Model Engine Company of America
Closing a Bell Mouthed Spray Bar.

This requires above average skill level.


What causes that problem is the end of the spray bar is bell mouthed. The tapered idle needle is in too far so metering is not proper.

You can adjust it by coining the end closed. You can use a flat end punch tap slightly tap the end of the spray bar while the opposite side is flat against a steel block.

You want to close the hole until the tip if the idle needle jut fits in the end of the spray bar about .030" . Then try running the engine. If its too rich right above idle increase the size of the which can be done by pushing the idle needle into the spray bar slightly to bell mouth it again but not to the degree prior to coining it down.


The above information is provided as a guide. Since MECOA/K&B has no way of determining
the ability of the individual using and understanding this information, we assume absolutely
NO RESPONSIBILITY for any damage to person or property from the use of this information.

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