Reinforced ARP cylinder head studs HONDA F20 F22

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

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.

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

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.

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 instruction sheet also calls for ARP lubricant on the washers.

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

All torque values on this page are given with ARP assembly grease on the threads and under the nuts; another lubricant would make them wrong.

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
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

The original fasteners are sized for the engine as it leaves the factory. They need to be reinforced when:

• Output goes beyond stock, whether on a heavily tuned naturally aspirated engine or a boosted one
• The compression ratio rises as the build progresses
• The original gasket is replaced by a reinforced MLS gasket, which requires a high and uniform preload
• The engine has already suffered a lifted head or a gasket leak
• Competition use imposes severe heat cycles and regular head removals

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: