Reinforced ARP cylinder head studs Honda F20C F22C

The engines concerned

This kit fits the 16-valve inline four-cylinder VTEC Honda F20C (2.0 litres) and F22C (2.2 litres) engines, fitted to the Honda S2000 (AP1 and AP2). ARP also lists it for F20C and F22C engines fitted with a K24 crankshaft, in 2.4-litre builds.

As built, the cylinder head is held by ten main bolts (part 90005-PCX-003). They are tightened to 29 Nm, then by 90° and by another 90°. This angle tightening permanently stretches these bolts.

Reinforced ARP cylinder head studs

The job of the head fasteners is to keep the cylinder head locked to the block despite the pressure inside the combustion chambers. They keep the gasket compressed; as soon as their clamping force drops, leaks appear between head and block.

ARP reference 208-4702 is the stud kit intended for these engines: 8740, 12-point nuts, M12 x 1.5 thread. According to the instruction sheet, the studs are screwed into the block by hand before the head is fitted; the washers and nuts come next, once the threads, nuts and washers have been lubricated with the ARP Ultra-Torque lubricant supplied, and tightening is done in three equal passes, in the manufacturer's sequence. ARP makes these fasteners in 8740, a chrome-molybdenum steel whose tensile strength reaches 190,000 psi. To put this figure in context, original engine fasteners generally belong to classes 10.9 and 12.9, whose minimum ranges from 150,800 to 176,900 psi. In M12 x 1.5, the 8740 studs hold up to 600 hp on this four-cylinder engine (calculated estimate).

Technical specifications

Tightening torque

The studs are fitted into the block by hand, without a torque wrench. For a permanent installation, the instruction sheet accepts thread locker, with tightening to be completed before it sets.

If necessary, the block threads are chased with the M12 x 1.5 ARP thread chaser (ref. 912-0007), as the instruction sheet provides.

Where studs open into the water jacket, the instruction sheet calls for ARP thread sealer on their block-side thread.

Final tightening is done in three successive stages, following the manufacturer's tightening sequence; these torque figures only hold with ARP assembly 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 208-4702, 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 208-4702 instruction sheet

Technical guide

To obtain the intended preload, ARP assembly grease must be present on the threads and under the nuts: the torque figures in the table are established with it.

The ARP brand

Founded in the early 1970s by Gary Holzapfel, who came from the aerospace industry, ARP (Automotive Racing Products) set itself the mission of eliminating engine failures caused by inadequate fasteners in competition. Its thousands of parts are designed and produced in California, in several material grades depending on the application.

Advantages over the original bolts

Criterion	Original head bolts	Reinforced ARP studs
Tightening method	Torque then angle (29 Nm + 90° + 90°)	Torque only, in 3 stages
Block threads	Stressed at every tightening	Preserved (stud fitted hand tight)

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:

• Output goes beyond stock, whether on a heavily tuned naturally aspirated engine or a boosted one
• 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

OEM reference: 90005-PCX-003

Why is it the most cost-effective solution?

On the F20C and F22C, the original head bolts are sized for stock output. As power climbs, they are the first to limit gasket retention. ARP 8740 studs provide a higher clamp load, for an outlay well below that of reworking a cylinder head, gasket and labour included.

Consider a reinforced head gasket

To get the most out of reinforced fasteners, pair them with a head gasket that withstands the same pressure. Here is the gasket we offer for this engine: