How do I tell for sure if I dropped a lifter

[usraptor]

440 with 512 stroker, Lunati 704 hydraulic cam with Lunati lifters, PRW rocker arms.  Engine break in has been done and engine has been fired and run several times, no more than half throttle, but car has not been driven so engine has less than 1 hour run time.  Last time we fired the engine it was running fine and all of a sudden we got a load valve tappet noise.  One second no noise and the next second noise.  Turned engine off and pulled the valve covers to find that cylinder No. 3 push rods were extremely loose and in fact had hit the edges of the adjustment cup.  Re adjusted all the valves (all on the loose side but nothing drastic like NO. 3).  All the lifter adjustment screws stick out of the top of the jam nut approx 1/4" and all are within 1/32" of each other, except No. 3.  To get No 3 adjusted the adjustments had to be turned down to the point the top of adjustment screw is virtually even with the top of the jam nut.  I turned the engine over several times (but didn't start it) and the no 3 rockers went up and down like normal so I assume the cam is okay.   So obviously I'm going to have to pull the intake, rocker arms and push rods.  But since the lifters are spring loaded I assume once the pressure from the rocker arm and push rod is released the lifter piston will resume it's normal height.  So how do I know for sure the lifter is bad?  Secondly, why would both lifters on the same cylinder go bad at the same time and why on such a fresh engine  Obviously when I pull the lifters I'll check the cam.  But I'm keeping my fingers crossed it's the lifters and need to know how to tell if they are defective.  I know in the past Chryco has said he has had lifters fail and in fact will only run one particular brand.  (Can't remember what he recommended right now). Hopefully he'll chime in.    ?   

[Roadman]

           I hate to say it, but sounds like cam lobes. Lifters rarely go bad.            

[usraptor]

If it's the cam, why does the rocker arms still go up and down when I rotate the engine?

[Roadman]

If it's the cam, why does the rocker arms still go up and down when I rotate the engine?

           Well because there is still some lobe on the cam. First thing I would do is drain the oil and run a magnet thru it. See if you have and metal in it. Pull the filter, cut it open and check for metal.  Hope I'm wrong man.   

[usraptor]

Me too.  Anybody else?

[Cuda Cody]

Did you use a break-in oil with a lot of zinc?

[Roadman]

   Hey @Chryco Psycho  your thoughts. 

[RUNCHARGER]

What you are looking for is the lobe a bit flat at that position and the bottom of that lifter mushroomed out. If you can shine a light in there to check that you can tell. Other way to tell is measure how far that valve moves (measure how much the spring compresses) in comparison to the other ones. You can do it with a dial indicator or even a caliper. Another easy way to check is pull off the oil filter and cut it open to see how many metal particles you have in it.

[usraptor]

Did you use a break-in oil with a lot of zinc?

Cody, yes, tons and I added zinc additive on top of it.   Currently running Hemings MO with more zinc.

[cudabob496]

lifters burp on high revs, and you will have no oil pressure

[usraptor]

lifters burp on high revs, and you will have no oil pressure

Haven't run the engine past 3K RPMs.   When the tappet noise started I failed to look at the oil pressure gauge.  When I took the valve covers off there was plenty of oil on top of the head.  If only two lifters failed would that cause no oil pressure? 

[anlauto]

If you only have 15 left, look under the bench....those suckers tend to roll

[Chryco Psycho]

without a lifter oil pressure will drop to zero, pushrod should disappear also !
If the adjustment is that far out I bet the cam wiped , lost a lobe , us a magnet & you should be able to pull the lifter without removing the intake etc & you will know immediatly if a lobe is gone as the lifter face will be damaged & the lobe rounded off too .
Johnson lifters are what I use but they are resold under different brand names .
I feel you pain , you can do everything right & still lose

[1 Wild R/T]

Drain the oil, take the oil out in the sun & see if it glitters like a metallic paint job...

[jimynick]

As mentioned, if you've reset the valves, simply use a dial indicator with a magnetic base and measure the actual movement of the rocker arm where the push rod goes into it. That'll give you the lobe lift and if that one's .250" less than the others- there you are. After that, it's change the cam and flush the engine time. Hopefully (but not confidently) it'll be something else. Bummer.