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Originally Posted by Decipha
lets say i removed the timing chain cover on my 4.6 removed the timing chain and spun the cam shaft a full rotation, then lined up the crank shaft and cam shaft and put the timing chain back on... whats the chances of the engine starting up? do you think i bent a valve by turning the cam shaft even though the engine wasn't running?
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Can't be done, not directly the way you put it --
1) There's not one Timing Chain, there's two -- one to each Overhead Cam.
2) There's not one Camshaft, there's two -- you can't spin "the" Camshaft, it's one or the other.
Let's say you removed one Timing Chain, presumably the passenger side since it comes off first, then you tried to "spin" the 1-2-3-4 Camshaft.
There's a hit & miss chance in theory, that the Camshaft 'could' turn 360 degrees back to where it was to begin with however, in actual practice that would proove quite difficult, not impossible but difficult. Remember you'd be fighting the resistance of all the Valve Springs at this point.
I say hit & miss because you also may have some Pistons parked in the operating path of the Valves.. Is a Valve, combined with the strength of your hand tools, strong enough to move a Piston out of it's path, and not bend the Valve stem.. hmmm. In rare cases the Valve hitting a Piston in this scanerio, might cause the Piston to turn the Crankshaft (and all the other pistons) and not bend the Valve stem.... I wouldn't try it though, not on something I intend to use. The slightest bend to a Valve stem isn't detectable by the naked eye and will cause the Valve to not seat properly. Improper seated Valves = Zero compression, or quick leak-down.
What's the chances of the engine starting after that? Well, there's a chance some Valve stems were bent, and maybe not. As for starting up, you would still have at least six unscaved cylinders IF nothing is left out of this post, I thiink the engine would start on six good Cyls.
Here's your engine layout