Questions on Dellorto vs Solex

[Huib Geurink]

There should be no clearance between the lever of the pump and the nuts on the adjust rod. It would in fact be impossible to have clearance if everything is assembled all right.

On the rod there should be a spring first, then the lever of the pump, then the adjust nuts.

The spring pushes the lever against the nut when the throttle is closed and at low openings of the throttle. When opening the throttle fully it reaches a point about half way where the lever of the pump reaches it maximum position. The spring starts being compressed. The means the acceleration pump is supposed to work at lower openings of the throttle only. At higher openings it does not work. This is logical and to be expected.

Note that the lever is operated by the spring and not by the nut.

The distance between the tip of the rod and the lever varies between 15 and 18mm between several carbs I checked. Note that you should not use these values to adjust the nuts, but only to verify whether the current setting is in range or out of range.

If I understand the mechanism correctly adjusting the nuts would not change the opening angle of the throttle where the pump starts to work but the opening angle of the throttle where it stops working. Neither does adjusting the nuts change the amount of fuel injected per small movement of the throttle. Since the nut determines at which throttle position the pump stops to operate, it will influence the total amount of fuel injected when the throttle is moved from fully closed to fully open.
I deduced all this from looking at the carbs. I may be wrong. But if I am right you might try adjusting the nuts by measuring the pump output over a certain number of full strokes.

Look at the very bottom of http://www.viva-lancia.com/fulvia/qanda ... llorto.php
It says the pump should produce 2,5cc of fuel per 20 strokes.
In the Technical Databook which is on the CD's I am selling on this site, there is similar data for each of the Solex types.

You would have to mount the carb on a stand. Connect a small fuel tank a little bit higher. Operate the throttle and collect the fuel coming from the carb.

I bet the springs are missing or there is another assembly error.

[Jim]

Thanks Huib - I will have to wait a couple of weeks before I can check. From memory the pumps aren't set up to operate the way you describe, so I suspect that you're right - something is wrong either with the way they're assembled or the setting itself....