I have noticed some Dirt Silver Crown cars are jacked up when the starter is engaged. Not all and I have yet to see this done on the pavement cars.

Why is done and only on some and none on pavement?

They sometimes jack up the rear of the dirt cars to get the front of the crankshaft lower and more parallel to the ground so the starter is more “square” to the car and the torque arm on the remote starter can be firmly on the ground. The dirt cars run a much higher ride height and get kinda of nose high/tail low with the full fuel load at the mile tracks.

The engine is higher in the dirt car and the starter shaft has to clear the front axle.