Pushrod selection

Personally I wouldn't put the adjustable rockers on that combo. Yes you can 'adjust' them for more preload, but if the pushrods are already too short, you will have too much adjuster exposed beneath the rocker body and that can cause real problems. Then there's the possible (likely) geometry issues. Plus you'd be buying new pushrods anyway unless your new rockers already have cup adjusters? A lot of added hassle that may not even fix the issue. And checking pushrod length is FREE baby! Roll the engine until the lifter you're looking at is on the base circle/heel/back of the cam lobe. At that point the pushrod should be pressing the lifter cup away from it's retaining ring some=preload. If you have a minimum of .020" and IF you have regular hydraulic lifters, then the pushrod length is okay. You can safely preload them as much as .100" so uneven valve tip heights are inconsequential here unless they're WAY off. The plunger in the lifter will compensate within that range..so if the pushrods are preloading the lifters like they should, and there's no signs of a bad lifter/lifters, and all else is okay then the 'unknown' cam is likely the noisy kind PRH is talking about.