No! That is the square ore carb even though your measuring a bigger secondary side. It is the big offset for a spreadbore.
It also doesn’t need an adapter on the ‘68-340 intake unless the butterfly’s won’t open fully. Or your also missing the thick gasket.
If your carb is boiling off fuel after a few minutes you have a serious issue and start with YellowRoses heat block off plates between the head and intake.
Secondly, use the OE type THICK gasket. They are about.333 thick, give or take. There that thick stock because of the problem your having.
Next is to double check float levels, lean/rich conditions.
And sorry Holley lovers, even the fuel bowls can have fuel boiled away on the Holley’s. That’s also why the aftermarket sells heat shields for them.
View attachment 1715412331This is the 4611s I have. Isn't this a spread bore? Also I have this on a OEM 68 340 Cast Iron Intake, Bores match. The plate (adapter) i have is just a heat sync plate, not spread to square.
