I had that problem with a set of Crane hyd. roller lifters years ago when I did my 340 stroker. Problem was solved by using the Doug Herbert solid roller lifters. I believe these are also sold by Howard's as well(exact same part). I've had these in for around 11 years now and 8,000 miles street/strip with no trouble yet-knock on wood lol. Probably other ways to solve this issue now. FYI-these lifters can be removed with aluminum heads still bolted to the engine..