What Jerry is saying is that only 60 were produced and sold before the updates to the reliefs were made for the oversize valves. After reading this entire thread again I havn't seen anyone report valve clearance problems with the pistons that have the reliefs cut closer to the edge of the pistons. These appear to be easiy recongnized by the way that the reliefs are extended over and slightly off the surface of the pistons. In other words if the piston shows a dip on the outer edge of the exaust reliefs you are good to go. Those with the problems appear to have the pistons that have the straight/flat material still left on the outer (bore side) portion of the exaust reliefs. Riva has confirmed that 60 pistons were produced and sold with the smaller reliefs, this would suggest that 20 sets were sold and that 20 customers/engines were/may have been affected. I think we should start another thread only for logging proven and not suspected instances/customers affected. Keep all the remarks and comments totally in this thread and use the other for tracking the affected customers only. Information such as date of purchase, pics, information on the failure and etc. should be entered. Information such as RPMs, weather head or block has been decked, valve size, timing settings, valvetrain, and etc. should not be included as these variables are not in question at this point (thanks Duke). I will start the thread so we can see if we can find all 20 customers/engines.