[njsteve]

It is very easy to mix up #5 and #7 since they are next to each other in the firing order, and on the cap. The car will run slightly off from the resulting wrong order of firing.

When they talk of the distributor being a "few teeth off", it means it was installed in a position that the distributor base and the vacuum advance unit may not be in the ideal position to get the ignition timing set correctly. The advance unit may hit the firewall or the intake runner. By moving the entire set of plug wires over one terminal or two positions on the top of the distributor, you are doing the same thing as if you pulled the distributor and reset the position correctly.

It is kind of like setting your clocks back for daylight savings time. The clock is still telling you the right time, it is just moved back one position.

You probably need to have the distributor rebuilt and have the advance curve set properly. Sometimes the vacuum advance canister goes bad and either doesn't work anymore or creates a vacuum leak. If the mechanical weights are sticking, you won't get advance at all. I have a guy out west do mine and the difference is amazing when you have a properly operating distributor. Lazy advance curves will make a car run crappy and slow.