What causes or indirectly causes Valve train tapping? I have an 83' K-5 Blazer that I use for hardcore rock crawling and the 350 chevy motor is fairly new with only 20k miles. I chagne the oil with valvoline every 3 miles. These 3k miles are nast rough dirty miles... I try and maintain the motor as best i can but it has developed a heck of a tap. possible causes. I'm sorry if this is the wrong topic area but i thin maybe lubrication may be a factor.