The ornamental design for a timingbeltinstructionalmodel, as shown and described.
FIG. 1 is a left front perspective view of one embodiment of the timing belt instructional model;
FIG. 2 is a right front perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken line showing of a drive belt in FIGS. 1 through 8 is included for the purpose of illustrating environment and forms no part of the claimed design.