So my bbc has a strange little stumble that I'm having issues diagnosing. Base timing is set at 14 and total advance is 35 The stumble is present when I first take off and again just as the secondaries open. The carb is a Holley 750DP. I first started out with 74/80 jets and a #55 power valve. Now I'm at 77/81 jets and a #65 power valve. The problem is still there but it's about 75% better. I pulled some plugs today and it looks like the motor might be running a bit on the lean side. The plug color is like a light gray and nowhere near the white when I first started running the boat. The ignition system is all new and fuel pressure is within specs. Any ideas? I was thinking of maybe going back down to a #55 power valve and increasing the primary jets by one. Also, the timing at 14 has me kinda nervous since factory spec calls for a base of 10 If I bring the timing down from 14 to 12 my total advance ends up at 33 which is good but then the stumble off idle is more noticeable. I know that I should probably send the carb to get dialed in by an expert, but w/ a baby on the way I'm on a tighter budget. My current setup is as follows: Close to stock cam (I verified this by taking vacuum readings) square port cast heads, Victor Jr intake, Holley 750DP w/ shaved choke horn. The ignition system is dialed in. I completely rebuilt the dizzy and the external coil and MSD box are not that old.