I am rebuilding a pre 1972 4 bolt hp.61 nitro engine. I am wanting to run 10% nitro with it. What I am looking for is a chart or a Idea on what nitro content should be used at what compression. I am smart enough to know higher nitro changes timing and so does compression. What should the compression be for this engine if I turned the crank taking the reading at a moderate rpm of 200 rpms using a cordless drill. Thanks for all your help