Dual Quad 318... I used a 273 intake

That seems like a real strange situation not having an open plenum underneath both carburetors. Mine I can rev the entire engine with each carburetor separately and I can tell if one's not performing up to par...(Jpar..)..:D..
well, you can on this too but the left front/rear barrel on the carb is feeding the left side of the engine and same for the right. I had it hooked to just the front carb and it idles and revs great (I didn't drive it like this). I noticed when I did it to the rear carb there was stumbling, so I was going to let the gas circulate through it and see if it comes out of it. If not, I'll have to take it apart and clean it/inspect it. No biggy