Setting floats with the gauge

[Christien]

I've got the PMO float gauge and today checked my float levels for the first time. All 4 are remarkable similar, all just exactly at the lower line of the 2 lines for Webers. The directions from PMO say one shim = 3mm. Well, the distance between the 2 lines is only 2-3mm, so if I add a shim I'll be at the top line, or perhaps slightly above it. I opted not to add any - should I? Is it better to be on the high or low side?

[1QuickS]

Shims do not correlate to fuel height adjustment; typically a 0.010" shim will change fuel height approximately the distance between the lines. I tend to set fuel level so meniscus is aligned nearer the top line, a little help in enriching transition onto the mains.

Be sure to check fuel pressure; specification is 3.56 psi but plus/minus .5 psi is probably OK if you don't have a fuel pressure regulator to control it.

Also: Very important to check fuel levels with engine running, anything else is a static setting and does not replicate actual dynamics of fuel delivery.

[Christien]

So better to err on the high side rather than low?

I need to get a pressure gauge to check fuel pressure. I had a shop replace it years ago and they said it was internally regulated, or set to the right psi, or something, so I never thought twice about it.

How can you check it with the engine running? Wouldn't the engine vibration make it impossible to get a reading, because the fuel in the gauge would be bouncing around?

[1QuickS]

I check every carb on a running engine; over 600 floats set on a running engine without problems; get a small flash light to help illuminate the fuel in the vial. If engine is using solid mounts or is missing badly then the fuel will move a bit more but the overall fuel level isn't changing so the meniscus is stable.

I set floats with nominal shims on the bench (after blueprinting the float geometry and other adjustments, etc.) and observe the fuel entering the gauge with the engine off. If the fuel level stabilizes I then start the engine. If the float sticks during the initial fuel bowl filling (sticking occurs for various reasons) you can take a small diameter wire, hex wrench, bamboo skewer, etc. and "tickle" the top of the float by passing the wire down through the vent pipe that extends up between the air horns.

Be sure to observe fuel filling initially with engine off and set fuel level with engine running.

The two lines are the range of acceptable levels and being within them probably is indiscernible to engine performance; I err to the top of the tolerance band.

[911pcars]

Careful. Erring slightly too high may cause an over-rich condition that may cause one or more spark plugs to foul.

Sherwood

[flash951]

I have just got my Webers restored. I have not managed to tune them in yet. I've fitted new "needle valves" and since the "shims" din't came with the repair kit, I've just used thin cobber ones I found laying around in my tool boxes. I wasn't aware of the importance of fuel level and so one, I'm completely new at this. I have purchased a syncmeter and a fuel level gauge here from Pelican, after searching the forum a bit.

Today I used the fuel level gauge and checked the right Weber bank. Both floats on that side was just slightly above the upper of the two markings for the Webers. I tested first without the engine running and then when the engine running, the readings was the same either way.

My question: With the fuel level just above the upper mark and not between the two marks, is it OK or should I bother the shims it to stay between the two marks?