ARP Valvetrain

ARP’s valvetrain parts are the fasteners on top of the head: valve cover bolt and stud kits, and rocker arm studs. The cover kits are chosen by the type of cover as much as by the engine. There are separate kits for stamped steel covers, cast aluminium covers and centre-bolted designs, because each takes a different length or style of fastener.

Each kit comes in a choice of finish and head. Stainless steel kits sit alongside kits in 8740 chrome moly, and either can be had with 12-point heads or hex. The product data lists the thread, most often 1/4-20, and the socket size, which helps when there is little room around the cover. Rocker arm stud kits are listed by stud diameter, such as 3/8 or 7/16 inch.

The kits are named for the engine or the cover they suit and are not linked to cars, so check the cylinder head and cover type before ordering. Some kits are made for particular aftermarket heads, blocks and covers.

Cover fasteners need only modest torque. Tighten them evenly from the centre outwards, since too much crushes the gasket and can distort an aluminium cover.