Mercury 9.8 carburetor Question

[geary]

Guys,    While we were working on a small Merc 9.8hp, and cleaning the carburetor we noticed a small hole drilled thru the throat of the carb. just ahead of the flange on the port side of the carb that bolts to the manifold. The model of the carb is a Tillotson KB5A !  Our question is why is this hole there, it appears it would lean out the mixture of the idle circuit but not effect the his speed that much ?   If anyone has an idea why this was done, we would like to know ?

[seakaye12]

This subject was brought up on the Mercury board at one point.  Someone there said it was done to improve idle quality.  Not sure how factual that is but there’s a lot of knowledge over there;  just like here.

[crosbyman]

should be easy to check  idle performance out with a finger or without a finger

Joining AOMCI has priviledges 🙂

[billw]

Not sure how, when or why these holes came to be, but they are definitely factory and nothing to worry about. I have seen them a lot.

Long live American manufacturing!

[Author]

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