Timing problems - hesitation
Make sure the water pump belt is very tight, make sure the ign. sw. is OFF.
Grab two opposing blades of the fan and rock the engine back and forth. The
freeplay you feel is the slack in the timing chain. If you want to, you can
mark the balancer at the timing mark and check the amount of slack. More
than 15 degrees and the chain is in need of replacing.
I have seen engines running with as much as 30 degrees slack
Jerry Forrester  Aug 2004