You need to set the float to the specified height. I have not worked on
that specific carb but you do not adjust the mixture ratio with the float
level on any carb. If it is running too rich then you can change the main
jets. First you should make sure that the carb is otherwise working
correctly. Normally carbs are pretty close to the right mixture to start
with. Suddenly having too much fuel suggests a problem, not an adjustment.

"Bill York" wrote in message
om...
I've got a 1978 mercury 470 i/o (170hp 4 cylinder) with what I think
is the Rocheseter 2bbl carb.

It was loading up on fuel after running for a wee bit. I've adjusted
the float but now I suspect it's too lean. (Drag)

I'd like to get a book to get this "just right" but I'm also looking
for any tips from someone who has worked with this type of carb.

Suggestions on how to tune this carb?

Bill