Buick 425 Nailhead Pistons

Sized for the '63-'66 Buick 425 Nailhead, this piston set uses a high-silicon A-332 aluminum casting at a 4.3125-inch bore, machined on modern CNC equipment for consistent dimensions across the set. What makes the set Each set is precision balanced and weight-matched, holding no more than an 8-gram spread from the lightest piston to the heaviest, which helps the rebuilt engine run smoothly at higher RPM rather than vibrating under load. Before you order Match your block to the '63-'66 Buick 425 Nailhead and confirm a 4.3125-inch bore before buying, since this set is machined to that specific size rather than a universal fit. Have an experienced engine builder handle installation, ring gap checks, and final balancing verification during assembly. Common questions What's the bore size? 4.3125 inches, machined specifically for the 425 Nailhead. How are the pistons balanced? Weight-matched to within 8 grams across the full set. What material are the pistons cast from? A-332 aluminum alloy, chosen for its high silicon content.