I'm working with a holley 650 DP and I'm having some transitional throttle issues, so I'm pretty sure its something with the acclerator pump system. Stock jetting was 67/73, car felt kinda flat and down on power, plus I had just swapped to a better exhaust system, figuring it was lean I started jetting up. I worked up to 70/76 jets, with stock pump cams (yellow in rear I think), rear pump is 50cc, 28/31 shooters. Car ran well and picked up some good power, but was a little rich all the time and had a stumble(sounded like a 2 step when going down a hill) if I even thought about backing off the throttle while going down the road. Anyway, tried a few things, now I have 31/31 shooters, 65/73 jets, stock pump cams. The car has a slight bog before the secondaries open, then when they open it stumbles slightly, then takes off like an ape with rabies. Full throttle performance seems to be as good as it was with the 70/76 jetting, but this is just seat of the pants. I haven't had a chance to take it to the track with the smaller jets. Ideas? I have a pump cam assortment, jet assortment, a 28 shooter, 2 31 shooters, and a 35 shooter to tune with. Engine is a 10:1 306, stock 351 D0OE heads, crane energizer 284H (228 at .050, .512 lift, 112 CL), stealth intake, hooker comps, C4 w/ 3500 stall, 3.70 gears. Last time I went to the track I was running consistent 8.42's in the 1/8th, with the 70/76 jets and 28/31 shooters. So I think it was running pretty good, but then again, full throttle runs aren't much of an indicator of accelerator pump tuning. Where should I start with this? I'm thinking of going ahead and doing some pump cam swapping and adjusting the screw holes to see if that clears it up. Can anybody give me a little guidance here, or is it all just a matter of experimentation?