tapping noise valve area

[frankyjoet]

Have 73 GMC 350V 3/4 TON 5.7L rv cam roller rockers. this engine is not broken in. has 50w oil. tried adjusting valves get a tweety sound with the tapping noise. i am trying to do the adjusting with the valve cover off at low idle on the pass side. recently replaced all plugs and header gaskets. the truck sits in the garage and gets started daily. prepping for paint. need help

[mud.man.rj]

Not sure on noise but found with all the roller rockers I have used that they actually make more valve train noise that a stock rocker arm, is there 1 certain rocker arm or all of them. If you adjust with running at idle, loosen till it clicks then take click out and tighten 5/8 of a turn past that and should all be good if not maybe wiped a lobe out if it is really loud.

[bnoon]

Why in the world are you using 50w oil on a new engine??? You should be using thinner oil if anything, plus a break in oil (or additive) with high zinc content. The heavy weight oil alone could cause issues because the oil can't get to where it needs to go. New or recently rebuilt engines can have very tight tolerances which restrict oil delivery. You're adding to that restriction by using a heavy thick oil.

For any hydraulic lifter, adjust to zero lash (no up and down wiggle movement), then add half to three quarters of a turn. I've never needed to do a hot/cold adjustment ever on hydraulic lifters. I have heard of (but never experienced) bad hydraulic lifters out of the box. If that's suspected, check that the spring lifts back up after pressing it down with the pushrod firmly. Should be a 16th to an 1/8th inch of travel max. If there's no spring return to the "up" position = bad lifter. This travel is what takes up the slack caused by expansion/contraction during running/sitting cycles. It's also what gets rid of complicated adjustment procedures of mechanical lifter setups that you don't need to do here. Now, if you have mechanical lifters on an RV cam, then we have other things to talk about.

[naphtali5725]

if it's a hydraulic flat tappet cam... if you don't follow proper cam break in procedures with a good break in oil, or a high zinc oil, preferably 10-30/10-40 it will wipe a cam lobe in no time...

how many rockers are making noise?

check this
http://www.cranecams.com/uploads/breakin/548e.pdf

[Corts60]

I agree with bnoon. Change that oil back to 10-30 with a zinc additive. Also, as far as I'm concerned, if the roller rockers are not made by Crower, they are garbage.

[frankyjoet]

bnoon and others, problem resolved. found tdc cycl 6 adjusted rocker no noise. thanks for the help.

[bnoon]

Had the same problem on Mr. Green Jeans a couple of times. Had a bad set screw on one of my poly locks. Good luck with it from here.