RhinoSS

I do understand what you're saying, however it seems the pushrod acts too long if anything. If it were wear related I believe I wouldn't have enough preload at 22 ft/lbs. I've seen a significant number of Gen III cam swaps without a lifter change with no ill effects. I'm not saying it's the correct thing to do, just simply that it seems pretty common practice with these roller lifters. If it were a flat tappet I wouldn't even have considered doing so.

If I were to pull the heads, a lifter replacement is a no brainer. If I can't get this setup to quiet down, it will simply speed up the process of a head/cam install. With that said I'd like to delay the process as much as possible at this point. I have a few projects that are way more fun looking to occupy my time

hirdlej

iTrader: (31)

If the pushrods were too long and bottoming out the plunger, the engine would misfire and run like crap from the valves being hung open. How long have you driven the motor since putting it together. I've had stubborn hydraulic lifters that wouldn't pump up for at least 20-30 minutes of HOT DRIVING (notice I didn't say idling). If it idles smooth but makes lifter noise go for a spirited drive for a good half hour. Sounds like you have a few that have a poor prime. You need to work the air out of the lifter galleys. If that doesn't fix it, get a pushrod length checker, and open it up to about a 7.550 length. Put the pushrod on each lifter with the lifter on the base circle of the cam. Tighten the rocker down using your pushrod length checker. Obviously the pushrod is too long but what we're doing here is backflushing the lifter by bottoming it out completely and pushing all the oil out of it. You should tighten the rocker bolt to just the point where the valve is hanging open. Back off and reinstall the stock pushrod. Do this for all 16 lifters and try again. There might just be a hunk of **** that worked its way into the lifter plunger assembly not allowing it to catch its prime. Then go for another 30 minute drive. Just remember, lifters never go bad. They just either get dirty or the wheel wears out on the bottom.

RhinoSS

Great info. Thanks. When tuning the truck I did take it on a few pretty long sessions. I do feel pretty confident that it's a lash/ lifter pump issue. Since I did find a bad cam bearing, I had wondered if some junk could have gotten caught up in it but didn't really know what to do to check. I've been meaning to get a pushrod checker for another engine build. I'm looking into one right now.
I've been driving it for a few weeks hoping that it was air in a lifter or something similar, but that seems less likely at the moment. Now I'm working the list with the least intrusive first.
It's also good to hear someone say that lifters don't go bad. I realize that's a general statement, but I had heard people mention of screwing them up with too much preload.

What are your thoughts on reassembly? Should I just torque to 22 ft/lbs like the GM manual states, or aim for a specific preload amount?

Gadgetized

iTrader: (9)

Always torque it down to 22ft lbs. You do not measure preload by not tightening it down properly. Preload is measured by an adjustable rocker or a different length pushrod. How many turns do you get before you hit 22ft lbs? Were the heads milled or anything. On another note, how did the bearing go bad? Were there warn parts that were used again? Are they all clicking, or just a few? What is you oil pressure?

AKlowriderZ71

iTrader: (22)

This. If you tried to "adjust" your valvetrain by 1.5 turns past zero lash, instead of torquing down the rocker arms to 22 ft lbs, then you have assembled it incorrectly. If that's how you did it, it should be making a hell of a racket.

I hope you get it fixed soon. Good luck to you.

RhinoSS

I was checking preload via dial indicator at the pushrod end of the rocker arm. The reason for the measurement was the noise I'm experiencing, thinking the valvetrain wasn't adjusted properly. My main concern was people saying that incorrect pushrod length or preload was causing similar noise. I didn't know if I introduced any issues with this different cam. Having pulled one from both engines I feel pretty confident that they're the same. I also did have a bit of a misunderstanding on exactly what was being done. It does make sense that this is only done on mock up.

I'll check again this evening, as I'm not certain how many turns it was to 22 ft/lbs. I want to say it was between 1 1/2 to 1 3/4 turns... but that's only a guess.
Heads are bone stock and were never lifted. I replaced all bearings while the motor was out, on the stand.
Quick history of the motor: Purchased locally off craigslist as a good motor. Was said to have less than 100k miles. Compression tests showed all cylinders pretty equal, bores looked good, with still seeing some crosshatching on the bores. The guy I bought it from got it for a project that never happened. More info here

I don't know the story behind the bad bearing, but it's the #2 that seems like is a common issue on these motors. The old oil pump looked good, but I never ran it to find out. All I did to the motor was a new lower gasket set, full bearing set, oil pump, timing set, and this other cam. Oil pressure is 45 at hot idle, 65 at around 3.5k.
Rod and Crank clearances were plastigauged and were in spec. In my opinion, I think it's 1, 2 at the most, lifters that are continuing to tick.

When I initially assembled everything I went by the book and did 22 ft/lbs. It was only when I had the valve train noise that I began searching into the issue and really worried about the preload. I had an incorrect understanding on when the measurements were being taken and exactly why. I think I've got it down now.

I do appreciate everyone's input. That's what makes these forums great.

Shogo

Were you able to adjust them properly