ARP Tools

ARP’s tools here are mostly for the moment the pistons go into the block. The largest group is ring compressors, each machined for a single bore size rather than adjustable, in inch sizes such as 4.020, 4.100 and 4.280 in and metric sizes from 75 to 100 mm, with tapered versions that guide the piston and rings in from the top of the bore. Choose the one that matches your finished bore rather than the nominal size, because a fixed sleeve only works when it is a close match.

Around them sit tools for preparing the block and checking fasteners: thread cleaning chaser taps from M8 to M12, which restore existing threads without cutting new metal; ring squaring tools that set a ring square in the bore so its end gap can be measured; and a stretch gauge for rod bolts that are tightened to a stretch figure rather than a torque value. Seal plates for particular blocks and a storage cabinet stocked with accessory bolts complete the section.

A chaser tap is not a cutting tap. Run it by hand with thread lubricant, and blow each hole clean before any stud or bolt goes in.