What's the purpose of the venturi lock screw? Don't say to lock the venturi. In a classic example of my lack of observation skills I realised that I have the nice little pointy ended one in the left hand carb of my 1800, but the right hand side... well it had a tinware screw in it. You know the sort with the little cutting in the thread for scraping up gunk? One of them. On that same carby I also noticed that the choke butterfly stop screw that protrudes into the throat is some kind of countersunk head bolt from a hardware store, which would probably mean an imperial thread. Eeee!

I pulled out the tinware screw and screwed in a new flat ended HT bolt. Not optimal, but the cutaway in the thread couldn't have been helping things. So, would the completely wrong type of screw be messing with things?

Thanks.

they hold the tube in place thats all but thats enough

Right, so the reason it is a grub screw (Did I actually remember the terminology for a change?) is to clamp the tube. Well it has never moved so I guess it'll do. I have a funny 30PICT, or something like it that I pulled off my S beetle years ago. I'll see if it has a compatible screw on it when I get the time.

That carby I removed had a stack of vacuum lines that were blanked and an adapter plate so it could fit on the T tube. I still don't get why anyone would go to so much trouble to fit a smaller carburettor to it.

Thanks for the answer by the way.

Tristan the beetie single solex carbs have pressed in vents
so no grub screw on them

Oh well. Guess I can use it to throw at the neighbours cats or something then