Mercruiser Setting Timing on 3.0L

[kd4pbs]

If the head cracked - due to improper tightening sequence even when there is a gasket that is compressing - then it would have surely failed while in service. A huge thick hunk of cast iron is much more resilient than you might think. The gasket will have already been compressed, so there will be no issue. But if you feel more comfortable following a sequence, then there's no reason not to do so.
As far as the lifter preload, I'm referring to the valve lash (zero lash plus the 1/2 turn or so preload). What you do when setting the lash is actually put a preload on the lifters which pushes the adjusting piston down into the lifter against spring pressure. It is imperative that this is done on the base circle of the camshaft where the lobes are not lifting the lifters. The best way to ensure this is that the cylinder be at or around top dead center on the compression/power stroke. Looking at where the rotor is pointing and working on only that cylinder is a great wat to ensure this.
I have a friend that built a very expensive hopped up 350 for his '68 Camaro back in the 80s. For some reason, he got it in his head that the cold valve lash (it was a solid flat-tappet cam) be set with the piston at TDC between the intake and exhaust strokes. Of course, this is 180º wrong and both intake and exhaust valves are open at this point, known as overlap. I was there when he first started it, and it sounded like a coffee can full of marbles in a paint shaker. I warned him immediately to adjust the valves the proper way, but he insisted on adjusting them by ear while the engine was running and the valve covers off. He never got it right due to constantly chasing the lash down as the cam was being wiped on every revolution. Poor guy. After he realized something was wrong and started tearing it down, it looked like someone sprinkled silver glitter in the oil. At least he realized the error of his ways after new bearings, rings, oil pump, cam, and lifters.

 

[ESGWheel]

KD,
Holy Cow Batman! Expensive lesson.

Dan,
More on what KD is talking about with respect to valve lash (aka valve adjustment). Your lifters that sit on top of the cam that the pushrod seats into are hydraulic (vs solid). Literally a little cylinder with a piston inside with a spring underneath and filled with oil. The preload pushes down that piston just a little bit and as the engine runs it compresses that piston and pushes oil out, up the pushrod, and oils the rocker. It’s really a marvel of engineering. Lots of vids out there and I encourage you to watch a few as part of developing your expertise. For the How To, idea is to mark the distributor cap plug wire sockets with which cylinder it corresponds to. See AD’s post no. 11. Do not have any wires in the cap. As you rotate the engine, keep pulling off the cap and eyeball to see if the rotor is pointing to one of the plug wire sockets. Look directly overhead when you pull off the cap, ie straight down along the same line that the dist. shaft would make if it was extended. That is the cylinder’s valves you can adjust. So initially takes a little bit of turn engine, pull cap and look, turn engine more, look again and until have it pointed almost dead on one of the cap plug wire sockets. Once done, rotate engine 180 degrees and will be at the next cylinder > pull cap to check and do that cylinder’s valves.

Looking forward to the pics once apart....