On the Ford 2150 2 bbl carburetor how can I convert the main jet size (e.g. #57, 59, 63, etc.) to a diameter in inches? I have some main jets that are not marked and would like to drill them to a #65 size, but I don't know the drill diameter that equates to a #65 jet size.

 

Do not re-drill carb jets. The shape or profile of the entry and exit points of the hole are very important and a regular drill will not work properly.

 

Roger that. I will not drill the jets. I am finding out the jets are sized with some type of flow bench.
Thanks.