....During cranking over the the starter motor.

Is this normal to get a bit of heat or have a i got an earth problem somewhere? The wiring setup i have for the car has the battery earth cabled to the slam panel and the gearbox. The engine also has an earth from a bolt hole on the rear of the block to the chassis leg and the gearbox to the chassis leg. Do i need thicker cables or more cables.

Any help or advice appreciated as the last thing i want is an engine bay fire