The Cosworth Ford DFV V8

Cosworth DFV Engine Specifications: The Cosworth DFV is a 90° V8, 4-stroke cycle, DOHC 4-valve/cylinder, even-fire, water-cooled, gasoline fuelled, race engine designed to be a stressed member of the chassis. It has 3550 parts.

The Cosworth DFV (Dual Four Valve) V8 engine for Formula One ("F1") cars was based on the FVA (Four Valve series A) development motor which was based largely on the Ford Cortina road car engine (Kent) block for Formula Two racing. The FVA and DFV were developed under the same contract from Ford, which provided the financing. The DFV shares a number of internal sizes with the FVA, which was completed first and served as the 'proof of concept' of the DFV design.

Designer(s): primarily Keith Duckworth (1933-2005) of Cosworth Engineering in 1966/1967 under contract to the Ford Motor Company (Mike Costin and Keith Duckworth were the principals in the formation of Cosworth in London, England in 1958)
First production: 1967
First Race: Dutch Grand Prix, Zandvoort, Netherlands, June 4, 1967: two entered, finished 1st (Jim Clark), DNF (Graham Hill, who was on pole).
Last Race: still active in historic and vintage racing.
Capacity: 182.6 in3 / 2993cc (to meet the 3 litre displacement limit in Formula One implemented starting in 1966)
  • 408 brake horsepower @ 9000 rpm (debut - 1967)
  • 439 hp (1970)
  • 450 hp @ 10500 rpm (minimum - 1973 spec.)
  • 465 hp (1977)
Torque: 245 ft·lb @ 8500 rpm (minimum - 1973 spec.)


Description: 90° V8 crankcase and cylinders cast together in aluminum. Wet cast iron cylinder liners sealed with O-rings. Steel, coated iron, and nikasil alloy liners were also tried. Nikasil alloy liners saved 8 lb in overall engine weight, and were standard by 1983.
Weight (with clutch): 370 lb / 168 kg
Overall width: 27.0" (686 mm)
Overall length: 21.5" (545 mm)
Bore: 3.373" / 85.674 mm
Stroke: 2.555" / 64.8 mm
Bore spacing: 4.100" / 104.1 mm
Deck height: 6.505" / 165.2 mm (crankshaft centerline to deck surface)
Crankshaft height: 5.23" / 132.8 mm (crankshaft centerline to external sump bottom)
Cylinder stagger: 0.375" / 9.5 mm (left ahead of right)
Materials: Cast aluminum block and head, forged steel crank and rods (earliest DFV cranks were billet), forged aluminum pistons, cast magnesium covers.
Firing order: 1-8-3-6-4-5-2-7
Compression ratio: 11.0:1 (approx.)
Fuel: 101 octane (M.M. - motor method) minimum
Rotation: clockwise when viewing front of engine
Mounting: At the rear end of the engine are suspension attachment points, and at the other are car attachment points at the top and bottom of the engine. The top chassis mounting bolts are part of the cam cover, and have 4 to 6 bolts per cover per end. The lower mounting bolts are part of a bracket bolted to the sump assembly. The lower bolts are located 9.0 inches (22.86 cm) apart. As the engine expands when it gets hot, the mountings are made so that the sheer forces are concentrated on the bottom bolts.
Serial numbers: The block serial numbers in the early years reflected the year the engine was built as the first digit, with two more numbers to indicated the unit number for that year. For example, DFV 701 was the first DFV built in 1967 and DFV 910 was the 10th DFV built in 1969. At a later date (likely circa. 1977 after 260 DFVs had been made) Cosworth went to sequential serial numbers; e.g. DFV 400 was the 400th DFV made (for Albert Obrist/Mario Hytten around 1986/87).


Description: single plane ("flat") common throw (2 rods per crank pin, no offset), forged nitrided steel (earliest cranks were billet steel), 5 main bearing crankshaft, hollow crank pins, weight 32 lbs / 14.5 kg, thrust taken on #3 main bearing, 8 bolts on flywheel flange.
Main journal diameter: 2.3755" to 2.3750" / 60.3 mm
Rod bearing diameter: 1.9370 to 1.9375" / 49.2 mm (same as Cosworth FVA: Bearing is Cosworth part number FA0067)
Connecting rod journal diameter: 1.9375" / 1.9370"
Crankshaft: End float: 0.004" / 0.009"
Connecting rod side clearance (big end): 0.006" / 0.012"

Piston :

Description: forged aluminum, 4 valve notches. Full floating wrist pin.
Piston compression height: 1.469 / 37.3 mm
Weight: ~328 grams (with rings, without pin)
Ring width: Piston ring gap (all rings): 0.017" to 0.022"

Connecting rod:

Description: forged steel, H-beam, fully machined connecting rods.
Bolts: 3/8" UNF
Connecting rod length: 5.23" (132.842 mm)
Wrist Pin length: 2.500" (63.5 mm)
Wrist pin diameter: 0.812" (20.638 mm)
Wrist pin end float: 0.000" ± 0.001" (retained by clips)
Rod/Stroke ratio: 2.05

Cylinder Heads:

Description: Cast aluminum, dual over head cams (DOHC), 4 valves/cylinder. Central spark plug in pent-roof combustion chamber. Each cylinder head has a stub shaft for cam drive gear on one end. The cylinder heads are interchangeable left and right.
Fastening: 18 retaining fasteners per head - 6 surrounding each cylinder - 10 studs from block, 8 studs from head.

Locating method: Cylinder heads are located by concentric hollow dowels on upper, outermost block studs.
Port flanges: Intake and exhaust flange have 4 bolts per port. Intake flanges ~20° from horizontal. Exhaust flanges are perpendicular to deck (i.e 45° from vertical). Intake and exhaust ports merge before port flange.
Cam carrier: Separate carrier for two camshafts per head (braced for carrying additional stressed member loads), attached to head with 20 studs (10 central long studs, 10 lateral shorter studs that also fasten the outside of the cam bearing caps). The camshaft bearing caps are also held by 1 additional bolt (or stud and nut) per cap (5 per camshaft, 20 total) to the camshaft carrier.
Camshaft cover: Has spark plug access ports and flange for mounting engine/suspension (4 @ 5/16" UNC). Mounting holes for tub and rear suspension are on 1.00" (25.4 mm) centers. Cover mounts to cam carrier with 28 screws/nuts. 4 additional screws fasten to the cam gear cover at the front of the head. Initial covers were marked "FORD" in plain lettering (shown below). Later versions had the Ford oval (an ellipse surrounding a fancy script "Ford" - the famous 'blue oval') or the word "Cosworth" cast into them.

Sealing: O-rings - 3 water passages per cylinder (1 on intake side, 2 on exhaust side), 2 oil drain back passages (in lower corner of heads), cylinders sealing with O-rings.


Description: dual overhead cam (DOHC), direct acting bucket-tappets, 4 valves/cylinder, gear driven from front of crankshaft.
Valve inclination angle (from centerline of bores): intake: 16° from cylinder axis; exhaust: 16° from cylinder axis, 32° included angle
Intake valve diameter: 1.32" / 34.5 mm (x2 per cylinder)
Exhaust valve diameter: 1.14" / 29.0 mm (x2 per cylinder)
Intake stem diameter: 9/32" ? / 7.14 mm
Exhaust stem diameter: 9/32" ? / 7.14 mm
Intake Valve center lines: 1.50" / 38 mm apart
Exhaust Valve center lines: 1.35" / 34 mm apart
Valve timing: Inlet valves fully open: 102° ATDC
Exhaust valves fully open: 102° BTDC
Valve lift: 0.410" (10.41 mm), less tappet clearance
Tappet clearance (Cold): Valve Springs: dual concentric variable-pitch coil springs on each valve. See drawings numbers DA 0622, DA 0623, DA 0624 and DA 0625 for identification and fitting details of valve spring arrangements. Any cylinder head may be fitted with any arrangement, since no change in machining details is involved, but it is not recommended that different arrangements be used on the same cylinder head.

Cam and Auxiliary Gears:

Description: 14 gears in 11 groups. Where a gear cluster is stacked and turns together, these are identified by an A,B,C... notation, where A is the gear closest to the front, B is second closest to the front, and so on.

(above illus.)
Color Code
(above illus.)
Number of Teeth
Crankshaft Gear1yellow27 teethclockwise, 1 x crank speed (keyed to crankshaft)
Transfer Gear Cluster2Ayellow36 teethcounter-clockwise, drives gear 2B at 27/36 = ¾ crank speed
2Bred28 teethcounter-clockwise, ¾ crank speed, drives gear 3B
Auxiliary Gear Cluster3Bred42 teethclockwise, 27/36 × 28/42 = ½ crank speed, fixed to 3A and 3C, also drives alternator/distributor, and fuel injection through a quill shaft, as well as the toothed belt auxiliary drive
3A & 3Clight grey34 teethclockwise, fixed to 3B, ½ crank speed. Gear 3A (front) drives the left side camshafts, gear 3C (rear) drives the right side camshafts
Primary Camshaft Transfer Gear (x2)4light grey38 teethcounter-clockwise, 27/36 × 28/42 × 34/38 = 44.7% crank speed
Secondary Camshaft Transfer Gear (x2)5dark grey60 teethclockwise, 27/36 × 28/42 × 34/38 × 38/60 = 31.7% crank speed
Cam Gears (x4)
Intake inboard,
Exhaust outboard
6dark grey34 teethcounter-clockwise, 27/36 × 28/42 × 34/38 × 38/60 × 60/34 = ½ crank speed

Auxiliary Drive: Drives the water, oil and fuel pumps from the #3 cam drive gear using a triangular arrangement of toothed gears with 24 teeth each and a flexible cogged rubber belt behind a cover at the front of the engine:

The belt is retained laterally by flanges on the upper gear.

The Lucas fuel metering unit, alternator, and distributor between the cylinder banks are driven from the gear #3 cluster at ½ engine speed via a ½" (12.7 mm) axillary 'quill' shaft that runs through the middle of the valley, very near the stiffening web that is cast in. This shaft drives a 26 tooth spur gear mounted in a housing between and slightly below the alternator and fuel metering unit. The spur gear attached directly to the quill shaft then drives a 26 tooth driven gear also between the alternator and fuel metering unit, but directly in line with them. As a result these driven items run counter-clockwise. The quill shaft was specifically designed in the first years of the DFV to reduce harmonic vibrations in the gear train that were breaking gear teeth.

Cylinder Numbering:

The right bank of cylinders are numbered 1 to 4 from front to back, the left bank are number 5 to 8:

Cooling system: The engine block is lock cooled first, then the heads. Two centrifugal water pumps, one on either side of engine (driven by the auxiliary drive), pump water into the sides of block. It passes from the block to the head through three passages around each cylinder - 2 near the exhaust ports, one near the intake port. Water exits the heads through a flange in rear face of each head to an external thermostat and then flows to the radiator(s).

Oil system:
Description: Dry sump with twin scavenge pumps (right side) and a single rotor pressure pump (left side). Main/rod bearings are fed from a large diameter gallery on the left side of the valley. Heads are fed from this gallery (left head) and another smaller oil passage on the right side of the valley (right head).
Oil sump: Cast aluminum with three integral main caps (for main bearings #1, #3, and #5), water crossover passages, and oil passages. Retained by 18 perimeters studs, plus two main studs each on #1, #3 & #5 main bearing bulkheads. Each of the #1, #3, #5 bulkheads also has a locating dowel. (Main caps #1 and #4 are retained by 4 studs each.) The sump is designed to be a stresses member of the engine/chassis.
Oil pumps: External (scavenge pump on lower right side of engine, pressure pump on lower left side of engine), belt driven at ½ engine rpm by toothed belt auxiliary drive.
Oil filter: Use only the approved Cosworth paper element (part number PP 0404) or equivalent.

Description: Lucas OPUS (Oscillating Pick-Up System) electronic (thyristor) ignition with conventional distributor mounted in valley (behind the fuel metering unit and alternator, rearmost of valley accessories). Access to distributor cap above bell housing. Conventional coil mounted above distributor in valley.
Firing order: 1-8-3-6-4-5-2-7
Spark plugs: Autolite PG 403 or Champion G56R (10 mm - originally intended for motorcycle applications) or equivalent. Before removal, clear all dirt from spark plug recess in head. Use special pliers to remove spark plug (high-tension) leads, do not pull directly on leads. Always put a small amount of graphite grease (or equivalent) on spark plug threads before installing them.
Trigger: 40 tooth wheel and variable reluctor sensor pickup mounted on front of crankshaft.
Ignition timing: Ignition timing is set at 7000 rpm, and should be approx. 35° BTDC. This should not be altered, but if it has for any reason:

  1. Unscrew the banjo on number 1 cylinder fuel outlet and carefully remove the banjo body from the fuel metering unit. Note: when replacing, this should be tightened to 90 to 100 lb·in (sealed by O-rings).
  2. Remove excessive fuel and turn the engine in the direction of normal rotation (clockwise as seen from the front) until the inner rotor port just starts to crack open. This point should be 30° ATDC for the number 4 cylinder firing.
  3. Fit the distributor rotor arm shaft with the slot at the bottom one of the two positions possible.
  4. Fit the distributor housing, turn the engine backwards 90° to 100° and then forward again, to take up the timing gear backlash, to 35° BTDC (the engine flywheel is marked T.D.C 30°, 35° and 40° BTDC, the reference point being the crankcase/sump split line on the right hand side of the engine).
  5. Fit the distributor drum so that the red spot is in the nearest of the four possible settings to the mark on the distributor housing near the L.T. electrical leads outlet.
  6. With the drum clockwise against the natural spring pressure in the fully advanced position, slacken the three distributor housing lock nuts and rotate the housing until the timing marks on the drum and casing line up exactly.
  7. Tighten the lock nuts in this position; any slight adjustment may be made by means of the adjuster screw mechanism on top of the housing.

Oil system: See Drawings: DA 0506 and DA 0626. 1971 engine are fitted with a new type of oil scavenge pump (part number KK 0084), which requires some new pipe work as shown on drawing DA 0626.

Oil Pressure: 70 psi minimum when hot to 80/90 psi at normal running speeds.
Care must be taken to allow the engine oil to reach 50°C (122°F) before exceeding 7000 rpm as bearing failure may result from running at high speeds with cold oil.

Maximum oil temperature: 100°C/212°F (measured in the oil tank).

If oil pressure cannot be maintained at above 70 psi using Cosworth approved oil, it is possible that too much air is being drawn from the oil tank, and the de-aerating system on oil returning from the scavenge pumps to the reservoir should be improved.

Oil tanks should allow for approximate consumption of 3 quarts (2.8 liters) during a Grand Prix race distance (~300 kilometers)

Fuel Injection System: Lucas Mk1 timed mechanical fuel injection, 1 injector per cylinder positioned upstream of slide throttle, fuel distributor gear driven from crankshaft, fuel pump driven by axillary drive on lower right side of engine. Fuel injection timing: cylinder number 1 starts to inject at 30° ATDC for cylinder number 4 firing. Since cylinder #4 is 360 degrees later than #1 in the firing order, this will be 30° into the intake stroke of cylinder #1, long enough to ensure there won't be any significant raw fuel out the exhaust due to valve overlap at normal operating speeds.

The fuel cam is set to the correct angle during assembly and test, and should not be altered. See auxiliary data sheet for alternative fuel cams at high altitude circuits: D50151

The mechanical pump drive shaft seal must be lubricated each time the engine is installed, via the hole on the tope of the drive shaft housing sealed by the small plastic plug. Oil should be gently fed into this hole until it comes out of the other small hole ½" away. Replace the plug afterwards.

Electrical systems:
Alternator: 12 Volts, 9 Amps
See Drawing: DA0471 and DA0359
The engine must be connected to a negative ground (earth) system.
All electrical connections should be covered with dielectric silicon grease, this is especially important when the engine will be operated in wet conditions.

Throttle linkage: Each brass ball joint (Cosworth part number PP 0251) is especially assembled to its control rod so that the ball is held captive in the joint. It is imperative that a control-rod is not unscrewed from its ball-joint. We advise that the joints be regularly lubricated with oil. 1974 engines are fitted with special steel ball joints (Cosworth part number DA 0638). These are assembled for minimum "play" when new, and lubricated with Anti-scuffing paste. After some use they may require to be re-adjusted and re-lubricated: we recommend that new split pins be used on re-assembly. 1975 engines have steel ball joints. DA 0781 LH thread and DA 0782 RH thread If spares are required for the throttle-linkage, it is important to specify the type of ball joint (brass or steel) in use.

The four throttle return springs are not designed to return the cable, pedal, etc. and these will require supplemental springs to suit each installation.

General: The engine must not be allowed to idle under 2000 rpm at any time or else excessive cam and tappet wear may result.

The rev limit is governed by the DA0471 Thyristor Speed Limiter control system which is set to cut spark if the engine speed rises above 10500 rpm. When driving, the maximum engine speed should not exceed 10500 rpm at any time (including downshifts).

If a "Smiths Chronometric" tachometer-head is fitted, the specification for the head is "4:1 clockwise".

Summary of drawings:
DA0662 Engine General Assy (2 Sheets)
DA0643 Wiring Diagram Thyristor
DA0774 Starter Assy DA0625 Valve Assembly (German)
DA0327 Fuel System DA0653 Exhaust System
DA0626 Oil System DA 0724 Cooling System

Cold Starts and Warm-Up:

Cold Ambient Temperature Starting Caution: Some fuel metering unit failures have been caused by attempting to start the engine in very cold weather. When the engine temperature is below 5°C (41°F), the metering unit should be warmed before any attempt is made to rotate it.

To start the engine:

  1. Set mixture datum pin to full rich,
  2. Switch on the electric fuel pump,
  3. Fully open the throttle,
  4. Crank the engine with starter motor for 3 to 4 seconds, then continue to crank and
  5. Ease off the throttle to approximately 1/3 open and switch on ignition while engine is still being cranked.
  6. Close throttle when engine starts,
  7. Verify that the oil pressure has risen, and adjust the rpm using the throttle to approx. 2300 rpm (±50 rpm) and hold steady at this speed, or an engine speed near this which gives a minimum mechanical clatter.
  8. Switched off the electric fuel pump, since the mechanical pump is designed to take over at above 2000 rpm. If this procedure had been followed, serious engine failures may be averted since failure of any one of the auxiliary pumps is usually due to mechanical fuel pump failures, which stop the engine.
  9. As soon as the water temperature gauge needle has moved off its stop, at about 30°C (86°F), increase the engine speed to between 4000 rpm and 4500 rpm, choosing a point where clatter is minimized. Turn the mixture adjusting datum pin to the middle notch to lean mixture.
  10. Keep the rpm steady till water temperature reaches 60° to 70°C (140° to 160°F) and oil temperature is rising,
  11. Engine is ready for the track.

Disassembly and Assembly Notes

It is very important that a torque wrench be used for all assembly work.

Camshaft Removal and Replacement:

  1. Remove the breather (pre-1970 engines),
  2. Remove the tachometer drive,
  3. Remove the spindle and cam covers,
  4. Remove the camshafts from one bank at a time:
When replacing the cam shafts, make sure marks line up as described above, and that the gears mesh as the cam is lowered. Note that the cam must be torqued down evenly.

Alternator/Distributor/Metering Unit Removal:

Before the cylinder heads can be removed, the alternator/distributor/metering unit assembly must be removed.
The engine should be rotated until top dead center T.D.C. with cylinder number 1 firing (all valves closed on cylinder #1). The ¼" UNC plug near the alternator air-inlet gauze should then be removed, and the engine turned slightly so that the nearest gap between the alternator drive gear teeth is directly below this plug hole. A pointed ¼" UNC screw should then be used to lock the gear in position. Take care not to rotate the engine while this screw is in place, or serious damage will occur. Mark the position of the flywheel so that the distributor assembly may be replaced in the same position. Remove the high-pressure fuel pipe linking manifolds, throttle cross shaft etc. After removing the four retaining screws, the unit may be removed by sliding it off the quill shaft splines towards the rear of the engine.

On re-assembly it is imperative that the distributor unit is replaced with the correct splines in engagement or the fuel and ignition timing will be wrong. Use anti-seize paste on splines.

Do not disassemble the throttle assembly while the manifold is still on the engine, as there is considerable danger that some rollers may fall into the inlet manifold.

The center distance of the timing gears is very critical, and nothing should be done which might affect this. If the idler gears are removed, it is essential that they go back on the same bank, otherwise the gear's backlash may be altered and this could cause gear failure.

Cylinder Heads:

The cylinder head side stud nuts must be loosened before the main head nuts are loosened. The cylinder head nuts must be loosened gradually and evenly, starting from the center and working towards the outside. The same procedure must be followed for the cam covers and crank case lower-half stud nuts.

Head and Sump Fastener Tightening Sequence:



Take care that all O-rings used in the assembly of the oil pressure pump and scavenge pump are in place, the correct size, and properly located. Take particular care when fitting the O-ring to the oil pressure pump inlet flange. Damage to this O-ring can allow air to be sucked into the oil, which will give low oil pressure readings and possibly lead to engine bearing failure.
When refitting cylinder heads, make sure that all O-rings and seals are in place, especially the O-ring between the head and cam carrier for camshaft oil feed. New compression seals should be used on re-assembly.

The special washer part number DA 0272 must be used the flat face against the magnesium cam cover.

Crankshaft Bungs
If the crankshaft oil galleries are threaded, a steel bung should be used, part number DA 0605 (see special data sheet B50219)
Later crank shafts have plain reamed galleries. The earliest of these have 5/8" diameter reamed galleries and use bungs with part number DA 0634 (or DA 0635) and circlips part with number PP 0981. Later crank shafts have 15mm diameter reamed galleries and use bungs with part number DA 0645 with circlips with part number DA 0652.

Tool No MT 0247 is required to insert and extract bungs (part number DA 0634, DA 0635 and DA 0645).

Assembly Torque Specifications:
Engine oil on thread and under the head, unless otherwise stated.
Main bearing stud nuts (6 external)50 ft·lb Initially for seating, then 43 to 45 ft·lb 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)43 to 45 ft·lb
Main Cap Side Stud Nuts 5/16"13 to 14 ft·lb
Main Cap 7/16" UNC screws53 to 55 ft·lb
Main Cap Side 5/16" UNC screws18 to 20 ft·lb
Connecting Rod Bolts41 to 42 ft·lb Anti-seize compound should be used under head of bolt, and engine oil on the threads
Cylinder Block Side Stud Nuts13 to 14 ft·lb, cadmium plated
Sump Side Plate 10-32 UNF screws25 in·lb, use Loctite B under head
Cylinder Head Stud Nuts48 to 50 ft·lb
Cylinder Head Side Stud Nuts13 to 14 ft·lb, cadmium plated
Cam Cap Stud Nuts13 to 14 ft·lb
Cam Carrier Cover Stud Nuts16 to 18 ft·lb
Cam Cover 10-32 UNF Screws32 to 35 ft·lb
Flywheel Bolts53 to 55 ft·lb
Clutch Bolts13 to 15 ft·lb
Front Engine Mounting 5/16" Screws18 to 20 ft·lb
Front Engine Mounting 3/8" Screws34 to 36 ft·lb
Metering Unit Outlet Banjo Bolts90 to 100 ft·lb
Injectors6 ft·lb
Spark Plugs9 ft·lb, use graphite grease under head and on thread
Oil Filter Bowl4 to 6 ft·lb after initial tightening to 10 lb·ft and slackening
Mechanical Fuel Pump Check Valve Housing8 ft·lb
Alternator Drive Quill30 to 32 ft·lb, use Loctite A under head and on threads
All ¼" UNC Socket Head Cap Screws46 to 48 in·lb
Engine mountingsThe top mounting 5/16" UNF bolts should have washers (part number DA 0017) against the magnesium cover, carefully tightened to 16 to 18 ft·lb 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

©2008, 2009 L.S. Gardiner. All rights reserved.

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