Lifter Tick after rebuild

[D.PASSMORE]

Had my GEN1 350/SBC fully machined/rebuilt by a reputable engine shop.

In a nut shell, I did not stroke it, machined bottom end to just change pistons/rings to fit my desired specs. So bottom end is standard stroke. Had the blocked decked to ensure quench is where we wanted. Top end: AFR 64cc aluminum heads, Harland Sharpe 1.5 roller rockers with summit brand 5/16, 7.750 pushrods used with guides. Lunati Voodoo Hydraulic Flat Tappet Cam & Lifter Kit 10120701LK, Edelbrock intake manifold 2101(Spread) with a sweet Quadrajet. Running a Small DUI distributer setup, curved for a mild performance SBC, Taylor wires and Champion platinum 3025 plugs. Engine runs smooth with good power, AF is correct, 12 at idle, 13+- acceleration and 14.7 at cruise. Temp stays constantly around 160/170 degrees. Good oil pressure at cold start, runs at about 45psi (Hot) and it drops off to about 15-20 psi (Hot) at idle, 800 rpm. I just completed 1000 mile break-in, using Amsoil 30w break-in oil. Now, running Penn 10-30 motor oil with Napa Gold filter.

Issue: Ran the motor soft for the first 500 miles, never over 4k RPM. About 600 miles a stabbed it a little hard up to about 4,5K and back down rather quickly. Started hearing a lifter tick after that run on passenger side bank (2-8). Starting getting worse after another 50 miles. So I investigate, engine still warm, pull the valve cover and feel the rocker arms out, notice considerable play in number 6 intake rocker. Tighten it down about quarter turn to eliminate play (up and down), runs solid for another 50 miles or so, start to here ticking again. Next morning, investigate with engine cold, sure enough, 6 intake rocker lose again, tighten it down about quarter turn to eliminate play (up and down), and runs solid for another 50 miles or so, start to here ticking again. Opened valve cover again, this time I swapped rocker arms with known good one. Tick comes back, same valve/rocker. I’m starting to think CAM is wiped on that lobe, but no signs (glitter) in the oil. Oil is really clean, so I open top motor and replace lifter with a lubed up replacement Lunati lifter. Runs great for about 100 miles, ticking is starting to come back on same rocker/lifter set up. Couple things: Oil pumps through all lifters/pushrod with good flow. The replacement lifter seems to have less volume coming out. The ticking/tapping is noticeable at idle, but not all the time. Starting to get me really concerned…

Thoughts/Ideas: First, maybe a restricted oil passage to that lifter. Second take a good look at the CAM lobe tip through lifter socket/hole, maybe it is getting wiped. Third, remove all lifters/pushrod, laid out by socket/hole sequence, inspect them all. Fourth, check the valve spring to see if it broke. Fifth, with special air nozzle blow out all upper oil passages that lead to lifters. Six, replace all lifters with GM Delphi lifters, reassemble top end. Dial it back in, see what happens…

Any better ideas??