Procomp Electronics billet main caps are precision CNC-machined from superior-quality 1025 billet steel. They come available as stock replacements (straight bolt) or with splayed outer bolt holes. The splayed caps feature 10 degree angled outer holes to positively reinforce and tie the block together. These extreme main cap sets consist of the center four caps. Procomp Electronics billet main caps improve reliability in highly stressed engines by reducing distortion of the main bearing bores, and increasing the cap's resistance to closing up under high loads.
Speedmaster's precision Engine Block Main Caps are CNC-machined from 1025 billet steel and are offered as straight bolt stock replacements or with splayed outer bolt holes. The splayed engine main caps contain 10 degree angled outer holes that positively reinforce and tie the block together. Speedmaster billet steel engine main caps are used to improve reliability by reducing main bearing bore distortion, and increase resistance to closing up when the engine is under a high load. Speedmaster Engine Block Main Cap Sets contain the center three caps.