I just finished doing a full timing chain job on my 4.0L. It was my first time doing so - I used the OTC 6488. I believe I got everything done correctly. But when I turn the crank manually, it takes two full revolutions for the camshafts to be in the correct TDC position (horizontal keyway parallel with top of valve cover rails). Is this correct? I guess I assumed it was a 1:1 ratio of crankshaft revolutions to camshaft revolutions. Is it not? Or did I screw something up?

 

I should clarify. I’m starting from TDC at crank, and with the timing marks on cams parallel w/ valve cover rails and the horizontal slot sitting below the center axis - then rotating crank 360 degrees - the timing marks on cams are still parallel with the valve cover rails BUT the slots are now above center axis.

 

4-stroke engine requires the crank to go around 2 full turns, 720deg, for the cams to make 1 full turn, 360deg
Jack shaft gear should have twice as many teeth as the crank shaft gear

 

Thank you! I couldn’t make mathematical sense out of it. It seemed impossible the crank could keep up with the cams at a 1:1 ratio - just based on size of gears. But I was also interpreting the consensus to mean anytime the crank was at TDC, that the cam timing marks should be positioned correctly.

Really appreciate the help.