Race-quality 72.5 mm piston for 1342cc big-bore engine conversion. Due to the increasing scarcity of 1300cc A and A+ series blocks, using a 72.5 mm piston as the first big-bore oversize effectively doubles the block's life. The 72.5 mm piston gives 1342cc, for nearly identical performance to the 1380cc, yet the block can be safely re-bored to 73 mm at a later date. Plus the 72.5mm bore fits the existing standard gaskets better. Using a 21.4cc chamber and the AF470 black head gasket, this gives just under 10:1 compression with the piston down the bore .007". With the pistons at zero-deck, it gives 10.4:1. Note the rings are supplied unfitted so they can be gapped to .011-.014" range after boring to 72.5 mm. Piston rings are slightly proud of the ring grooves in the piston, which is an unconventional configuration, but is a tested design.
Piston features high silicone content and advanced heat treatments which creates a more stable piston with less expansion under running conditions.
Sold each, with rings and lightweight pin included.