Reinforced ARP cylinder head studs Honda Acura B17A B18A1 B18B1 B18C1 B18C5

The engines concerned

This kit fits the 16-valve inline four-cylinder Honda and Acura B-series engines of 1.7 and 1.8 litres: B17A1, B18A1, B18B1, B18C1 and B18C5, fitted notably to the Acura Integra.

On these B-series engines, Honda secures the cylinder head to the block with bolts; the ARP kit replaces them with studs.

Reinforced ARP cylinder head studs

Cylinder head fasteners work constantly: they hold the head tight against the block, crush the gasket to the right value and hold back the push of the gases at every combustion. If they lose even a little tension, the gasket starts to leak.

For these engines ARP offers a single stud kit, reference 208-4303, in 8740 with 12-point nuts and 7/16 in thread. According to its instruction sheet, the studs are screwed into the block by hand before the cylinder head is fitted; the nuts and washers, lubricated with the ARP Ultra-Torque lubricant supplied, are then tightened in three equal passes, in the manufacturer's tightening sequence. 8740 is a chrome-molybdenum steel, rated by ARP at 200,000 psi tensile strength. As a reference point, an engine's standard fasteners mostly belong to property classes 10.9 and 12.9, with a minimum tensile strength between 150,800 and 176,900 psi. In 7/16 in, the 8740 studs hold up to 600 hp on this four-cylinder engine (calculated estimate).

Technical specifications

Tightening torque

No torque is applied to the studs as they go into the block: they are screwed in by hand. The instruction sheet leaves the option of thread locker to mount them permanently, provided tightening is done before the product hardens.

Before assembly, the instruction sheet requires the block threads to be cleaned, if necessary with the ARP thread cleaning tool.

ARP thread sealer is only needed if the studs open into the water jacket.

Follow the tightening sequence recommended by the manufacturer and bring to torque in three stages; the stated values assume ARP lubricant on the threads and under the nuts.

The washers also receive ARP lubricant, as stated in the instruction sheet.

Source of these values: ARP instruction sheet 208-4303, revision current at the time of publication. The official instruction sheet applies if any discrepancy appears; it covers the entire procedure and the tightening sequence. Read the ARP 208-4303 instruction sheet

Technical guide

The stated tightening torques only make sense with ARP assembly grease, applied to the threads and under the nuts.

The ARP brand

ARP (Automotive Racing Products) was born in the early 1970s from the initiative of Gary Holzapfel, an engineer from the aerospace industry, determined to eliminate engine failures caused by weak fasteners in motorsport. The company designs and manufactures thousands of parts in California, in several material grades suited to each use.

Advantages over the original bolts

Criterion	Original head bolts	Reinforced ARP studs
Fitting in the block	Bolts tightened at every fitting	Studs screwed in by hand, with no tightening stress

When studs become necessary

Standard fasteners remain suitable as long as the engine keeps its original combustion pressure. They reach their limits in the following cases:

• Power exceeds stock output (strongly tuned naturally aspirated build or forced induction)
• Compression ratio raised for more power
• Reinforced MLS head gasket, which requires a high and even preload
• Cylinder head that has already lifted or gasket that has already leaked
• Racing or track use, with repeated heat-ups and frequent teardowns

Vehicle compatibility

Why is it the most cost-effective solution?

As soon as the build exceeds stock power, it is the original head fasteners that limit the engine: the gasket eventually loses its clamping pressure. A kit of ARP 8740 studs keeps a higher clamp load and costs far less than redoing a cylinder head, gasket and labour included.

Consider a reinforced head gasket

Reinforced fasteners are only fully worthwhile with a head gasket able to resist the same pressure. We offer the following parts for these engines: