ARP Main Studs

ARP’s main-cap hardware comes as stud kits or bolt kits, with studs making up most of the range. A stud goes into the block first and the cap is clamped by a nut, so the thread in the block is not twisted as it is tightened. A bolt kit is the direct replacement for the factory bolts.

Beyond the engine family, the titles separate kits by the block’s layout: 2-bolt or 4-bolt mains, splayed outer bolts, iron or aluminium blocks, main girdles, and kits with longer studs for mounting a windage tray. Some engines also have side-bolt kits for cross-bolted caps, and several diesel engines are covered.

Most kits are 8740 chrome moly, with ARP2000 for some applications. The listings name the socket or hex key each kit needs, which matters because many studs are fitted with a hex key in the end.

A few kits are also listed for Nissan, Toyota, Honda and BMW models. Changing to studs can alter the main bearing bores, so plan for the block to be line-honed with the new hardware torqued in place.