Drag tuning question

I was wondering if a carb spacer would lower 1/4 et or raise it?? The people who owned my stang befor me said they had it into the 14's and I cant break 15.2. I put the spacer on a while ago when I bought the car and felt an increase in torque. But every run I do with my G-tec I get as low as 15.2. I have a 68 fastback with a 289, dual plane manifold with a 650 carb. Goin to the track on wensday and would like to break into 14's.
Any help appriciated.

I never really thought of that, thanks. To keep my car from stalling out my launch isnt 100% so I doubt the g-tec kicks in then.