Float levels Weber 40 IDF / new EMPI HPMX 40's

[Phil West]

Does anyone know the correct float levels for these carbs?  The Dellorto DRLA 40 is (per the Superperformance book) 5 to 6 mm closed (i.e. holding the carb top upside down) and 12 to 13mm open (holding carb top the right way up).  Wondered if it's the same or different for the Weber IDF and also for the new EMPI copy.  Out of the box I have a set of HPMX and they are 5mm closed and 27mm open.

Cheers
Phil

[Sam K]

I just reset the float height on the IDF's in my Thing last week. According to the Haynes Webe manual. The spec is 10mm closed (upside down) and 32.5mm open.

[Phil West]

many thanks.  Clearly these are way off, right out of the box!

[GreenTom]

I just reset the float height on the IDF's in my Thing last week. According to the Haynes Webe manual. The spec is 10mm closed (upside down) and 32.5mm open.

not exacly. 10mm closed and those 10mm + 32,5mm so total from the surface of the gasket is 42,5 as I remember from the Bob Tomilson's weber manual.

once before racing (this year) I set the float at the exact values as in the book... and in the half of the track I ran out of the gas in the carbs... (and steal running 16,00 ET with no belt)
Afther that I moved the top open level to maximum... and the prblem was solved (didn't cut the "thing" but just bend it).
cheers Tom

[Phil West]

Hmmm..actually I found this diagram on the web which goes against a 42.5mm total drop which to be fair sounds a heck of a lot.  Clearly it's worked for you though

[Felix/DFL]

I even set them at 32,5mm no probs.42,5mm is to deep for the bowls

One notice to the Empi ones. I checked a set of 40`s for a friend and on both carbs the holding pins for the floats were loose!
The pin could fall out at one side...

I crushed the ends of the bolts to secure the pin in the cover as it is in the ital./span. IDF`s.

Take a look at that point.

[GreenTom]

photo of my B. Tomilson's manual


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[Phil West]

photo of my B. Tomilson's manual


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interesting indeed - 2 diagrams 2 different measurements.  Must be a typo in one of them!

[Torben Alstrup]

Old Italian IDF´s need 10/32 mm to work their best.
Spanish IDF´s needs 10 - 11 mm.
EMPI IDF´s usually needs 10 - 11 mm. But I have been "all over the place" with those, from 8 to 12 mm. to make them deliver properly. Mainly because of imprper drilled supply hole in the main circuit.
T

[Phil West]

I even set them at 32,5mm no probs.42,5mm is to deep for the bowls

One notice to the Empi ones. I checked a set of 40`s for a friend and on both carbs the holding pins for the floats were loose!
The pin could fall out at one side...

I crushed the ends of the bolts to secure the pin in the cover as it is in the ital./span. IDF`s.

Take a look at that point.

yeah I see what you mean.  Pin is loose in its slot so theoretically could drop out.  Cheers

[Phil West]

I even set them at 32,5mm no probs.42,5mm is to deep for the bowls

One notice to the Empi ones. I checked a set of 40`s for a friend and on both carbs the holding pins for the floats were loose!
The pin could fall out at one side...

I crushed the ends of the bolts to secure the pin in the cover as it is in the ital./span. IDF`s.

Take a look at that point.

I measured the float holding pin length to be 31.7mm (actually that's the measured length of what hole size would be needed for the pin to fall out one side).  The width of the carb recess where it sits is 30.5mm.  So in theory the pin has (only just!) enough to stop it falling out one side of its holder.  It's really close though - this is a spectacularly bad design.  Clearly the build quality of the EMPIs is not the same as the original carbs.  As you say that pin needs securing better than that.  I wasn't sure how to crush the ends of the cylindrical steel pin as there's only a tiny bit sticking out the end.  It does make me wonder if there's any other things like this on the EMPI carbs that are a concern.

Cheers

[Felix/DFL]

I even set them at 32,5mm no probs.42,5mm is to deep for the bowls

One notice to the Empi ones. I checked a set of 40`s for a friend and on both carbs the holding pins for the floats were loose!
The pin could fall out at one side...

I crushed the ends of the bolts to secure the pin in the cover as it is in the ital./span. IDF`s.

Take a look at that point.

I measured the float holding pin length to be 31.7mm (actually that's the measured length of what hole size would be needed for the pin to fall out one side).  The width of the carb recess where it sits is 30.5mm.  So in theory the pin has (only just!) enough to stop it falling out one side of its holder.  It's really close though - this is a spectacularly bad design.  Clearly the build quality of the EMPIs is not the same as the original carbs.  As you say that pin needs securing better than that.  I wasn't sure how to crush the ends of the cylindrical steel pin as there's only a tiny bit sticking out the end.  It does make me wonder if there's any other things like this on the EMPI carbs that are a concern.

Cheers

Hi Phil,

I droped the pin out and hammered one end flat on my workbench. Then install until it`s getting thight. Finished.
There was another problem on the 40`s I checked. One srew for holding the acceleration nozzle didn`t want to come out. Itwas very tight when I wanted to get it out. So I backed it in again.
Sidenote: The venturis from the ital/span. ones doesn`t fit...
Otherwise the carbs were ok and behave very well on an 1914cc engine.

[Phil West]

I even set them at 32,5mm no probs.42,5mm is to deep for the bowls

One notice to the Empi ones. I checked a set of 40`s for a friend and on both carbs the holding pins for the floats were loose!
The pin could fall out at one side...

I crushed the ends of the bolts to secure the pin in the cover as it is in the ital./span. IDF`s.

Take a look at that point.

I measured the float holding pin length to be 31.7mm (actually that's the measured length of what hole size would be needed for the pin to fall out one side).  The width of the carb recess where it sits is 30.5mm.  So in theory the pin has (only just!) enough to stop it falling out one side of its holder.  It's really close though - this is a spectacularly bad design.  Clearly the build quality of the EMPIs is not the same as the original carbs.  As you say that pin needs securing better than that.  I wasn't sure how to crush the ends of the cylindrical steel pin as there's only a tiny bit sticking out the end.  It does make me wonder if there's any other things like this on the EMPI carbs that are a concern.

Cheers

Hi Phil,

I droped the pin out and hammered one end flat on my workbench. Then install until it`s getting thight. Finished.
There was another problem on the 40`s I checked. One srew for holding the acceleration nozzle didn`t want to come out. Itwas very tight when I wanted to get it out. So I backed it in again.
Sidenote: The venturis from the ital/span. ones doesn`t fit...
Otherwise the carbs were ok and behave very well on an 1914cc engine.

Yep I found that too - I got vents from the 44idf which evidently the body of the empi 40 is made from.  Also one of the pump jets (grey metal) had flashing around the jet hole that made that jet much smaller than the others.  None of the jet sizes properly matched up to my jet guage, all up to .3mm off.  Finally an air jet in the main stack was not drilled through in the final drill pass so was much smaller than all the other jets.