Reinforced ARP bolts and nuts for OEM rods MITSUBISHI 6G72 6G74

The Mitsubishi 6G72, 6G72T and 6G74 V6 engines concerned

This kit is for the Mitsubishi V6 engines of 3.0 litres (6G72, 2,972 cc, and its turbo version 6G72T) and 3.5 litres (6G74, 3,497 cc), in single or double overhead camshaft versions, with 12 or 24 valves (141 to 324 hp). Since 1986 they have powered the Mitsubishi Pajero, 3000GT, GTO, Diamante, Magna, Verada, L200, Galant and Eclipse, as well as the Dodge Stealth, Stratus and Ram 50, the Chrysler Le Baron, Saratoga and Voyager and the Hyundai Galloper, Dynasty and Grandeur.

ARP offers this kit, like reference 107-6024, for the Mitsubishi V6 engines of 3.0 litres (6G72) and 3.5 litres (6G74): it replaces the original rod bolts, whose reference and diameter are not published.

Reinforced ARP bolts and nuts for connecting rods

At every engine revolution, the rod and piston assembly pulls on the rod cap, and only its bolts hold it against these inertia loads. The original ones are intended for stock power.

The 107-6004 kit and the 107-6024 bolts, both in 8740, are fitted according to a single ARP instruction sheet: it recommends measuring the stretch and gives the 54.2 Nm torque only for a fitting without a gauge. These bolts are made from 8740, a chrome-moly steel brought to 180,000 psi tensile strength by ARP's heat treatment; the threads are rolled afterwards. For comparison, classes 10.9 and 12.9 of original fasteners have a minimum of 150,800 to 176,900 psi.

Technical specifications

The ARP instruction sheet has the bolts pressed into the rods; the bore must therefore carry a chamfer wide enough to take the radius under the head.

Tightening torque and stretch

For this part, ARP favours tightening to a measured stretch, the key to an exact preload; torque is given only when no gauge is available. The figures in the table assume ARP lubricant.

The values above come from the ARP 107-6004 and 107-6024 instruction sheets applicable at the date of publication; they are authoritative in the event of any difference. Read the ARP 107-6004 instruction sheet; Read the ARP 107-6024 instruction sheet

The ARP instruction sheet does not require a thread locker for this kit; only ARP Ultra-Torque grease is applied, on the bolt threads as well as on the bearing face of the nuts.

According to the ARP instructions, the big ends must be checked and resized with the fasteners in place; plan a visit to a machine shop.

Measuring bolt stretch

Tightening to stretch means setting the preload on how much the bolt actually stretches, rather than on a torque affected by friction. With the bolt fitted, the dial gauge is placed on both its ends and the bolt is tightened until the stretch given in the table is read. It is the safest method on a highly tuned engine.

Technical guide

Torque and stretch figures are only valid with ARP assembly grease, applied to the bolt threads and to the bearing face of the nuts.

The ARP brand

ARP (Automotive Racing Products) came into being in the early 1970s, when Gary Holzapfel, who came from the aerospace industry, decided to tackle the engine failures caused in motorsport by inadequate fasteners. Today the brand produces thousands of part numbers in California for the cylinder head, the main bearings and the connecting rods, in materials suited to each application, with manufacturing known for its consistency.

Vehicle compatibility

Why is it the most cost-effective solution?

A 3.0 or 3.5-litre V6 worked hard on a climb, in a 4x4 or in a pickup, pulls on its rod bolts at every high-revolution moment, and the original ones are not meant to last under that load. A set of new bolts weighs little against the rebuild of a V6 that has thrown a rod.