Engine Mechanical problem
1987 Nissan Truck 4 cyl Two Wheel Drive Automatic 225000 miles
I have a Z24i, 4cylinder, throttle body, engine. I am rebuilding the engine. I am trying to verify camshaft timing marks. The book says, prior to dis-assembly, to make a mark on the chain & cam sprocket with the engine on #1cylinder TDC. I do not trust that the previous owners timed the camshaft correctly. They may be off one tooth. I rotated the engine several times by hand, and I noticed that at #1 cylinder TDC, the exhaust valve has just finished traveling upward, and that the intake valve is just starting to move downward. Also, I see a dot indentation on the cam sprocket, approximately in the 10 oclock postion, (facing the front of the engine), that aligns with the bolts that secure the intake side of the rocker arm shafts. Is that dot and the rocker arm bolt-line, the final authority to ensure camshaft timing?