My flat tappet hydraulic cam is loud on my BMRE built 512. I had Chuck and Pete listen to it last fall and they said it was normal. Chuck said the aggressive ramps on the new hydraulic cam profiles make them loud. I have between one and one and a half turns of preload on it and it is still loud. I think the fabricated aluminum valve covers also amplify the noise. I have a little over 1000 miles on the engine. I have checked the preload several times and nothing is loose. The car runs great, so I’m not too concerned about it. But yes the tapping is annoying.