Rob that is very loose were any of the nuts loose on the rocker arm
studs. I would look at the rocker arms for any defects like I was saying today.

I only got the one valve cover pulled on the starboard engine pulled today, but I suspect they will all be loose. Yes Dennis I am going to give them a good look before putting them back in. Okay so a couple more newbie stupid questions. Can you show me a quick diagram of which cylinder is which if I am sitting in the bench seat back words looking at the motor (looking at the harmonic balancer. Also I assume the exhaust valve's are the one's closest to the exhaust manifold's, and the intake valve's are closest to the intake manifold? Determining tdc on number one cylinder would be pulling the plug and bring the piston to the top of the compression stroke correct? And I take it the alan screw in the center of the larger nut is the set screw, so I would loosen the set screw, tighten the bigger nut, then tighten the alan screw to keep the nut there correct? Sorry for all the question's, just don't want to effff up my new motor's.

sitting looking at the front of the motor, the front cylinder on your right is the #1. Front end, port side of the engine. Port side is the #1,3,5,7, Starboard side is #2,4,6,8.

On the cylinders that you say you have 1/16 of play, if you can not move the rocker arm nut withyour fingers, they did not back off and you need to do some further reasearch as to why they are not set correctly. Intake valves are offset to the top, exhaust are the lower ones. Or just look at the valve in relation to the intake and exhaust ports.
I have had one rocker arm back off before but never several.

You can determine TDC by rotating the crank until the timing mark lines up with 0 on the timing tab, AND #1 cylinder valves are closed.

You can adjust the valves like obnoxus said, or you can do one cylinder at a time. Say you are on the #1 Cylinder. When the exhaust valve starts to open, adjust the intake. When the intake opens, and just starts to close, adjust the exhaust. Either way works. Basically what you want to do is adjust the lash while the lifter is on the heel or base of the cam(not on the lobe).

Also, when I adjust them, I do zero lash, then 1/2 turn, then i tighten the poly lock allen screw. THen, i hold the allen wrench, and box wrench, and turn them both about 1/8th of a turn. This helps snug them and keeps them from backing off.

At this point though, if all the rocker nuts are still tight (you should rotate the engine little by little and keep checking tightness), my guess here is gonna be you are losing your cam.

If they were adjusted wrong from the get go, they should have made noise all along. Not just start all of a sudden. I can see maybe one or two coming loose as a freak thing, but not several. I'd pull the oil filter off, and chisel it open. If theres lots of metal in there, you lost your cam. Highly unlikley if its a roller cam, but if its a flat tappet, very likely.

I agree with Mild Thunder. I would check your oil first. If you have a flat tappet cam it could be very likely you wiped off a lobe. I bought a boat that had a solid flat tappet cam in it and the guy told me the rockers need adjusting thats why the lifters were making so much noise. Which didn't seem unordinary since a solid cam needs rocker adjustments periodically. When we checked the rockers they were all loose and we just adjusted them. I ran 1 time on the water and it had no power. Tore the motor down and I had wiped off 9 lobes on the cam and put shavings all in the motor. Be safe and go ahead and check for metal instead of wiping out the motor.

OKay I am trying to absorb all of this information you guys are giving me. Thanks so much for all of the input thus far. OKay I need to call the engine builder and find out what cam is in the starboard motor. The port motor is making the marbely noise under the valve cover's like all the rocker's are loose. I know for a fact it has a crane hydralic roller cam and crane roller rocker's. It was making no noise until after our 1 hour trip, now it sounds like all the rocker's are loose. But from what you guys are saying it sounds very unlikely to take out a roller cam. The motor only had 30 mins on brand new everything, so are these valve springs just breaking in and need adjusting now? The second motor has 3-4 hours on it, and also has loose rocker's but I do not know 100% for sure yet what cam it has in it. I know it is a different cam because they where able to re use it when they rebuilt this engine. This engine has loose rocker's but also as the much louder tick/knock in it. Both motors where rebuilt at the same time but then the port motor dropped a valve which is why it has only 30 mins on it. When it blew it needed new cam at that time which is why I know it has the roller crane in it. I just can't imagine all these rockers being set wrong from a proffessional engine builder.

Maybe the engine builder isnt that proffesional. Sounds like a lot of issues for fresh motors.

Rocker adjustment should not need to be messed with after intial setup with hydraulic lifters. If everything is right, they should be adjusted, locked down, and be done.

I'd be pulling all the valve covers and taking a look and feel. I'd also be cutting the oil filters open and also taking a look. They're easy to remove, easy to cut open, and cheap to replace.

You said your motors are 1996 HP500's. They SHOULD have roller cams. I think they stopped using flat tappets in that motor in 94-95?

Keep in mind the rockers will all have a little side to side wiggle even when adjusted properly and the valve is closed.

Probably a dumb question, but these are "new" motors. What kind of oil pressure were you seeing? Hydraulic lifters work off oil pressure, and reversed oil lines, broken pump pickup tube, and several other things can cause problems.

OKay I think I got some good news. I called the engine builder today and he was very helpful. Both of these engine's where set up the same, with crane roller cams and SOLID roller lifter's, with crane roller rocker's. They are adjusted to 10 thousands lash and am being told the marbely sound under the valve covers (especially aluminum one's) is very normal with solid roller lifter's. So that explains the one motor, now I just need to find that tick/knock in the other one. Does this new info line up with what the engine builder is telling me? How often should the solid lifter setup be checked and or adjusted?