Cosworth DFV (1968)
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Specifications

Cosworth DFV (Dual Four Valve)
Introduced in 1968
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Dimensions

Cylinders arrangement: V8 (90o)
Strokes: 4
Bore x Stroke: 86.674 mm x 64.8 mm, 3.412" x 2.551"
Capacity: 2993cc, 186.6ci
Compression ratio: 11.5:1 or 11.0:1

Construction materials

Aluminium alloy block with cast iron cylinder wet liners, 104.1 mm bore spacing, 165.2 mm deck height
cast Aluminium alloy cylinder-head Central spark plug in pent-roof combustion chamber
flat-plane forged nitrided steel crankshaft with 5 main bearings 60.3 mm diameter, 49.2 mm rod bearing diameter
Steel connecting rod length center to center 132.842 mm,
aluminium piston with 37.3 mm compression height, top ring 0.8 mm, middle 1.04 mm, oil 4.06 mm

Cylinder-head

Dual overhead camshafts (DOHC), gear driven
4 valves / cylinder - 32 valves total
intake valves inclination 16° from cylinder axis, exhaust valves inclination 16° from cylinder axis, 32° included angle
Intake valves diameter, 34.5 mm, with 38 mm center lines distance
exhaust valves diameter, 29.0 mm, with 34 mm center lines distance
valves stem, 7.14 mm

Aspiration

Natural with Lucas Mark II mechanical fuel injection

Ignition

natural aspiration with Lucas OPUS (Oscillating Pick-Up System) electronic (thyristor) ignition with conventional distributor with Autolite PG 403 or Champion G56R (10 mm)
Firing order, 1-8-3-6-4-5-2-7
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Cooling and lubrication

Water cooled
Dry sump

Torque values

Main bearing stud nuts (6 external) 68 Nm Initially for seating, then 58 to 61 Nm on final assembly (Note: the six external main-bearing stud nuts (on the sump bottom for main bearings #1, #3 and #5) should be tightened to a "seating torque", then backed off to release all torque, and finally re-tightened to the specified assembly torque.)
Main Cap Stud Nuts (on Tapered Dowel Type Studs) 58 to 61 Nm
Main Cap Side Stud Nuts 5/16" 18 to 19 Nm
Main Cap 7/16" UNC screws 72 to 75 Nm
Main Cap Side 5/16" UNC screws 24 to 27 Nm
Connecting Rod Bolts 56 to 57 Nm Anti-seize compound should be used under head of bolt, and engine oil on the threads
Cylinder Block Side Stud Nuts 18 to 19 Nm, cadmium plated
Sump Side Plate 10-32 UNF screws 34 Nm, use Loctite B under head
Cylinder Head Stud Nuts 65 to 68 Nm
Cylinder Head Side Stud Nuts 18 to 19 Nm, cadmium plated
Cam Cap Stud Nuts 18 to 19 Nm
Cam Carrier Cover Stud Nuts 22 to 24 Nm
Cam Cover 10-32 UNF Screws 43 to 47 Nm
Flywheel Bolts 72 to 75 Nm
Clutch Bolts 18 to 20 Nm
Front Engine Mounting 5/16" Screws 24 to 27 Nm
Front Engine Mounting 3/8" Screws 46 to 49 Nm
Metering Unit Outlet Banjo Bolts 122 to 136 Nm
Injectors 8 Nm
Spark Plugs 12 Nm, use graphite grease under head and on thread
Oil Filter Bowl 5 to 8 Nm after initial tightening to 14 Nm and slackening
Mechanical Fuel Pump Check Valve Housing 11 Nm
Alternator Drive Quill 41 to 43 Nm, use Loctite A under head and on threads
All ¼" UNC Socket Head Cap Screws 62 to 65 Nm
Engine mountings The top mounting 5/16" UNF bolts should have washers (part number DA 0017) against the magnesium cover, carefully tightened to 22 to 24 Nm to avoid collapsing the magnesium alloy.
On lower mounting points, flat washers of .060" (1/16") min thickness must be used under the chassis bolt heads.
The lower front mounting is marked "RT" (right top). If the lower front mounting is removed, it should be replaced with the letters "RT" towards the top of the engine.
See also drawing numbers DA 0662 and DA 0774

Engine oil on thread and under the head, unless otherwise stated.

Models used and Output

Year Model Induction Compression ratio Power Torque
1968 Ford F3L P68 Lucas Mk I 11.5:1 420 HP / 313 KW @ 9000 rpm 366 Nm / 270 ft lbs @ 7000 rpm
1970 McLaren M8C Lucas Mk II 11.5:1 420 HP / 313 KW @ 9000 rpm 366 Nm / 270 ft lbs @ 7000 rpm
1971 Ligier JS2 Lucas Mk II 11.0:1 420 HP / 313 KW @ 9000 rpm 366 Nm / 270 ft lbs @ 7000 rpm
1971 Ligier JS3 Lucas Mk II 11.0:1 420 HP / 313 KW @ 9000 rpm 366 Nm / 270 ft lbs @ 7000 rpm
1972 Lola T280, S12 Lucas Mk II 11.0:1 445 HP / 332 KW @ 10500 rpm 339 Nm / 250 ft lbs @ 8500 rpm
1972 Mirage M6, S12 Lucas Mk II 11.0:1 445 HP / 332 KW @ 10500 rpm 339 Nm / 250 ft lbs @ 8500 rpm
1973 Lola T282, S12 Lucas Mk II 11.0:1 445 HP / 332 KW @ 10500 rpm 339 Nm / 250 ft lbs @ 8500 rpm
1974 Mirage GR7, S12 Lucas Mk II 11.0:1 445 HP / 332 KW @ 10500 rpm 339 Nm / 250 ft lbs @ 8500 rpm
1975 Ligier JS2 S12 Lucas Mk II 11.0:1 460 bhp / 343 KW @ 10200 rpm 338 Nm / 249 ft lbs @ 8000 rpm
1975 Mirage GR8 Lucas Mk II 11.0:1 375 HP / 280 KW @ 9000 rpm
1976 Lola T286, S12 Lucas Mk II 11.0:1 445 HP / 332 KW @ 10500 rpm 339 Nm / 250 ft lbs @ 8500 rpm
1981 Lola T600, S12 Lucas Mk II 11.0:1 465 HP / 342 KW @ 10500 rpm 339 Nm / 250 ft lbs @ 8500 rpm
1982 Rondeau M382, S12 Lucas Mk II 11.0:1 465 HP / 342 KW @ 10500 rpm 339 Nm / 250 ft lbs @ 8500 rpm
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Drawings

CosworthDFVo4-www.ruiamaraljr.blogspot.com_.jpg Source
15.-Cosworth-Dfv-4.jpg Source
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