Re: 1976/77 OMC 9.9 & 15 carb needle valve bearing

[Don]

Well, first, are you working on a 76 15hp, or a 77 9.9hp? I guess it does not make much difference carb wise though. The engine idled OK before the carb job, correct? I guess I’m wondering why you pulled the carb apart if it was idling OK. In any event, it won’t idle now….Does it seem too rich, or too lean….Will feathering the choke help it idle? Or, if it is too rich, perhaps you can turn the needle valve almost closed without it leaning out much.
There is the possibility that something else went wrong while doing the carb work, although that doesn’t seem likely. I guess the simplest thing to do would be to try a different known good carb….
I can’t imagine it would do any harm to add one of the cup seals on a carb that was not equipped with it originally, but who knows….Perhaps the cup seal is covering/blocking a fuel/air passage messing up the idle. So, I think it best to try peeking inside to ensure the cup seal is properly installed….If so, go ahead and remove it, then try running again….I suppose it is possible that someone installed a newer carb on this engine….
Let us know, this IS an interesting topic, sure hope we can get some clarification on the cup/seal usage…