should be adjusted so that there is a small gap (a few thousandths of an inch, or two cigarette papers thickness) between the end of the screw and the cam. This should be done before attempting to set the normal idle speed because if the fast idle screw is touching the cam, it will stop the throttle from closing fully and therefore interfere with the normal throttle stop screw mechanism.
If you have a tachometer, then a good starting point is an idle speed of around 1,000 rpm and then adjust until it sounds right and the engine is happy.
Hope that all makes sense.