Was watching this video on youtube. Guy believes tick is caused by low oil pressure at low rpm. Tick is the lifter smacking against lobe as it slowly destroys itself and the lobe. Cure is said to upgrade to a high volume oil pump, as a hellcat oil pump or aftermarket. This increases your low rpm oil pressure. You probably have to still change out lifters and maybe cam, depending on how bad/ long its been ticking. Here is the video….
https://www.youtube.com/watch?v=jkNOXWGXADMPart number for hellcat pump is down in comments section. Hope this helps fixing some ticking hemis.
