@centralcoaster33 I fed some rope into the cylinder to stop the crank from turning. The engine got a rattle and went down on power, and I believe it is the chain tensioner and guide. I bought the replacement kit and am just replacing everything I can. the chain is a wear item. I did check the valve lifter clearances and believe that is ruled out. the car is a high mileage 2005 car with 170+ k miles on it. I am finding the engine to be fascinating. have had continental airplane engines apart, and an mgb engine apart too, but this one is incredible. It is a lot more complex.