1963 Johnson 3hp carburetor setup

[beruken]

I have the service manual for a johnson jw-18 3hp and noticed the bottom of the carburetor has a high speed adjustment screw but on my carburetor it seems to be disabled with a some kind of false set screw or the needle side and adjustment sides were cut off.Any reasons for this?

K.

 

[Chinewalker]

Sounds like you might have a fixed high speed on that carb. They phased out the adjustable high speed jets on the 3s in the 1960s.

 

[beruken]

Thanks!

 

[F_R]

An "orifice plug" behind that plug meters the high speed fuel. It has a precision hole through it. Don't damage that precision orifice with drills or wires, etc. And it requires a special screwdriver to remove it (usually).