i have a small block 400 that is mostly stock. i had a popping at high rpms and someone here told me to check my ignition. i set my timing and checked my plugs(they were at .040) and are accel shorties. i re-set them to .032 but now i'm second guessing myself. which is correct? the popping did get better when i closed the gap but on-line it says to set these plugs at .035-.040 ) H E L P !!!
If you have less popping at .032 than at .040 on a mostly stock 400 engine (which won't have much compression) then either you fixed some kind of problem with the spark plugs--or--you have a substandard ignition system. If this is a HEI system, it should fire a .040 gap. If it's a point-style system, you shouldn't have a .040 gap.
First Guess: If this is an HEI, your coil is on the way out.
Get a calibrated spark tester and figure out whether your ignition has enough voltage capacity.