No luck Adjusting Rockers
what procedure did you follow when adjusting them?
some hit the valve cover baffles with thin gaskets,but
that is usually quite loud.
He told you! He went "one full turn down"
To the OP:
Lemmie preface this by saying this is NOT personal so please don't take it as such. That is my disclaimer and I mean it.
You never ever EVER EVER EVER "just go X number of turns down". EVER. I don't care who told you to. Where you've read it. DON'T do it.
When you make hydraulic valve adjustments, you are adjusting lifter preload. Preload is the amount that the pushrod pushes the plunger into the lifter body when the cam is on the base circle of the particular lobe of the rocker that's being adjusted.
Here's where my disclaimer comes in. See that last paragraph up there ^^^^^? If you don't understand that, you have no business adjusting rockers. I'm not trying to be an ***, that's just the way it is. If I didn't piss you off, keep reading.
Lifter preload is "said" to be between .020"- .080". "One full turn" could possibly bottom the lifter plunger in some cases, depending on the thread pitch of the adjusters. Usually the cheaper brand rockers have very coarse adjusters that can bottom the lifter plunger really quickly.
So, when you make your adjustment, NEVER make it by counting the adjuster turns. GHEY!
Make your adjustment by watching the pushrod being depressed into the lifter plunger. Here's what you can do. With the cam on the base circle, tighten the adjuster to ZERO lash. That's the point where you have no more "up and down" slop between the rocker, pushrod and lifter WITHOUT depressing the lifter plunger any. Take a machinist's rule and lay it flat on the valve cover rail against the pushrod and mark the pushrod. Then adjust the adjuster on the rocker until your mark is about .030" DOWN toward the lifter from where it was. You just set lifter preload correctly for that one lifter. Repeat 15 more times.
Now.....this is all correct IF you are SURE you have hydraulic lifters. My guess is what's happened is, they have all been tightened down too far from what it sounds like. No telling what maladies that has caused. Good luck.