Weber upgrade kit??

[Neil Bardsley]

https://www.cbperformance.com/product-p/6456.htm

Has anyone one use this upgrade kit. It replaces the mini Venturi with a round bar with several holes in it. Claiming that it improves airflow and mixture of air/fuel. The reviews on VW forums seem to indicate not much improvement before 5000rpm.

https://www.google.com/imgres?imgurl=ht ... STnbZL6PzM

I don't understand why I cant, buy some new aux Venturi, for far less. Cut the Venturi off in the middle. Leaving the support struts. Maybe leave some metal so the supports are connected. Then drill some holes in the bottom of the support struts for additional air/fuel mixture. I should get better air flow for less cost?

[Olivier Auvray]

Just let me know why, Weber (or others), spent a lot of money to make different atomizer (length & diameter)?

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[John Clarke]

Hi Neil
We run the 616/40 912 engine in the 356 Coupe with 'Spray Bars' on Dellorto 40 DRLAs with 34 mm Vents , 160 Air Correctors Running with 86mm Shasta Barrels and Pistons.
We also have the Raised Idle Jets (57)
Nothing to compare with, as I haven't run with any other Carb combinations .
Good Idle ,No Flat Spots and good Top End from 3000 rpm ..
But am having problems with the Ethanol degrading the rubber O Rings on the raised idle towers.
Not sure if Your Idea would work on the Weber IDF aux vents
Cheers Jay

[Al Zim]

With the advent of ethanol free gas available we ALWAYS return the customers 356 with the ethanol free gasoline. I have posted in the Ethanol section about this. Specially if your car is in storage. Look at you fuel tank carefully a leak can set your house on fire. al zim

[Neil Bardsley]

Hi Neil
We run the 616/40 912 engine in the 356 Coupe with 'Spray Bars' on Dellorto 40 DRLAs with 34 mm Vents , 160 Air Correctors Running with 86mm Shasta Barrels and Pistons.
We also have the Raised Idle Jets (57)
Nothing to compare with, as I haven't run with any other Carb combinations .
Good Idle ,No Flat Spots and good Top End from 3000 rpm ..
But am having problems with the Ethanol degrading the rubber O Rings on the raised idle towers.
Not sure if Your Idea would work on the Weber IDF aux vents
Cheers Jay

Thank you

By raises idle jet do you mean the jet doctor pipe connected to the air intake? If so I have these on my 914 as the idle jets kept clogging

[Neil Bardsley]

Just let me know why, Weber (or others), spent a lot of money to make different atomizer (length & diameter)?

CL-5d4efc447c73d4.59412449.jpg

images (1).jpg

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Sorry Oliver I don't understand if this is a question or statement?

[C J Murray]

Weber knows more about designing a carburetor than Uncle Ralph's Buggy Emporium, or you.

[Harlan Halsey]

+1 And you can substitute many combinations for "Weber and carburetor" .

[John Clarke]

Yes Neil the original small air intakes for the Idle Jets gets Plugged ( I used Stainless steel Grub Screws on the Dellortos) The air feed to the idle jet enter via the hollow raised towers. Reducing the chance of blocked Idle Jet.
And Ref the Spray Bars, instead of the atomised fuel entering via the Aux Vent
It enters via a hollow horizontal Spray Bar with a series of holes spreading the mixture flow . The concept of spray bars is old, and I believe was developed for airplanes .
Jay

[Olivier Auvray]

Weber knows more about designing a carburetor than Uncle Ralph's Buggy Emporium, or you.

KNEW would be better than KNOWS

[Olivier Auvray]

Just let me know why, Weber (or others), spent a lot of money to make different atomizer (length & diameter)?

CL-5d4efc447c73d4.59412449.jpg

images (1).jpg

images.jpg

Sorry Oliver I don't understand if this is a question or statement?

This is a question.

This is the answer:

More or less, the lowest end of the atomizer must be in the venturi for a value of 1/3 of the venturi size. This is the area where the vacuum is the highest inside the carburetor.
example: if venturi = 30mm , the lowest end must be 10 mm into the Venturi. You can check it

The highest end of the atomizer and the diameter of the atomizer must be correctly sized to ensure a constant flow inside the tube of the atomizer. It gives the atomizer non sensitive to reverse pulse from the intake.

In my opinion the "shower" bar can't do this.

[C J Murray]

Just let me know why, Weber (or others), spent a lot of money to make different atomizer (length & diameter)?

CL-5d4efc447c73d4.59412449.jpg

images (1).jpg

images.jpg

Sorry Oliver I don't understand if this is a question or statement?

This is a question.

This is the answer:

More or less, the lowest end of the atomizer must be in the venturi for a value of 1/3 of the venturi size. This this the area where the vacuum is the highest inside the carburetor.
example: if venturi = 30mm , the lowest end must be 10 mm into the Venturi. You can check it

The highest end of the atomizer and the diameter of the atomizer must correctly sized to ensure a constant flow inside the tube of the atomizer. It gives the atomizer non sensitive to reverse pulse from the intake.

In my opinion the "shower" bar can't do this.

Correct!

[John Clarke]

It's Amazing How Well The Spray Bars Work on the DRLA Dellortos when they are located high up in the Main Vents !
Regards Jay

[Neil Bardsley]

Just let me know why, Weber (or others), spent a lot of money to make different atomizer (length & diameter)?

CL-5d4efc447c73d4.59412449.jpg

images (1).jpg

images.jpg

Sorry Oliver I don't understand if this is a question or statement?

This is a question.

This is the answer:

More or less, the lowest end of the atomizer must be in the venturi for a value of 1/3 of the venturi size. This this the area where the vacuum is the highest inside the carburetor.
example: if venturi = 30mm , the lowest end must be 10 mm into the Venturi. You can check it

The highest end of the atomizer and the diameter of the atomizer must correctly sized to ensure a constant flow inside the tube of the atomizer. It gives the atomizer non sensitive to reverse pulse from the intake.

In my opinion the "shower" bar can't do this.

Thank you for you response. I understand better now.

[Neil Bardsley]

No facts but an interesting discussion on double venturi here. In summary the second small venturi creates more pressure which causes better atomisation.

https://www.rcuniverse.com/forum/glow-e ... print.html