Will high float level make mixture more or less rich?

[sandiego]

I have solid motor mounts and sometimes one float level runs very high. Until I can put in semi-solid mounts I need to know if this high float level will make the mixture richer than when I checked the A/F mixture or leaner, so that I don't burn a valve or something.

[Trackrash]

It could possibly be richer at transition since the main jets may start operating sooner.
The danger is raw gas sloshing into the intake.

[chris_seven]

Originally Posted by sandiego

I have solid motor mounts and sometimes one float level runs very high. Until I can put in semi-solid mounts I need to know if this high float level will make the mixture richer than when I checked the A/F mixture or leaner, so that I don't burn a valve or something.

Are you suggesting that vibration is causing one float to stick?

If the two carbs behave differently there may well be a minor fault in one unit and the float pivot may be worn.

Are both floats affected in the one carb?

[stownsen914]

Hi floats can affect transition timing, and if high enough could allow unmetered dumping of fuel directly into the intake ports (which will make the engine run like crap). I've heard that solid motor mounts cause all kinds of issues in fuel metering for the PMOs. I know Richard from PMOS warns this. Aside from that, I'm not aware that high float levels cause richer running, per se.

Scott

[racing97]

Only in a static condition the float level will affect the mixture, the rich or lean is dependent on the holes and there positioning towards the top of the emulsion tube the higher the holes and the diameter will affect a lean condition in the metering in operation at higher RPM.

regards

[1QuickS]

Emulsion tubes are designed for a specific float level.

If the float level is high then the transition onto the mains is advanced and if float level is low then it is retarded. Additionally, all partial throttle operation on the main circuit is affected by fuel emulsification by the e-tubes so fuel levels not at design height will affect partial throttle mixtures to those cylinders supplied by fuel from those mis-adjusted bowls.

If float level is high then the fuel in the emulsion tube well is also high so it will require less vacuum to pull it to the transfer port leading to the hollow wing in the auxiliary venturi which is main circuit operation.

Sticky floats caused by:

• bent shaft on the brass screw that the float pivots on
• float rubbing on the wall of the fuel well
• the tab on the float where the needle valve contacts is not perpendicular to the axis of the needle when float is at design height (an angled tab will generate a side-load at the tip of the needle which will upset the ability of the needle to close)
• the tab on the float where the needle contacts has a "divot" from contact with the needle, like the non-perpendicular issue mentioned, the divot will cause a side-load issue with the needle
• the needle needs replacement due to wear, these needles have brass needle and seat so they do wear out and need replacement
• fuel pressure too high, design fuel pressure is 3.56 psi and a 1/2 pound variation is OK, high fuel pressure will overcome the needle and overfill the bowls

[JFairman]

It will richen the mixture and increase fuel percolation after a hot motor is shut off as engine heat transfers into the carbs and float bowls. That leads to fuel percolation spill over and flooded out intakes around a half hour after a hot shut down and can lead to backfires while cranking the starter motor and fire in the carburator throats. Been there with Solex carbs on a 912. Almost burned down a set of Solex's once but got the motor started on 2 or 3 cylinders and sucked the fire out in the other throat(s)

I've had Solex 40PHH sidedrafts on a BMW 2002ti, Solex 40 P11 4 downdrafts on a 912, dual sidedraft Weber 45 DCOE's on the BMW and Weber 32 36 downdrafts on a 912. The Solex's are a lot worse with hot engine shut off percolation.

Weber's were not so bad even on hot Florida summer days. They are much better carbs in every way.

[knorrena]

If the float is set too high then raw fuel can dump into the throat of the carb through the vent.