The parts book is confusing as to where one might think it was installed with the CA72/77 and the CB72/77, CL72/77 carbs.
So far I've had in hand somewhere around 250+- CB72/77, CL72/77 and 40+- CA72/77 and something I noticed back around 1994 when I worked on the first CA72/77 carbs and since is that those carbs (the ones I've had in hand) had the air screw with the wide shallow slot near the top and no "O" ring.
That said I've never seen a CB72/77, CL72/77 carb with that design.
If someone suspects a leak at that air screw you can "while the engine is idling" cover the screw head with your finger or drip fuel on it. . ....................lm
DianneB wrote:That's interesting Brew.
On the air screw without an O-ring groove, was an O-ring used under the spring, around the round shank?