What is "lead of the ignition"

Lead \Lead\, n.

1. The act of leading or conducting; guidance; direction; as, to take the lead; to be under the lead of another.

   At the time I speak of, and having a momentary lead, . . . I am sure I did my country important service.
   --Burke.

2. Precedence; advance position; also, the measure of precedence; as, the white horse had the lead; a lead of a boat's length, or of half a second.

3. (Cards & Dominoes) The act or right of playing first in a game or round; the card suit, or piece, so played; as, your partner has the lead.

4. An open way in an ice field.
   --Kane.

5. (Mining) A lode.

6. (Naut.) The course of a rope from end to end.

7. (Steam Engine) The width of port opening which is uncovered by the valve, for the admission or release of steam, at the instant when the piston is at end of its stroke.

   Note: When used alone it means outside lead, or lead for the admission of steam. Inside lead refers to the release or exhaust.

8. (Civil Engineering) the distance of haul, as from a cutting to an embankment.

9. (Horology) The action of a tooth, as a tooth of a wheel, in impelling another tooth or a pallet.
   --Saunier.

10. (Music.)

    1. The announcement by one voice part of a theme to be repeated by the other parts.

    2. A mark or a short passage in one voice part, as of a canon, serving as a cue for the entrance of others.

11. In an internal-combustion engine, the distance, measured in actual length of piston stroke or the corresponding angular displacement of the crank, of the piston from the end of the compression stroke when ignition takes place; -- called in full

    lead of the ignition. When ignition takes place during the working stroke the corresponding distance from the commencement of the stroke is called

    negative lead.

12. (Mach.) The excess above a right angle in the angle between two consecutive cranks, as of a compound engine, on the same shaft.

13. (Mach.) In spiral screw threads, worm wheels, or the like, the amount of advance of any point in the spiral for a complete turn.

14. (Elec.)

    1. The angle between the line joining the brushes of a continuous-current dynamo and the diameter symmetrical between the poles.

    2. The advance of the current phase in an alternating circuit beyond that of the electromotive force producing it.

15. (Theat.) A role for a leading man or leading woman; also, one who plays such a role.

16. The first story in a newspaper or broadcast news program.

17. an electrical conductor, typically as an insulated wire or cable, connecting an electrical device to another device or to a power source, such as a conductor conveying electricity from a dynamo.

18. (Baseball) the distance a runner on base advances from one base toward the next before the pitch; as, the long lead he usually takes tends to distract the pitchers.

    Lead angle (Steam Engine), the angle which the crank maker with the line of centers, in approaching it, at the instant when the valve opens to admit steam.

    Lead screw (Mach.), the main longitudinal screw of a lathe, which gives the feed motion to the carriage.