Vacuum Tuning

Every once in a while I come up against something like that:The engine likes a ton of initial, but likes less on tip-in. So it becomes a compromise.
-However, a lot of times its just the A/F ratio.Whats your idle speed? Are you running a PCV system?
-The position of the primary butterfly may not be syncronized to the idle transfer port.This is kinda critical.I usually take the carb off, flip it upside down, and eyeball it.I adjust the curb idle screw such that the idle transfer port is just peaking out on the manifold side.Then I close the secondaries completely.Then put the carb back on.From this point, I set the idle speed by manipulating the initial timing, or the secondary cracking screw, or occasionally, the float level.I leave that curb idle screw alone as long as possible.If I do adjust it I take a careful note of where it is before I move it, so I can get back to it if I need to.
-If the idle transfer port isnt syncronized, you will get tip-in problems.Im assuming your carb has idle feed circuits to the secondary side. If youre not using the PCV system, it gets harder to get enough idle air. That cam likes idle air.At least in my experience.
-As to the timing. I like a little less initial, and like to start bringing it in just off idle to maybe a couple of hundred above.Same goes for the vacuum advance; bring it in as fast as she will take it. It will vastly improve your driveaway.Just make sure that every thing drops out at idle.
-When I was running the 292/509 cam I had to build a 2-stage curve to run 87/E-10.I had to slow it down a bit, beginning around 2500.So it was fast in, then slow out, topping out around 3600.But I still brought a ton in with the can, and as fast as I could. Smoothes her out and makes some good torque.
-Happy tuning