Reinforced ARP cylinder head studs FORD Pinto 2.0

The engines concerned

Ford's 2.0-litre Pinto is a 1,993 cc in-line four-cylinder (90.8 mm bore, 77 mm stroke) with eight valves and an overhead camshaft. It powered the Ford Sierra, Capri, Granada and Escort RS 2000 from 1972 to 1993.

As standard, the cylinder head of the Pinto 2.0 is secured by cylinder head bolts, which the ARP studs replace.

Reinforced ARP cylinder head studs

Every combustion cycle pushes the cylinder head upwards. The head fasteners resist it by keeping a constant clamping pressure on the gasket; if that pressure drops, the seal is no longer guaranteed.

The 151-4201 is an 8740 kit, 12 mm in diameter. According to its instruction sheet, the studs are screwed into the block by hand before the head is fitted, then the nuts are tightened in three equal passes, once the threads, washers and nuts have been lubricated with ARP Ultra-Torque. Material of the fasteners: 8740, a chrome-molybdenum steel that ARP specifies at 200,000 psi tensile strength. Factory-fitted fasteners usually fall into classes 10.9 and 12.9, with 150,800 to 176,900 psi minimum tensile strength. In M12, 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.

According to the sheet, ARP thread sealer goes on the block-side threads when 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.

According to the instruction sheet, ARP lubricant is also applied to the washers, as on the threads.

Source of these values: ARP instruction sheet 151-4201, 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 151-4201 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
Block threads	Stressed at every tightening	Spared by hand-tight fitting

When studs become necessary

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

• Pinto 2.0 built for fast road, rally or track use (turbo, raised compression ratio)
• 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

Why is it the most cost-effective solution?

A standard Pinto 2.0 runs with a reserve sized for series output. As soon as a turbo, a higher compression ratio or a competition build pushes up cylinder pressure, the head and its gasket move to the front line. ARP 8740 studs keep the head pressed down with a steadier clamping load; stripping an engine for a blown gasket costs far more than this kit.