Jim hit the nail on the head. The stock tank has baffles. If your hot rod tank does not I don't see a way to stop it. The tank in my '38 is baffled on three sides with the side of the tank making the fourth. There's 1/2" open at the top with only small drainage channels on the bottom.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.