An easy way of checking if your timing is right, is to take off your rocker cover and turn the cam shaft until the cam lobes on no.1 cylinder are pointing straight up this means that the valves for no.1 are completely closed,now remove no. 1 spark plug put a long screw driver into the plug hole resting on the crown of the piston, now rotate the crank shaft and watch the screw driver rise to its highest point before its start to drop again, this called top dead centre ,now check your timing marks to see if they are alright or just refit belt using this method and u will be a 100%