Vented / non vented linkert Venturis !

[dirtyss]

There are a couple of questions I would like to ask regarding the venturis used in linkerts.

1) I have noticed that the annular air groove that is machined on the ID of the venturi can be of different width. Generally (but not always) it appears that non vented venturis have a narrower air groove approx. 3/8" wide compared to the vented venturi with approx. 5/8" wide annular air groove. Is there a reason for this ?

2) Is the slot machined in the rim of the venturi to provide the vent in the internally vented linkert a critical size ? The externally vented linkerts appear to use a specifically sized hole in the side of the body of around 0.188". I am aware that the air passing through the vent is for supplying air to the nozzle to mix with fuel and emulsify the mixture as throttle opening increases. I have read somewhere that if the hole/vent size is altered the emulsifying process is altered, but I cannot figure out why this would be the case.

The main reason for asking these questions, is could I modify an externally vented venturi with a narrow annular air groove by filing a slot in it and thus convert it into an internally vented venturi.

Regards
Paul

[T. Cotten]

Paul!

By any chance did you log the models and their differences?

Many thanks if you did!

H-D models varied by restricting their side vents 'mid' '48 or so, and it seemed futile enough to return to the "more is better" approach for the later productions.
And at least one model varied with a 'deeper' annular groove, as attached.

So yes, as long as you have an "air correction" vent, it will run!

....Cotten

[dirtyss]

Thanks Tom

Unfortunately for us - on this side of the pond, finding any carbs that have not been messed with would be a nothing short of a miracle and so my venturi differences are noted from pictures of parts on suppliers websites, reference literature and the ones that I pull from carbs that they should not be fitted too !

I'm on my 3rd M344 carb strip down and surprise! surprise! it has a Bonneville venturi in it again, along with the wrong nozzle fitted (same as the previous 2) pulled from stock 74" Chiefs. I had run out of internally vented 1 1/16" venturis but had a couple of non vented ones - hence the questions.

Always appreciate your Knowledge and advice.

Regards
Paul