Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Piston Dimensions

Standard Sizes
Tolerance Group 0
Piston Size 99.98 ± 0.007 mm (3.936 in ± 0.0003 in)
Bore Size 100 ± 0.005 mm (3.937 ± 0.0002 in)
Tolerance Group 1
Piston Size 99.99 ± 0.007 mm (3.9366 ± 0.0003 in)
Bore Size 100.01 ± 0.005 mm (3.9374 ± 0.0002 in)
Tolerance Group 2
Piston Size 100 ± 0.007 mm (3.937 ± 0.0003 in)
Bore Size 100.02 ± 0.005 mm (3.9378 ± 0.0002 in)

1st Oversize
Tolerance Group 10
Piston Size 100.48 ± 0.007 mm (3.9559 ± 0.0003 in)
Bore Size 100.50 ± 0.005 mm (3.9567 ± 0.0002 in)
Tolerance Group 11
Piston Size 100.49 ± 0.007 mm (3.9563 ± 0.0003 in)
Bore Size 100.51 ± 0.005 mm (3.9571 ± 0.0002 in)
Tolerance Group 12
Piston Size 100.50 ± 0.007 mm (3.9567 ± 0.0003 in)
Bore Size 100.52 ± 0.005 mm (3.9575 ± 0.0002 in)

2nd Oversize
Tolerance Group 110
Piston Size 100.98 ± 0.007 mm (3.9756 ± 0.0003 in)
Bore Size 101 ± 0.005 mm (3.9764 ± 0.0002 in)
Tolerance Group 111
Piston Size 100.99 ± 0.007 mm (3.9760 ± 0.0003 in)
Bore Size 101.01 ± 0.005 mm (3.9768 ± 0.0002 in)
Tolerance Group 112
Piston Size 101 ± 0.007 mm (3.9764 ± 0.0003 in)
Bore Size 101.02 ± 0.005 mm (3.9772 ± 0.0002 in)