For the ultimate in engine performance, these pistons, installed in a 1275cc block, will blow your doors off! You can't beat cubic inches for performance, and the A-Series block can be bored far bigger than the factory ever imagined. The stock bore is 70.6mm, the 1380 bore is 73.5mm. This is .120" oversize and still leaves room in the block to go to 74mm (1400cc), but only if you offset bore prior to going to 73.5mm. These 73.5mm pistons from Hepolite are great for street and mild racing. Top ring is 1.47mm height second ring is also 1.47mm Oil ring is 4mm in height 73.mm bore size is 2.8973", Pin height is 1.4875. Top 2 rings are 1.5mm height (.0591"), oil ring is 4mm (.1575") Pin Height- 1.47"