Dont be surprised if you find a lifter and cam lobe has failed, especially if you use Synthetic oil in the engine.
Flat tappet cams and lifters need an oil that has ZDDP additive in the oil...(zinc) to protect the flat running surfaces.
You can use an additive or buy an oil with zinc included in the mix. You need between 1200 to 2400 ppm of zinc to protect fully.
