Carb rack fuel level checks

Just was wondering when wet setting the float levels how far out do I loosen each drain screw? And also if I have the carb rack level on a table and supplied with an aux fuel supply for the test how long should I turn the fuel supply open on prime to fill all the carbs up without overflowing them or messing up the levels too high or too low? Thanks

 

You loosen the drain screw enough so that fuel flows out of the carb bowl and into the clear tube that you're using to check the bowl level. Half turn past when you first start to see liquid in the tube ought to be enough.

And as for how long the fuel supply is turned on... If your float valves are sealing properly, then you should be able to leave the fuel on prime forever. That's the whole concept of the bowl, valve, float, and the level that you're checking. If everything is working properly, the carb will only accept the amount of fuel required to lift the float and close off the valve. It cannot accept more than that.

Now if your float valves don't seal correctly.... Then the carb will continue to accept fuel even when it's not supposed to. If that happens, either you've got severely misadjusted floats or you need new valves.

 

Okay thanks a lot

 

Precisely.

Wet-setting is when you'll discover any issues that might be preventing the floats from doing their job. You WANT to fill the carbs as full as possible, if the float valves work correctly they will shut off at the proper level. That's what you're there to verify/adjust.

A tip: "Cycle" them a few times-- let them fill up, shut off the fuel and open the drains then close the drains and re-supply them with fuel. Do this a couple times before you take a reading; quite often the very first reading isn't representative of what they will be doing.