Edelbrock flooding w/o noticeable cause

[luvbowties]

Working on a customer's car with a 1963 327/250hp/stock. He has used a metal adapter to run a rebuilt, via NAPA, Edelbrock on the factory intake. The 250hp had smaller-bore intake with 4GC (?) carb. The 300 hp used a larger-bore intake with AFB(virtually identical to today's Edelbrock). His adapter fits well on both intake and on carb base. When not flooding, the carb-and-engine perform like new, from very slow driving even in 4th gear(4-speed Muncie) thru 120++(many of the +'s: speedo only registers 120).

At times, the carb floods(runs over top of carb and down the sides onto intake) with no apparent cause. I've driven it until it flooded, and quickly removed the tabs that hold the needles down into the jets, suspecting 1 or more needles having being raised too much and failing to re-enter jet; both were in correct position. Removed top for inspection: all correct. [NEEDLE AND SEAT HAVE BEEN CHANGED SEVERAL TIMES.] By time I re-assembled and started back up, it will run again, perfectly with no more issues for next 40-50 miles. Tried adjusting float level, new floats, rebuild kit, and no go. Fuel pressure via mech pump is normal for the carb, a bit low for original carb spec'ns. I seem to recall the Edel's and AFB's run better with around the 4-5 psi this pump produces???

My theory is the carb is simply getting too hot and boiling the fuel in the bowl, causing it to expand and flood. Anybody had a similar problem? I've tho't of changing the adapter to a phenolic or some material other than aluminum; or maybe even using a heat spreader/separator/dissipator plate. The flooding seems to follow no pattern, such as just after a wot-session, a sudden stop, slow-driving or fast-driving sessions. BTW: the orig. carb NEVER malfunctions. And the Edel NEVER floods when cold, such as soon after 1st daily startup--always after engine has been up to operating temp for a time.

Will appreciate any known solutions or even ideas and theories.

Anyone else think the heating could be the source?

Thanks to all.
Sam