I've searched on here but thought I'd start a new thread to see what everyone's thoughts are for my situation. This is a BBC 12° head deal, 14-71 HH, setback rotors, four blade hat. It idles stable in natural, but as soon as I put it in gear it surges enough to make staging a challenge. I've tried curing this by adjusting the BV without any success. That being said I do have a fuel distribution issue at idle. Numbers 1-2 are very fat at idle and the rears are hot and lean, so I can't richen the BV any more without causing #2 to go out at idle, if I lean it the rear cylinders will be over 1000° at idle. Not sure if this is causing the surge or not. The throttle blades are at .012 and both stops are contacting solidly, so there is no twist of the shaft. At WOT the fuel distribution is not a problem, the plugs are very even front to rear with very little stagger in the port nozzles. I only have the blower at 13% OD, but it does make 27# and I don't really have the need or want to run more boost or OD.