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I have a rebuilt engine I bought a few years ago that said it had a lifter tick. I installed a new melling MTA-1 cam when I installed it in my jeep and after break-in it still ticked. fast forward a few years and a few thousand miles I am fighting what I think is a vacuum leak in the intake manifold and want to address the tick. I pulled all the lifters and they look fine. the rockers appear looser on the valve than I would expect I can rattle them a bit when the cylinder Is on the compression stroke.
I pulled the valve cover on a spare motor I have and the rockers have more preload on the valves than this engine, could I need longer pushrods? The engine is stock other than the cam and the push rods appear to be stock and the same length as the push rods in my other motor.

What lifters did you go with? It sounds like maybe their seat height is lower, which would require a longer pushrod. That or for some reason they aren't pumping up.

I bought the kit from melling it came with lifters.