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318 carb question

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opeaseasilverton

New member
"I was having some issues the

"I was having some issues the weekend getting the starboard engine up to RPMs at WOT under load. I checked tonight and the butterfly valve was not opening all the so I fixed that. However, it does have a 4 barrel carb and under no circumstance could I get the two furthest ports from the flywheel to engage, open, or put out any fuel. Do I have to be under load to create the vacuum to open these? Or did this last owner tighten them down to save gas? Any ideas on where to go from here to ensure they both work and are adjusted correctly?

Thanks,

Scott"
 
"Scott, I'm not sure which

"Scott, I'm not sure which carb you have but I had a similar problem with mine. I have a carter AFB. The two ports fartherest from the flywheel on mine are the main ports. At one time the 4 barrel would not open. I could take a screwdriver and push on them and still nothing. Turned out to be a bent linkage. As the throttle is pushed forward the main butterflies open and when they reach a certain point a spring assisted linkage pushes open the 4 bbls. I straightened that out and still every once in while I wouldn't get the 4bbl to open. Found out then that there was a groove worn in the throat where the butterflies rested. Sometimes they would hang in that groove. I took a little emery cloth and dressed that up and have had no more problems."
 
"Billy,

The two closest to

"Billy,

The two closest to the flywheel are the only ones working. I looked at all the linkage and couldn't find any mechanical piece that moving the linkage would result in a movement. It would move by hand but nothing else. I'm almost wondering if it would be better just to have them rebuilt so I know what I'm working with. I did talk to a few of the other twin screw owners and one has 318s and they stated that the same issue happened on their boat. He stated that there is a screw that is attached to a spring and it can be adjusted to either tighten, which limits them opening, or loosens the spring to allow them to open more freely. Yet another person said that it is vacuum controlled. I have no idea what is going on with these carbs but I appreciated the feedback and I will look to see if I have a similar set up to what you have.

Thanks,

Scott"
 
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