Chimney cap clearance?

[AnalogKid]

Is there a minimum distance in which the bottom side of a chimney cap must be from the top of the flue? I have a cap with 8" tall sides. The flue extends past the chimney crown 3".

This will net me 5" between flue and cap, is that enough?

Thanks.

 

[shawng111]

That actually reflects my setup pretty well and i've never had an issue. I think IMO that it would be fine