Sunday 11 March 2012

Tuning Carbs

Finally got round to trying to sort the carbs out as they have always been a little bit lean. Took the car for a drive to get her up to temperature and then I removed the airfilters.


Started the process by loosening the throttle nuts so both carbs worked independently and then I gave my new Gunson Carbalancer a go. Unfortunatley the Gunson gizmo didnt fit between the cap head screws on the filter back plates so had to remove them as well.


Anyway, rotating the bezel on the Gunson I got a reading from carb 1 and then moved across to carb 2 which was slightly different so I tweaked the idle screw to match the airflow on both carbs. I then moved on to the mixture and using the lift pins on both carbs the revs died very quickly confirming they were both running lean.


Starting on carb 1 I rotated the bottom nut anticlockwise (when viewed from underneath) to adjust the jet and enrich the mixture. Each time I moved 2 flats (6 flats to 360 degrees) I used the lift pin to check what was happening and after 8 flats the revs just increased before settling back again, perfect. I then repeated the process on carb 2 and this time reached the same outcome after 4 flats anticlockwise.

The throttle nuts were then tightened up ensuring both carb pistons rise together when using the throttle (that bit wasn't as easy I thought) and then retested both airflow and the lift pins again and all was the same. The idle RPM had changed slightly and so I adjusted the idle set screws to 700 RPM and then went out for a spin.

Definitely a good result and the car was smoother and seemed to have a little more power. Now comes the downer.... I'm not 100% sure but I think something is rumbling from the rear. I get lots of cabin noise from rear boards anyway and the tools are also stuck down by the spare wheel and the roads are pretty bumpy and the Koni shocks are very firm ride but mmm... I hope I'm wrong and its just road noise or the harsh ride, we'll see.



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