"My M440 would idle, but not a
"My M440 would idle, but not as nice as I wanted, and it made it hard to dock sometimes. Taking advice from this group, I tried to use a vacuum gauge to set low speed mixture on my Carter AFB carb, although I was certain that I had it pretty close already. Well, there's a reason you're supposed to use a vacuum gage, I discovered! Adjusting for max vacuum, I was lean on one side, rich on the other, but the tach never changed by more than a tiny bit. And it’s hard to judge by “rough running” because the engine is hard-mounted to the boat and cant shimmy like a car engine when it runs rough. But the vacuum gage changed by several inches of mercury as I fiddled with the mixture screws. Once adjusted for max vacuum, it idles nice now. (And I was certain I had it close!) I found that I could use the vacuum source for the choke on the Carter AFB, because when it’s warmed up, (and it should be) the choke stays open even without vacuum connected to it. Using PCV vacuum does not work well, because it interferes with the basic low speed mixture if you disconnect it. Vacuum gage: $18. Smooth Idle when docking: Priceless. }"
"My M440 would idle, but not as nice as I wanted, and it made it hard to dock sometimes. Taking advice from this group, I tried to use a vacuum gauge to set low speed mixture on my Carter AFB carb, although I was certain that I had it pretty close already. Well, there's a reason you're supposed to use a vacuum gage, I discovered! Adjusting for max vacuum, I was lean on one side, rich on the other, but the tach never changed by more than a tiny bit. And it’s hard to judge by “rough running” because the engine is hard-mounted to the boat and cant shimmy like a car engine when it runs rough. But the vacuum gage changed by several inches of mercury as I fiddled with the mixture screws. Once adjusted for max vacuum, it idles nice now. (And I was certain I had it close!) I found that I could use the vacuum source for the choke on the Carter AFB, because when it’s warmed up, (and it should be) the choke stays open even without vacuum connected to it. Using PCV vacuum does not work well, because it interferes with the basic low speed mixture if you disconnect it. Vacuum gage: $18. Smooth Idle when docking: Priceless. }"
