George Jets said Your '87 318 roller Truck engine came with the factory 9.2:1 cr flat top pistons. Good to use those, and they are already balanced with the assembly. View attachment 1716471161 Aftermarket pistons have a lower compression height coming in closer to 8:1 cr like your '73 318 engine came with. ☆☆☆☆☆ Click to expand...