[DeTomaso] NPC-Carb boiling fuel?

[Tom Di Iulio]

Hi all,
 I have a friend with a 69 chevelle, 350 with holley (new) 650 dbl
pumper, mechanical secondaries. After the car has warmed up, the carb
will frequently barf up fuel thru the front air horn. This does not
happen with the back bowl. The carb bowls are not so hot that you can't
touch them, they're relatively cool at the time so we're confused about
advice regarding boiling fuel. It's as if the fuel is being pushed from
the electrical fuel pump straight thru the carb, forming a mini-geyser
at the front. Doesn't happen all the time but enough where driving the
car is a dicey proposition.  
Any thoughts or advice? Thanks
Tom Di Iulio
Denver, CO