Locating dimple on timing gear

[100IH]

Have seen compression tester hose with a whistle in place of pressure gauge, You know how to whistle don't you. Handy if it takes 2 hands to turn the crank. Also, If the side cover happens to be off, the #1 lifters will be equally down - both valves closed AND #4 lifters will be equally up - both valves open part way. that is where compression ends and power starts TDC will be within 2-3 deg. one way or another. Don't use a dog whistle, you won't hear it.