Engine - Cylinder Bore Size Location Information

SOURCE: Subaru Tech Tips

TITLE: Cylinder Bore Size Location Information

APPLIES TO: All F4 engines

SERVICE TIP:






The cylinder bore size is stamped on the cylinder block's front upper surface, behind the alternator, along the case half centerline. Please refer to the figure. Our pistons are designated either "A" or "B" and it is very possible to have two (2) different size pistons in the same block.

NOTE: It is extremely important to install an "A" piston where an "A" piston has been installed and a "B" piston where a "B" piston has been installed. The two sizes CANNOT be interchanged.