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 403 Gen 5 LT Direct

403 Gen 5 LT Direct Injection

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

943 pin pistons

447 Small Block Ford 351W

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 403 Gen 5 LT Direct439 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.