Dellorto carbs. WTF is this?

On the side of the carb there are 2 ports for bunging your meter on
Next to them blanked off adjustment screws
Next to them the mixture screws.

Above each of them is a large diameter cross head blanking screw with the sides of the thread cut off.
If one takes it out and looks into the holes There are 5 small holes in a zig-zag pattern, behind which I can see the choke plate. These are the progression holes yah? Above looking at the outside of the carb there must be a passage leading to it.
So why have these blanking screws with part missing thread and no o-ring or other seals? They must have a purpose.

 

Progression blanking screw. No seal on the part diagram.

 

Are you actually talking to yourself live on a forum? I've heard of thinking out loud, but this is a step too far!

 

Don't disturb him. He's thinking.

 

Answering my own question to save anyone researching
I'm still not satisfied but I realised you lot wouldn't have a clue so I've posted on Vzi too.

 

That is so condescending and rude, I know perfectly well what a 'carb' is and protein. I know all the main food groups.

 

I'm not answering now.....


I could have helped......

 

i couldnt! havent a clue lolol

 

Or go on Vzi and tell him to F**k off, you can swear on there

 

I can't now you've said it, you'll all find out my Vzi username!

 

I better go and have a look...

 

They don't know either I reckon but at least nobody's told me to F**k off yet.

 

Would you people stop with the Vzi language please

 

According to my book it is called the"progressive drillings cover" so looks like Vzi are right, the hole is used to make the drillings?

 

So why not then plugged after like every other carb? I guessed it was for manufacture, I thought that was a given and not the question. Why flat off the sides of the thread on the plug/cover for starters? Why have the thread stop short of the head and a groove that looks good for an o-ring.
I have a bee in my bonnet I want answers!

 

The thing is, they lead straight to the progression holes, there's no seal other then doing them up tight and I wondered...
1) what would happen if air leaked in here due to bad seal
2) might they be designed specifically so you can bleed some air in?
3) why would you want to do that?
@Top Banana Racing knows about this sort of thing I reckon.

 

If you can't understand the question without pictures, I doubt you'd know the answer, but so that you can get some enjoyment from the thread when you look back to see why I quoted you, here's a fluffy bunny.

 

Maybe the flats angle/adjust the air, the flats on the cover would show you the angle of the flats on the thread?

 

This thread is now worthless with a picture! Ugly bunny.