I need help with a problem on a 454 I am building. I have a 1979 454 with a high lift cam and needle bearing roller tip rockers. The problem is in the adjustment. When I set the adjustment at 1/2 turn past zero lash I end up with the valve being held open. I have OE GM hydraulic lifters new 3/8' push rods with guide plates. The rockers are aluminum needle bearing with roller tips. If I set the adjustment to Zero lash I have compression but it does not seem right.  Any suggestions?  

when you are setting lash is the lifter on the heal of the lobe?  what type of lock nut or adjusters do you have? (poly lock)?  1/2 turn past 0 lash is a bit to tight to me....CHP just did an article on valve adjusting, you may be able to search on this site and read up on adjusting lash...finding 0 lash is the key....are you twisting the push rod to feel tension or are you lifting the push rod up and down to feel 0 lash?  CHP recommends  twisting the push rod and when you feel a slight drag, that is zero lash.  I guy that helps me build my race engines told me years ago, "no more than a 1/2 turn"  for poly locks they say 1/6 of a turn then lock the center allen then tighten again no more than 1/6 of a turn.  hope this helps...  

A half a turn of lash is about right, I set the hydraulic roller in my 350 to that, runs great. Sounds like when you're setting the lash the lifter isn't on the base circle of the came lobe. Rule of thumb, set lash/preload when the intake is just starting to open, and the exhaust is just closed.

Another thing to check, are your pushrods too long?  

Thank you for the responses.  I have Crane energizer aluminum roller rockers P/N 13744-16 with poly lock.  I use the rotating the push rod method of finding zero lash.  How does one determine correct push rod height?  As this was an engine that has had previous rebuild, I assume the heads were surfaced before. Along with the time I just had the valve job done.  

those are new lifters right.... not filled or pumped up by you in a can of oil with a push rod....

last few times i have hurd about valves being held open during valve ajustments teh ajusters were bottoming out the lifter plunger agenst the internal spring thinking that is 0 lash....

0 lash is when the slack is gone out of the but the lifter plunger is not depressed at all... with fresh lifters not filled with oil you should be able to get .080" or  feeler gauge under the rocker arm tip to the valve stem when you depress the lifter by rolling the rocker with your hand ....

on motors with non ajustable valve train.. this is how you tell if you need a longer or shorter pushrod when you are building a fresh motor....

i also like to prime my motors with either a speed handle or drill motor to fill the lifters at least partally before starting the motor so the lifters dont have to bounce off the internal spring while waiting for the oil to come up and fill them....


i also line up the reluctor and pick up coil teeth with the balancer at the base timing mark...   this allows the engine to start and run for cam break in without needing to time the motor... it is usually within a few degrees of being right on... try it   amaze friends...  turn the key on a fresh motor and it starts and runs on the first turn of the key without touching anything....  

Yes the lifters are new OE GM HD lifters. The engine was primed and the master oil pres gauge had 40psi.   Even after the engine has sat for a week on the stand the problem is still with me.  One would think the oil would of bled back out of the lifters. I will check to see how much clearance I can get by depressing the rocker after zero lash.  
Your suggestion on presetting distributor and timing is a good one I have used it for many years setting the distributor to line up on the factory punch mark on the intake and base of dist shaft housing.  I end up with turnkey running engine every time.