What about 4-corner idle on a BBC 454, hydraulic roller 218/226 @.0502, 112 lc, mid-500 lift? One person advised a good starting point is all 4 screws open 1/2 turn, another suggested 1 turn. I have just set the timing (total 38 deg) which is where the best dyno results were, and 1/2 turn seems better than a whole turn. Guess I'll have to get the vacuum gauge back on it. Do you turn one primary screw to get best vacuum, then do the other 3 the same? I'm assuming they should all be more or less even?
Chris