tabetha, i don't believe the problem to be crud i believe it to be swarf from the machining on the head when i had it skimmed, ported and polished when i rebuilt the engine. the tappets are new ina items which i fitted a couple if hundred miles after rebuild as the tapping only started after i rebuilt it.

would it be a idea to take the bungs out then with the cams and tappets removed blow compressed air through the little feed holes where the tappets sit?