Answer:
see attached
Explanation:
You want a clock face with an angle of 240° between the hour and minute hands.
240°
There are 22 possible locations for the minute hand such that the long arc between the hour and minute hands is 240°. The two of these that do not involve fractions of a second are 4:00 and 8:00.
The next occurrence will be 21 minutes 49 1/11 seconds later. And the one after that will be 43 minutes 38 2/11 seconds later, or 1 hour 5 minutes and 27 3/11 seconds after the first occurrence of the pair.
Image
A clock face illustrating 8:00 is attached. You may need to scale it to your desired radius.
You can set your compass to 2" and draw the clock face circle. The points for 12 and 8 can be located by using the 10:00 position as the center of arcs with the same radius. Where those arcs intersect the original circle are the locations of 12 and 8.