Weber Tuning Questions
Posted: Mon Apr 17, 2006 11:18 am
I was tuning my carbs today (twin Weber 40DCOE18). Its amazing how you can get the engine running quite smoothly on just 3 pots.
That wasn't the intent of course, but after noting that I could produce no response when adjusting the idle mixture screw on pot 4, I pulled the HT lead and even that produced no difference at all in idle speed. So pot 4 isn't firing (at least at idle). The plug is wet and the spark is clearly present. All the jets are clean and the idle and progression holes are clear. It does seem like fuel is getting to the pot, but maybe not enough. Any suggestions?
Different issue: when using a synchrometer to adjust the throttle spindle setting between the twinned carbs, I found that I can produce an identical volume of air (3.2 kg/h) through pots 2-4, but pot 1 takes significantly more (4.8kg/h). Now since pots 1 and 2 are on the same spindle, I can only assume that the butterfly on pot 1 is somehow set differently to those for pots 2-4. Would you agree with my train of thought?
Matt
That wasn't the intent of course, but after noting that I could produce no response when adjusting the idle mixture screw on pot 4, I pulled the HT lead and even that produced no difference at all in idle speed. So pot 4 isn't firing (at least at idle). The plug is wet and the spark is clearly present. All the jets are clean and the idle and progression holes are clear. It does seem like fuel is getting to the pot, but maybe not enough. Any suggestions?
Different issue: when using a synchrometer to adjust the throttle spindle setting between the twinned carbs, I found that I can produce an identical volume of air (3.2 kg/h) through pots 2-4, but pot 1 takes significantly more (4.8kg/h). Now since pots 1 and 2 are on the same spindle, I can only assume that the butterfly on pot 1 is somehow set differently to those for pots 2-4. Would you agree with my train of thought?
Matt