We've been through this chain stretch thing several times here and in the techs only section. No one has ever come up with any documentation stating maximum degree of cam retard before chain replacement on the V8s. We've established a set of parameters by consensus. Pull both valve covers and rotate the engine until the crank is on zero. The mark on the right bank cam should be pretty close. That is the one on the passenger side. If the left bank or driver's side is late, rotate the crank with a 27mm on the pulley until the marks line up. If it is over 8* late a new chain is in order. If you continue driving with a streched chain, the whipping chain will eventually snap the inside rail on the left bank. The piece of rail will wedge in the teeth of the cam, stopping the cam, and causing the pistons to bend the valves on the left bank only.

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