Oly
thanks for reply
I am a new guy and thought I would be ignored.
Just insecure i guess but goes to show how good this forum is.

Now to the point I have a Carter YF I cant identify. the bowl is not cast is has x2207
the base is cast and has a 1-830 on it.
I have looked several times and it could possibly be 1-630 but I think it is 1-830
It is not marked the same way as a W-1 with
a recessed # in the cast bowl.
So I could use help on identifing this YF carb.

Now to the original problem on the difference between a 37-40 and a 41-48 W1 with the same cast # on it is what I needed to know.
I found that answer the 37-40 is not vented . the 41-48 is vented with a accelerator rod running upward.
The 49 and up have an additional rod running upward for the choke.
This is what it took me all day to find out.
Now I am ready to see if the experienced agree or not.
And Oly I need identy on the YF
Thanks
Su per long huh??