I have a "67" 273 in my "65" Dart with approximately 8k miles on it. I bought the engine used with paperwork on the rebuild. Prior to installation I removed the intake and installed a flow through hi rise. While I had the intake off I decided I would change out the lifters (hydraulic) with new. I also had to change out the oil pan and at that time I also replaced the oil pump just for good measure. I placed the engine on a run engine stand and tuned before installing, it ran well. Installed the engine and put approximately 100 miles on it with no problems. I then developed a loud lifter noise on #4. I figured that the lifter had gone bad on me. I pulled that lifter out and replaced with another new one. Same result, noisey. The only thing I can figure is the oil galley is blocked somehow and that lifter isn't getting oil. What are your guys thoughts of an engine flush? Or any other suggestions. Thanks in advance for your input.