Reinforced ARP main studs for TOYOTA 2JZ Dart

The Dart iron block for the 2JZ

ARP lists this kit as "3.0L Dart 2JZ Iron Block": it is meant for the Dart iron block designed for Toyota's 2JZ, the 3.0-litre in-line six. Part number 203-5411 is specific to this block.

On this block, the crankshaft main caps are held by the studs in the kit, in place of the cap fasteners of a production block.

Reinforced ARP studs for main bearings

The bottom end rests on its main bearings: combustion after combustion, the loads coming from the connecting rods end up on them. Under this stress the main cap tries to move on its parting line, which eventually brinells the mating faces and distorts the bearing bore.

This kit contains ARP 8740 steel studs for the main caps of the Dart iron block, to be tightened with nuts. Fitting and tightening follow the instructions of ARP and of the block manufacturer. ARP makes these fasteners in 8740, a chrome-moly steel brought by heat treatment to 190,000 psi tensile strength; the threads are rolled once the treatment is complete. As a reference point, an engine's original fasteners generally fall into classes 10.9 and 12.9, whose minimum ranges from 150,800 to 176,900 psi. The kit strengthens the main cap fastening of a Toyota engine built on a Dart iron block; no strength figure is published for this part number.

Technical specifications

Tightening torque

Technical guide

For assembly, use the ARP assembly grease intended for the purpose rather than engine oil.

The ARP brand

Coming from the aerospace industry, Gary Holzapfel founded ARP (Automotive Racing Products) in the early 1970s to put an end to engine failures caused by weak fasteners in motorsport. The company designs and manufactures thousands of part numbers in California, in several material grades depending on the application.

Advantages over the original bolts

Criterion	Original main bolts	Reinforced ARP studs
Fastening method	Bolts tightened straight into the block thread	Studs set in the block, nuts tightened on the cap side
Cap guidance	Cap set down with no locating aid before tightening	Cap centred by the studs as it is fitted
Material	Manufacturer's standard steel	8740 chrome-moly steel

When studs become necessary

• 2JZ build on a Dart iron block, for track, drift or drag use
• High-output 2JZ, far beyond stock level
• Dart block being assembled, main caps to be secured
• Forged crankshaft, rods or pistons to fit on this block
• Main caps to be made safer before a competition season

Vehicle compatibility

Why is it the most cost-effective solution?

An engine built on an iron block loads its main caps harder. 8740 ARP studs cost little compared with a block and a crankshaft to replace.

Consider the crankshaft main bearings

A bottom end rebuild calls for new bearings. We offer the tri-metal crankshaft main bearings that match these engines: