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ACL trimetal connecting rod bearings Porsche 930 3.2 3.3 M64 3.6

ACL trimetal connecting rod bearings Porsche 930 3.2 3.3 M64 3.6

€99.28 (tax incl.)

€110.32 (tax incl.) -10%

Set of 12 trimetal connecting rod half-bearings for Porsche 930 and M64.

Brand and treatment: ACL Race
Compatibility: 911 Carrera 3.2, 911 Turbo 3.3, 911 (964)
Engine codes: 930.20 to 930.26, 930.60 to 930.68, M 64.01 to M 64.03, M 64.50
Available sizes: standard to +0.25 mm, increased-clearance version (HX)

6B2463H-STD

Choice Brand - Coating Anti-Friction :: ACL RACE - Without treatment

Choice Dimension :: STANDARD

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The Porsche 930 and M64 flat-six engines

The 930 is the air-cooled flat-six of the Porsche 911: 3.2 litres naturally aspirated in the 911 Carrera (930.20 to 930.26) and 3.3 litres turbocharged in the 911 Turbo (930.60 to 930.68). The M64 of the type 964 911 raises the displacement to 3.6 litres (M 64.01 to M 64.03, and M 64.50 for the 964 Turbo). ACL lists the same bearing set for all these engines: a single set covers the family.

From the factory, this engine is fitted with standard production connecting rod bearings, sized for the loads of the original engine: as soon as power, engine speed or boost pressure increase, they reach their limits.

Trimetal connecting rod bearings

A trimetal bearing stacks three layers: a steel back, a copper-lead intermediate layer with high load capacity and an anti-friction running surface that protects the journal. The complete set contains 12 half shells, six pairs for a six-cylinder engine.

Technical specifications

Fitment dimensions common to all references

ACL bearings
Crankpin Ø 54.971 / 54.990 mm
Housing bore Ø 58.000 / 58.019 mm
Width 17.8 mm

Reference	Brand and treatment	Size	Wall thickness (mm)
6B2463H-STD	ACL Race - Untreated	Standard	1.497
6B2463HX-STD	ACL Race - Untreated	Std, increased clearance (HX)	1.484
6B2463H-.025	ACL Race - Untreated	+0.025	1.510
6B2463H-.25	ACL Race - Untreated	+0.25	1.622

Running clearance

Running clearance is the space left between the bearing and the crankpin, permanently filled by the oil film.

With the engine running, the crankpin does not touch the bearing: it rides on this oil film, which takes the load. The clearance sets the film thickness. Too small, it restricts oil flow, raises the temperature and invites seizure; too large, it lets the oil escape, the film loses its load capacity and oil pressure falls. The right clearance combines sufficient lubrication with an oil film that keeps carrying the load.

Size / grade	When to choose it	ACL Race Series
Standard (STD)	Standard journal, not reground	0.057 to 0.068 mm
Increased clearance (HX)	Wider clearance: high oil flow, high rpm	0.082 to 0.093 mm
+0.025 mm	Polished journal	0.057 to 0.068 mm
+0.25 mm	Journal reground to 0.25 mm	0.057 to 0.068 mm

Checking on assembly: lay a calibrated strip (Plastigauge) on the journal, torque the rod cap to spec, then compare the crushed strip against the gauge to read the clearance.

Plastigauge

Order the Plastigauge →

Technical guide

The ACL connecting rod bearings shown here are trimetal bearings built for engine tuning and racing. They withstand far higher loads than a standard bearing and come in several sizes: the standard size, a +0.025 mm size for a crankpin that has only been polished, a +0.25 mm regrind size and the HX version with increased clearance for high-revving engines or engines needing a high oil flow. This range lets you refit a reground crankshaft without changing product line and match the clearance to the oil and use chosen.

The brand

Founded in Australia in 1949, ACL Bearing Company designs high-performance engine bearings. Its Race Series brings together precision trimetal bearings, offered in a wide choice of sizes and fitted to built engines around the world.

Vehicle compatibility

This connecting rod bearing set fits the 930 and M64 flat-six engines of the following Porsche models:

Brand	Model (chassis)	Engine code	Power	Years
PORSCHE	911 3.3 SC Turbo	930.60, 930.66	301 hp	1977–1987
PORSCHE	911 3.2 SC Carrera	930.20, 930.26	231 hp	1983–1989
PORSCHE	911 Convertible 3.2 SC Carrera	930.20	231 hp	1983–1984
PORSCHE	911 Targa 3.2 Carrera	930.21	207 hp	1984–1987
PORSCHE	911 3.2 SC Carrera	930.21	207 hp	1984–1987
PORSCHE	911 Convertible 3.2 SC Carrera	930.21	207 hp	1984–1989
PORSCHE	911 3.3 Turbo	930.68	286 hp	1985–1987
PORSCHE	911 3.3 Turbo	930.66	300 hp	1986–1989
PORSCHE	911 3.2	930.25	218 hp	1986–1989
PORSCHE	911 Convertible 3.2 Carrera Speedster	930.25	218 hp	1986–1989
PORSCHE	911 Convertible 3.2 Carrera Speedster	930.20	231 hp	1986–1989
PORSCHE	911 Targa 3.2 Carrera	930.25	218 hp	1986–1989
PORSCHE	911 3.3 Turbo	930.60	330 hp	1986–1990
PORSCHE	911 Convertible 3.3 Turbo	930.66	301 hp	1986–1989
PORSCHE	911 Convertible 3.3 Turbo Carrera	930.68	286 hp	1986–1989
PORSCHE	911 Targa 3.3 Turbo	930.66	301 hp	1986–1990
PORSCHE	911 (964) 3.6 Carrera 4	M 64.01	250 hp	1988–1993
PORSCHE	911 Targa (964) 3.6 Carrera	M 64.01, M 64.02	250 hp	1988–1993
PORSCHE	911 Targa (964) 3.6 Carrera 4	M 64.01	250 hp	1988–1993
PORSCHE	911 Convertible (964) 3.6 Carrera 4	M 64.01	250 hp	1989–1994
PORSCHE	911 (964) 3.6 Carrera	M 64.01, M 64.02	250 hp	1989–1993
PORSCHE	911 Convertible (964) 3.6 Carrera	M 64.01, M 64.02	250 hp	1989–1994
PORSCHE	911 (964) 3.6 Carrera RS	M 64.03	260 hp	1991–1993
PORSCHE	911 Speedster (964) 3.6 Carrera	M 64.01, M 64.02	250 hp	1992–1994
PORSCHE	911 (964) 3.6 Turbo	M 64.50	360 hp	1993

Why replace the bearings

A failing connecting rod bearing does not fail alone: it scores the crankpin, sends debris through the oil circuit and calls at least for a crankshaft regrind, when it does not also take out the rod and the block. On a built engine, a bearing set costs only a fraction of a regrind, and even less of a full rebuild: it is the cheapest part of the rotating assembly and the one whose failure costs the most.