If the springs are just a lil weak, the engine doesn't care at low rpms. But as the Rs rise they begin to bounce around and the lifters jump into action and take up the slack. Now the valves are not closing any more.And if it's intakes, the heavy valves, that are floating then exhaust can get up into the intake. But worse is the pistons begin to pump the freshly inducted mixture back into the intake where it mixes with the exhaust from other cylinders. And of course when ignition occurs it lights the fire and some of the now burning gasses get up into the intake through the non closing intakes.
The result of all this is a lotta popping in the intake, and the engine just flat quits revving.
But if it's the exhaust valves that are not sealing, then on the intake stroke, which immediately follows the exhaust stroke, now the falling piston sucks back some of the exhaust, as it is pulling in the intake charge. So now the engine suddenly goes lean and possibly the hot exhaust pre-ignites what's in there, and the popping goes out the exhaust, and again the engine just quits revving. This is the most-likely scenario.
Depending on how loose the springs are and how far the lifters have pumped up, and how well the lifters are doing their job; When the revs fall below this floaty business, then recovery time can be anywhere from several/many seconds to a few minutes. If you shut the engine off with pumped up lifters, it can take forever for the lifters to bleed, cuz only 4 of them are under pressure at any one crank position.
And yes with .135 lifter travel, on certain builds, the pumped up lifters can drive valves into the pistons, resulting in bent or broken valves, and trashed engines, or just very low cylinder pressures.
I always do an LD test whenever an engine quits revving, it's just the safest thing to do. If I suspect bent valves, I just back off the rocker gear and put any old amount of air into the chamber. The air pressure will normally push the piston to the bottom, and then start leaking out one of the valves. I don't need to know what percent is leaking cuz it will be obvious. With the piston at the bottom, and the valve gear off, I can tap the valves with a hammer/mallet and see if the valve pops back onto the seat. I know the sound they are supposed to make when the valve hits the seat and seals the chamber. If I don't hear it and the valve is hissing, there is no point in going any further, I just pull the heads.
I'm not saying this is OPs problem but checking is cheap compared to throwing parts at it and hoping for the best.
