i pulled my SBC 350 apart to put new gaskets in it and im just wondering if i should be cleaning the piston tops and heads before i put it back togther. the motor has 10,000km(6,000miles). heads were new but pistons were reused when it was rebuilt. i attached a couple pictures, they seem to have a fair amount of carbon on them for a motor that wasnt lightly used? is my carb running to rich?