When hot the carb overflows slightly, enough to flood. What is the best needle and seat for that carb? Fuel pressure is less than 2lbs, mechanical pump
Thanks

1956 F100 272 4 speed
Northern California

Add a 1/4” or 3/8” phenolic spacer under the carb and if possible the truck intake gaskets that blocks 1/2 of the manifold heat to the intake. . Has the front exhaust crossover been removed and you have dual exhaust? 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

My old '60 F100 had a hot starting issue (had headers).  It took me a long time to figure it out but there was no way for any heat to get out from the engine compartment- just tiny little holes in the inner fenders.  Not that it is your problem, but keep it in the back of your mind as a last resort if nothing else works.  

Thanks guys,  that makes sense about the heat thing, there is a 1/4 inch spacer there but it looks more like gasket material.  Would a phenolic spacer conduct less heat?

1956 F100 272 4 speed
Northern California

They have been used in the electrical industry for 100 years for insulation and heat dissipation. I had one 3/8” under a Carter WCFB small base carb on an “A” intake that boiled the gas in the carb when it turned it off. It had a cast iron base which held the heat. Stopped the problem. I now use 1 under each of the carbs of my dual quad unit. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Holley (and maybe others) also make thicker gaskets that are supposed to insulate against heat.  Not sure if they make it for a 2100, though.  They're about 1/4" thick or so.  

That could be what's under the carburetor now, it's about 1/4 inch thick and the gas still boils

1956 F100 272 4 speed
Northern California