Replacement cast aluminum 4.1875″ bore piston set for ’59-’66 Buick 401 Nailhead.

Cast from high silicon A-332 aluminum alloy
Machined on modern CNC machinery
Precision balanced & weight-matched sets
Balanced to within 8 grams from the lightest to the heaviest piston
The 401 rings are a cast top, and a cast second ring.