Pull nr one spark plug. Carefully with a long thin clean roundbar or a screwdriver,feel the piston.Turn the engine by hand.Before you try with the screwdriver you should see the piston through the plug hole.Turn the engine and see the piston in the upward position.When close to the top.try to see the timeing marks,if so line them up.Then use the screwdriver and keep you one hand on it and rock the engine forward and back with your other hand.Try to make the piston stay still between rock's.Then look at the timeing marks.They should line up,if not.The mark can be off by 2 or 3 mm.That will not make a diffirance.If way off, your mark are out,or the crank pully moved.In the patrol's case the rubber damper on the pully can move,and that is were the timeing mark sit's.Most mackies make that mistake to beleave the marks.So it is always good to test the mark.
The timeing I quote are for most petrol engin's,at least the one's you can tune.
Go with the timeing I said.Please listen for pinking.(timeing to fast.)
A little tip for big petrol engine's like a 4.2.Set your timeing and after that rev the engine with all vacuum hose connected @ 3000 rpm or a little higer.Watch the motor,if it are still,your timeing are spot on.If the motor are ,if I can call it, vibrate-running with a shake,the timeing are to fast.
Cheers
