Sounds like fuel to me too bro. Did ya yank the plugs at all and see if it was lean/fat? I'm guessing fat. Remember, fat is safe, but lean is fast.
Still running a duraspark ditzy? Get a good light and see when/how much timing it's throwing in. Sometimes (mine included) those things are goofy with the advance. Unlpug and block off the vaccuum advance at the track, set the base timing, and LEAVE the vacuum advance disconnected. Check the plugs, adjust the jets accordingly. No power valves, right? Didn't we already get rid of those?
Did the car feel like it nosed over? You were already losing ponies at half track. Launching that hard, ya definitely need jet extensions in the rear, and center hung floats.
Don't get freaked out bro, it's just a weather and tuning issue. I made you a promise, and I intend on keeping it!!!
