I've read several articles on setting ignition timing on a SBC and I am somewhat confused on the best course of action to take. My 406 SBC has a stock vacuum advance on a stock HEI distributor. The ignition timing set at 4 degrees BTDC, ( The engine is just built for low rpm torque: Small cam, quadrajet carb, longer rods, balanced, blueprinted, stock heads, 9.5:1 compression...not too modified.) It runs quite strong, but does have a dead spot right when I stomp on it (bad accelerator pump?) Questions, 1. If I replace the stock vacuum advance on the distributor and put on an adjustable one, and push the initial timing up to 14 degrees or so, will that help or hurt fuel mileage? 2. Is it worth the effort and cost on a low RPM engine? Will l see any performance gain? 3. Should I replace the mechanical advance springs and module as well? 3. If it is all worth it, what are the best numbers to set the initial and total timing at? Thanks.