Weber 40IDA3C Float Gauge Verification

kucharskimb · 01-31-2007, 09:02 PM

I have PMO's float level gauge. It measures approximately 35mm from the center of the brass screw-in fitting to the upper line.

Bieker Engineering maintains that the correct level should be on the order of 41mm. Bieker maintains that the 35mm line is for Zeniths.

I called Dieter's in San Diego and asked Steve Grosekemper to measure his actual Weber manufactured gauge, and he agrees with PMO's measurements (35mm).

Anyone care to confirm or deny the correct gauge height as measured from the center of the brass fitting to the upper line?...

If you have a PMO gauge that differs from mine, please indicate so.

Thank you

kucharskimb · 02-02-2007, 06:11 PM

bump. need a little help...

CurtEgerer · CurtEgerer's Garage

It's 35mm. I just had my 40IDA's rebuilt by Bieker. I set the floats using the standard gauge (from Stoddard) and the upper set of lines are at 35mm - that's where I set them. The car runs perfectly.

kucharskimb · 02-03-2007, 06:23 AM

thanks. that gauge looks like mine. unfortunately, it is an aftermarket one. i would agree, that while using the 35mm line the car runs fine.

does anyone have one that actually says Weber part no. XXX. hoping to verify that the almighty Weber engineers intended 35mm.

Tooth911 · 02-03-2007, 08:01 AM

Pics would be great! for those of us heading down this path very soon.

CurtEgerer · CurtEgerer's Garage

I'm not sure what more verification one could offer than the fact that the car runs perfectly when they are set via the 35mm marks .....

The float level is sensitive - not to mm's - but to fractions of mm's! If the float levels were set at 41 mm above the bowl drain centerlines, the car would not run. It would run poorly if it were off by only 1mm.

The standard float gauge has a lower set of lines for Zeniths and an upper set of lines for Webers.

For those who have not set float levels before, it is critical. I spend about 3-4 hours shimming and re-shimming the needle valves to get them near perfect.

This is the standard float gauge sold by Pelican - they're all the same.

kucharskimb · 02-03-2007, 09:55 PM

Yeah, that's the same one I have from PMO. PMO supplies Pelican.

But you make some bold statements. The only reason this is the standard gauge is because PMO is one of the only suppliers with items regularly in stock and he supplies most mail order houses. Richard said he's been selling this gauge for 25 years. By now, the market is flooded with them.

Additionally, the car will run with floats set incorrectly. And you may never realize it is running poorly. Float level affects things like transition to mains and upper end AFR. The main reason for this is the location of the holes in your emulsion tubes (high or low) and where the fuel level sits compared to those holes.

41mm is at the top of the PMO gauge and about to spill out.

Seems 35mm is the consensus. I told Bieker I would do some checking and get back with him with what I found out. Perhaps Bieker was having a mental block when looking at his gauge. But Bieker went through the trouble to have his gauges verified by Weber and then had them produced for resale.

Quite honestly, Bieker and Parr seem to butt heads quite often over tuning idiosyncrasies.

So, where is the disconnect on this issue between them?

horizontallyopp · 05-30-2011, 12:43 PM

This is the only reference I have been able to find about the Bieker gauge and instructions being incorrect. I have borrowed a Bieker gauge and have checked the 35 mm line (from center of float bowl opening to line) and my floats are low even compared to that, forget the 41 mm that Bieker has etched for the W4 Weber setting.

Thanks,
Keith

1QuickS · 05-30-2011, 01:35 PM

Porsche spec for fuel level is 20.75 +/- 1mm from top edge of Carb housing (w/o gasket) @ 3.5 psi fuel pressure. Distance from top of throttle body to where the gauge installs is 55 mm so distance up is (55-20.75) or 34.25 mm. (The 55mm dimension is the average of measurements taken from three throttle bodies.)

horizontallyopp · 05-30-2011, 04:39 PM

Thanks Paul - I've been studying your tuning directions religiously, but wasn't until I borrowed this Bieker gauge that led to this search, as your directions I assume are referring to a PMO/Weber gauge with the two upper lines.

My float levels seem to be really low, which is quite mystifying. More than just a shim or two. Not sure why that is.

1QuickS · 08:50 PM

Hi Keith,

After I "blueprint" floats I routinely use 0.090" thick shims under the needle valves. I've found (after 400+ float adjustments) that about 1% of the floats have nominal factory geometry. I built a gauge to adjust floats to the nominal geometry and the result is that most shims are within 0.010" of the nominal. By the way, 0.010" is approximately equivalent to the 2mm tolerance band of fuel levels I quoted in my previous posting.

I routinely receive Weber projects with uniform shims (usually a fiber shim of around 0.040" thickness) which leads me to believe most "finicky" Weber issues eminate from poor tuning. (PMO's utilize a window for viewing fuel levels which helps an average tuner get them right.) In addition, since 99% of all floats are non-uniform in geometry it follows that fuel levels in the four fuel wells are not uniform. This then means that the four main fuel deliveries are activated at different times during engine operation.

By the way, fuel levels must be set while engine is running, the vibration and the constant creeping open/closed action of the valve will settle out to an actual, running fuel level; bench setting is static and friction will mislead your adjustments. And yet another item to consider is the divot on the tongue of the float, this divot should be peened out (from the back side) and resurfaced to provide a fresh interface for the needle valve to rest on. Otherwise the needle may bind on the old divot location...I thought I was too anal here but did see the same recommendation in a Weber document.

Bench setting does have one benefit, it allows checking to see that the float geometry is close to design. If the tab on the float isn't perpendicular to the needle then the interface is sloped which can then result in erratic fuel levels or side loading of the needle which can cause stiction. Bench settings for the float are: top of float should be 12.5mm above top surface of throttle body (hold it in position with a bit of crushed newspaper lightly wedged between side of float and fuel well) and the tab should be 18mm below the top surface. If these dimensions aren't close then bend the tab on the float to get them in the ballpark, shimming fuel height using the PMO (or other equivalent) fuel level sight glass is the way to go.

I think that uniformity of fuel level is most important for consistent fuel delivery across the power band (within 1/2 a graduation of the two rings on the sight glass or about 0.005" shim variation) is adequate (use sandpaper on a thicker shim) but I don't have data to back it up. It is just that 0.005" shim thickness is relatively easy to adjust and any better is an accountant's task. Mindful that higher fuel levels tend to enrich the fuel delivery across the power range and conversely.

Thank you for the opportunity to air out this topic.

horizontallyopp · 05-31-2011, 11:10 AM

Many thanks Scott - my car has been sitting for 2 years while I swapped from the 914 based motor to a 69 911E motor, and would like to drive it this summer! I'm pretty sure I'll be in touch to book a slot for you to remanufacture these Webers for me, as they are not in great shape. I'd just like to get it running as well as I can to get me through the summer!