It is a g52b for a 78-82 2.0 astron motor - it will raise the compression with a smaller combustion chamber but may not fit on 2.6 motors after 1984 due to changes in the configuration of the ports between block and head. The post 83-89 g63b 2.0 or 89 up 4g64 2.4 heads will not fit the 2.6 as they are a different engine series. There are several sellers with non jet valve heads out there that a machine shop can port for you, or you can port them yourself if you are up to it.