6112-4180 421 Pontiac Early and Late FX Series -7cc Flat Top Pontiac Early and Late Forged Piston Set 4.180 inch bore Pin Dia.: 0.98" Comp Height: 1.585" Piston Series Option:FX-2 2618 Alloy 943 pin pistons

943 pin pistons

447 Small Block Ford 351W

357 Small Block Ford 351C

37 Effective June 15th 2026

It can be done after the fact but pin fitting the pistons twice adds on quite a bit more labor

6112-4180 421 Pontiac Early and Late FX Series -7cc Flat Top Pontiac Early and Late Forged Piston Set 4.180 inch bore Pin Dia.: 0.98" Comp Height: 1.585" Piston Series Option:FX-2 2618 Alloy 943 pin pistons439 Pontiac Early and Late, FX, Comp Height: 1. 585, 7cc Flat Top , PIN: . 98", Full Floating or Press Fit, Ring Groove: 1. 2 1. 2 3MM, Stroke: 4. 000", ROD: 6. 625, Approx Comp Ratio: 62cc 12. 53, 87cc 9. 74, 124cc 7. 43 Effective June 15th 2026, These Pontiac ring grooves have been updated to the new specifications of 1. 2 1. 2 3mm. Parts manufactured prior to this date feature ring grooves with dimensions of 1 16 1 16 3 16.