On the 1967 318, we have a sticky lifter. We hear it at idle, but it goes away when we rev it and the oil pressure goes up. It then returns at ilde. The engine did sit out of the car and didn't run for at least a year . We tried an oil additive, but that didn't work too well. Also, it is only there 70% of the time. There have been times when it is started up and makes no noise. Also , can running a sticky lifter for too long break/ harm anything? What should we do to fix the lifter? Thanks