SU Carb problem

[Eric Rupert <rupert@rpm.com>]

Any thoughts on this?

I have a '66 Spitfire w/ standard SU HS2's.  I have completely rebuilt them 
with new floats, gaskets, jets, etc.  I purchased new Grose Jets and to 
replace the needle and seat setup.

The problem is, when I hit 60mph gas starts pouring out of the vent of the 
front fuel bowl.  I think it's a pressure problem since I seems to be 
driven by engine RPM.

Any thoughts?