Took the boat to the launch yesterday to set timing and for first run after engine assembly. Right from the get go I can hear a knocking sound coming from the passenger side bank. Didn't sound like a rod knock, the frequency seemed too slow. I laid my head down on the valve cover and verrified the noise was definitely originating from the passenger side. Driver side bank was nice and quiet. After setting timing and idle we took it for a test spin. I can definitely feel a miss or surge upon acceleration. Oil pressure is around 25 psi at idle and at 40psi at higher rpms. Back to the dock, still knocking. Shut it off, check oil, looks fine. Tighten exhaust manifold bolts, fire it back up, still knocking. Then the knocking starts coming and going. It would knock continuously and then stop for 15 seconds and then start knocking again. WTF!?
To give you the background story, I acquired a gen 5 454 with 40 hrs of run time. The boat was stored in a building over winter and the building caught fire. The plan was to put it in my boat until I discovered the block was cracked due to improper winterization. I wound up buying a brand new GM performance 454 block from summit racing and swapping over all internals (crank, pistons, rods, cam, lifters, push rods, rockers, and timing set). I used new bearings on crank both main and rod in addition to new cam bearings. I used plastigauge to check oil clearances on all journals which were a little on the tight side. I was told by the techs at Mahle that this was normal with the type of bearings I was using. I checked end gap and side clearance for each ring which all fell within spec. I should mention that the new block is a gen 6 but from my understanding, not much difference exists between the gen 5 and gen 6 blocks. I should also mention the cam is a hydraulic flat tappet. The cam and lifters were not replaced.
Got home from the launch and pulled the passenger side valve cover off. I was hoping to find a collapsed lifter. All rocker arms had the normal amount of play. These are the non-adjustable type. All the lifters were pumped up and would not compress when applying pressure.
Today I pulled the distributor and put the oil priming tool in. The tool I use was made from an old distributor with the drive shaved down. I was turning it with a power drill. Oil pressure was around 40 psi. It seemed like the driver side bank was getting more volume than the passenger side. All rockers on the driver side had a nice steady drip. The first 3 rockers on the passenger side were getting oil but did not have the same steady drip as all the others.
I read something about the oil galleies that feed the lifters having threaded plugs at the front of the block where they terminate next to the cam bore. Some were saying to drill holes in the plugs to allow trapped air to escape. Not having the holes can cause lifter noise on start up. I don't remember if the plugs that I removed from the old block had holes in them. I know I installed some new plugs in some locations but do not remember where and do not remember if the ones that came out of the old block went back in the same places.
I don't know where to go from here. Can a lifter intermittently make noise? Can a liftet pump up and be stiff but fail under the force applied by the cam lobe?
Any help will be appreciated.