Engine ground clearance

[alga]

Yesterday I got curious about how much can the engine stick out from below the bottom of the chassis. The engine mount boxes in the book are 68 mm high, sitting on top of the bottom rails, which makes their height 93 mm above the bottom of the chassis. I looked at my Pinto, which is still on its crossbar. It looks like the bottom of the rubber mounts is about level with the bottom of the block (which always coincides with the crank axis, right?), maybe some 5 mm higher (might be due to worn rubbers). I measured the height of a Type 9 transmission from the center of the input shaft to the bottom of the bell housing flange at 155 mm. So, if the sump is cut at about 150 mm from the bottom of the block, the engine would stick out some 6 cm below the chassis, is that right?

In other threads AshG mentioned that you need 100-110 mm to clear the speed bumps, and the roadster's ride height is 100-125 mm at the front, an inch higher at the back.

This does not add up to me. What am I getting wrong?