If he calls the flop he's decided to look you up with a big ace or he's on a spade draw. I'm assuming that you don't have much of a hand and you're asking "should I fire another another round with cock?" Well you've got $48 left to work with and the pot is $40. If the turn is a spade and he checks I think I'd give up on the hand, he's commited with a good ace and he's CRing if he's got spades. If the turn is a non-spade I'd bet $12. No matter what the river is you have to bet it now, the pot is $64 and you have $36 left. If the river is a non-spade bet just eneugh to get the King high spade draw to fold, $15?? If the river is a spade and he checks, he's got an ace and he's scared of the flush, you have to push, "$36 to call TAG!!!"