This piston assembly set of 4 is built to the high-compression specification of the Austin Healey 100M. Supplied in standard bore size, they deliver an approximate 8.6:1 compression ratio with the correct dished crown design used in factory 100M and Le Mans upgrades.
These pistons are correct for the following engines:
Exclusions: Not suitable for early BN1 3-bearing engines prior to chassis 221536, or for standard low-compression 100/4 engines unless converted to 100M specification.
Professional installation is strongly recommended. Ensure correct piston ring gapping, cylinder clearance checks, and careful fitting. To make the job easier and avoid ring damage, we recommend using a piston ring compressor tool (TOL111) during assembly.
Unlike generic alternatives, this piston set is engineered specifically for the Austin Healey 100M. It ensures the correct compression ratio, crown shape, and durability, making it the right choice for restorers and rebuilders.
Yes, each piston comes with a complete ring set, gudgeon pin, and circlips.
They deliver approximately 8.6:1 compression ratio, as used in the original 100M specification.
No. These are standard size pistons for blocks still within original bore tolerance. Oversize versions are available for rebored engines (+020, +030, +040, +060).
They do not fit early BN1 3-bearing engines before chassis 221536 or standard low-compression 100/4 engines unless converted to 100M specification.
8.6:1 HIGH COMPRESSION