<VV> Carbs again

[Norman C. Witte]

This is on the '65 Corsa 140.  FIrst, a recap on what I have done lately. I
added vent tubes to all four carbs and changed the 54 jets in the primaries
for 52s.  Now I seem to have a rough idle, and when I pop the throttle and
let go of it quickly, I get a backfire on the left side.  The rough running
seems to come from the left side, too.  I did also change plugs, and it
looks like all the plugs are plugged in.

Ideas?

Klueless Norm