Hey guys. This should be simple but im second guessing myself so i thaught id ask u guys what u would do. I got a long block for my sons dakota with a 3.9 v6. Im fixin to put new motor together and i was wondering about tdc. Is tdc acheived when the intake valve just closes and the piston comes up or when the exhaust valve closes. I always thaught it was when the int valve just closes and u turn the motor a little bit more and the piston comes up to be tdc. I noticed the new motor is set when the exh valve just closes. thats 180 degree out from the way i thaught you did it. So which way is right?