Reinforced ARP bolts and nuts for OEM rods MITSUBISHI DODGE CHRYSLER PLYMOUTH MAZDA FORD LONSDALE G54B 4G54 4G54B

The Mitsubishi 2.6 G54B engine concerned

This kit is for Mitsubishi's 2.6-litre four-cylinder with eight valves and a single overhead camshaft, known by the codes G54B and 4G54 (2,555 cm³, 94 to 155 hp). From 1977 to 1997 it powered the Mitsubishi Sigma, Magna, Verada, L200, Pajero and Starion, as well as their Dodge, Plymouth, Chrysler, Mazda B-Series, Ford Courier and Lonsdale YD twins.

This ARP kit takes the place of the original rod bolts of the G54B, whose reference and diameter are not published; ARP intends this kit, like reference 107-6023, for the Mitsubishi 2.6-litre (G54B) four-cylinder.

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.

These two 8740 ARP references, the 107-6003 kit and the 107-6023 bolts, follow the same instruction sheet: ARP favours measuring the stretch, and gives its 54.2 Nm torque only when no gauge is available. 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

According to the ARP instruction sheet, the bolts are pressed into the rods: the rod bore needs a chamfer large enough to clear the radius of the bolt.

Tightening torque and stretch

ARP gives priority to stretch control for an accurate preload; the torque in the table is used only when no gauge is available. Torque and stretch figures in the table apply with ARP lubricant.

The values above come from the ARP 107-6003 and 107-6023 instruction sheets applicable at the date of publication; they are authoritative in the event of any difference. Read the ARP 107-6003 instruction sheet; Read the ARP 107-6023 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.

Once the fasteners are fitted, the ARP instructions call for the big ends to be checked and resized by a machine shop.

Measuring bolt stretch

With the stretch gauge, you read directly how much the bolt stretches during tightening: the dial gauge sits on both ends of the fitted bolt, and tightening stops when the stretch reaches the value in the table. Friction no longer comes into play, hence a more consistent preload on a heavily stressed 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?

On a 2.6-litre pushed harder in a pickup or a 4x4, the rod takes a pull at every high revolution that the original bolt was not designed to withstand for long. Replacing the bolts before they fail costs far less than a new block, piston and rod.