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Thread: Cosworth BDG info

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    Racer Decade Plus User Willid1's Avatar

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    Cosworth BDG info

    I found the following as a nice PDF file, but can't upload it.

    Has some nice do's and dont's that I think would apply to any engine. Was a bit surprised by the torque, no wonder they are always screaming.

    Surprised to see them recommending a "barseal" capsule added to each engine after a rebuild.

    There are a few line drawings but not very interesting.

    Cosworth BDG 1978 Engine Specification
    COSWORTH BDG 1978 ENGINE SPECIFICATION SHEET
    Capacity: 120.5cu. in Bore: 3.543? Stroke: 3.056?
    1975cc 90.0mm 77.7mm
    Compression ratio: 12.0 to 1
    H.P rating: 280bhp @ 9250rpm
    Torque: 175lb. Ft @ 7000rpm
    Cylinder numbering: Front 1 ? 2 ? 3 ? 4 Rear
    IMPORTANT DIMENSIONS
    Crankshaft: End float .002? / .011?
    Main bearing dia. 2.1260? / 2.1255?
    Crankpin dia. 1.9375? / 1.9370?
    Connecting rods: End float (big end) .004? / .012?
    Jackshaft: End float .003? / .007?
    Jackshaft part no. BA0502
    Jackshaft pulley is bolted to jackshaft with 1off bolt 3/8unc
    and 1off BA0510 washer.
    It is recommended that ?silastic? is used under the washer to
    prevent oil leaks.
    Oil pump: Backlash of oil pump gear .003? / .005?
    Timing belt tension: Taken on long slack side of 90 / 100
    belt with Burroughs gauge
    (see instructions).
    Gudgeon pins: End float .001? interference / .001? clearance
    Piston rings: Gaps on all rings .015? / .022?
    Valve timing: Inlet valves fully open 102o a.t.d.c. +1o (F1 cam)
    Exhaust valves fully open 110o b.t.d.c. +1o (BD4 cam)
    Lap pulleys onto cams. With timing set correctly and belt correctly tensioned, timing marks on
    pulley rim should line up horizontally in the centre of engine, when No. 1 piston is at t.d.c.
    firing. If the marks do not line up it is advisable to remark the pulleys so that the engine may
    be easily re-timed on rebuild.
    Valve lift: .410? less the tappet clearance. F1 inlet
    .432? less the tappet clearance. BD4 exhaust
    Tappet clearance: .009? / .010? inlet .012? / .013? exhaust
    (cold)
    Cosworth BDG 1978 Engine Specification
    Valve springs: Cosworth part no. PP1656 (pair of springs)
    Fitted length of outer 1.26? / 1.27?
    Free length of outer 1.44?
    Fuel injection timing: No. 1 starts to inject at 80o a.t.d.c with No. 4 firing.
    Ignition: Firing order 1 ? 3 ? 4 ? 2
    Lucas ?Opus? ignition with distributor fitted with Cosworth type solid mounted pick-up.
    Ignition timing is about 34o b.t.d.c. Timing is set on test with timing light at 7000rpm, and may
    vary slightly from engine to engine for maximum performance.
    Oil filter element: Part No. PP0404
    Oil system:
    See Cosworth drawing BA0330 for layout of recommended oil system, which shows oil pipe
    sizes etc.
    Note that pipes into the oil / air separator, built into the top of the tank, should enter
    tangentially with the oil scavenge pipe ahead of the engine breather pipe.
    Oil pressure when hot should be 70psi min. rising to 80 ? 90 psi at normal running speeds.
    Care must be taken to allow the oil temperature to reach 50oc before exceeding 7000rpm
    otherwise bearing failure may occur due to running at high speed with cold oil.
    Maximum permissible oil temperature is 100oc, measured in the tank.
    If the oil pumps are dismantled for any reason, it is essential to check that the shaft turns
    freely on re-assembly before fitting to the engine. If it is not possible to turn the shaft easily
    then the drive gears may suffer. Any dirt in the pumps will have a similar effect.
    Fuel Injection
    See Cosworth drawing BA0331 for layout of recommended fuel system.
    The metering unit fuel cam is set to the correct stroke during assembly, and the settings
    currently used are, .005in. stroke at closed throttle and .056in. stroke at full throttle, using fuel
    cam part number BA0456 and datum pin part number EA0230.
    These figures are achieved with the datum pin set at 1 notch from lean. The stroke should not
    be less than 0.56in. at full throttle otherwise piston life will be shortened. (NB. 8mm metering
    unit.)
    Full throttle position of the cam is when its straight edge is at 45o to the axis of the metering
    unit. At this angle the stroke should be adjusted, if necessary by shimming to give full throttle
    stroke as above. Then, with the metering unit mounted on the engine, the threaded rod
    should be adjusted so as to hold the cam in the 45o with the throttle fully open. From this
    setting one or two turns of the threaded rod will give the correct stroke at closed throttle.
    DO NOT open the throttle by moving the fuel cam.
    (NOTE: It is not necessary to have the cam at exactly 45o at full throttle since the cam gives
    constant stroke over a large number of degrees near full throttle)
    The low pressure ?Bendix? pump passes fuel around a primary circuit to supply fuel at a
    positive head to the high-pressure electric pump, (Cosworth part number DA8059).
    Cosworth BDG 1978 Engine Specification
    The Bendix pump should have a capacity of at least 20galls / hour at 1psi and be mounted as
    low as possible in the chassis.
    The high-pressure pump is to be mounted with its outlet union vertically upwards. Both the
    Bendix and the high-pressure pumps are to be left switched on whilst the engine is running.
    The de-aerator should be about 2in. dia x 6in. high (min) to allow air bubbles to rise to the
    surface and escape, thus providing air-free fuel to the high-pressure pump. Inlet and outlet
    unions should be arranged tangentially to induce a rotary flow in the fuel.
    Fuel should be 99octane (RM) min. and metering unit feed pressure should be maintained at
    120 / 140psi by adjusting the pressure relief valve if necessary.
    NOTE: Fuel pumps should be left on during short pit stops, to prevent fuel from evaporating
    from the metering unit thus possibly causing a failure of cable drive soldered joints, due to
    increased friction in the metering unit.
    Throttle slide:
    It is advisable to dismantle the throttle slide assembly whilst still bolted to the cylinder head
    otherwise balls and / or rollers from the slide bearing track may fall down the inlet ports. After
    removing from the cylinder head it may be carefully dismantled on the bench, noting the
    arrangement of the balls, rollers and spacers in the bearing tracks, in order that they are reassembled
    in the same sequence, as any change in the arrangement will result in slide
    inefficiency see drawing number BA0332. The nylatron packing on the right hand of the
    manifold should be positioned on re-assembly to give a slide opening of .030? and the screw
    tightened to trap the packing. This will give the throttle setting for idling. Ensure that the idling
    stop abuts to the slide over the full width.
    Electrical system:
    See drawing number BA0382.
    Current engines use PP1117 (Thyristor speed limiter) set to cut out at 9500rpm.
    The engine must be connected to a negative earth (ground) system.
    It is advised that all electrical connections are smeared wit silicone grease (we suggest
    Midland Silicones MS4) especially when the engine is operated in wet conditions.
    Spark plugs: Champion N54R or equivalent
    If cold starting proves difficult on N54R, a set of N61 may be used for initial warming-up but
    should not be used for racing purposes. Before removing plugs, clear all dirt from recess. Use
    special pliers to remove HT leads ? do not pull directly on the leads. Use graphite grease on
    plug threads and torque to 9lb. ft.
    Cooling system:
    Refer to drawing number BA0383.
    A ?barseal? capsule should be added to the cooling system each time the engine is fitted in
    the chassis. In cold weather the usual precautions should be taken against freezing.
    GENERAL INFORMATION
    Starting from cold & warming up:
    Cosworth BDG 1978 Engine Specification
    Set mixture datum pin to full rich, switch on electrical pump, fully open throttle and crank for
    three or four seconds with starter motor. Ease off throttle to approx. 1/3 open and switch on
    ignition whilst engine is being cranked.
    Reduce throttle opening when engine fires.
    Observe that oil pressure has come up, adjust rpm to 2300 and hold at this rpm or reading
    near this, which gives best running and minimum clatter.
    As soon as the water temperature gauge needle is off the stop i.e. 30oc increase rpm to
    between 4000 and 4500, again choosing a point which gives best running and minimum
    mechanical clatter. Turn mixture datum adjusting pin to middle notch to weaken mixture.
    Keep rpm steady until water temperature reaches 60 ? 70oc and oil temperature is rising. See
    also under oil system.
    Cold weather conditions:
    It has been found that some fuel metering unit failures have been caused by attempting to
    start the engine in very cold weather. We therefore suggest that when the general
    temperature is below 5oc the metering unit is warmed before any attempt at starting is made.
    Rev limits:
    Recommended limit is 9000rpm; 8.500rpm in first and second gears.
    Drivers should be aware that due to the tachometer reading lag it is quite easy to exceed
    8500rpm in low gears even though the tacho reading is well below 8500rpm. This is a major
    cause of engine failure. The engine must not be allowed to idle under 2000rpm or excessive
    cam and tappet wear may be experienced. ALSO SEE NOTE UNDER OIL SYSTEM ABOVE.
    Tappets:
    Standard tappets may be used, but the modification shown in the sketch below is
    recommended to avoid excessive wear of the tappet bores, or use:
    BA0276 Tappet piston ? exhaust side only
    FA0196 Tappet piston ? inlet side only
    Both of which are already modified.
    Camshaft oil seals:
    Cosworth part number PP5228.
    Cosworth BDG 1978 Engine Specification
    To prevent failure in service it is recommended that the garter spring is removed, the ends
    untwisted, de-greased and reassembled with Loctite 602.
    Cam carrier:
    It is recommended that ?silastic? is used to make as oil tight joint between the cylinder head
    and cam carrier and that the paper gasket is omitted.
    Belt tension and valve timing:
    All pulleys are to be sprayed with a.d.f. (air drying lubricant film ? molybdenum disulphide) on
    initial assembly.
    Belt tension should always be set with a cold engine. Tension is adjusted by moving the
    eccentric idler pulley.
    To check tension, turn engine in its normal direction of rotation to t.d.c. number 1 cylinder
    firing. Tension should be checked midway between the exhaust camshaft pulley and the
    crankshaft pulley. It is important that each time the tension is being adjusted and checked the
    engine is brought up to t.d.c. number 1 cylinder firing in its normal direction of rotation. It is
    essential that the belt is not over tensioned, as this will result in premature tooth failure.
    We recommend the use of Burroughs tension gauge BT 33-86F 4 ?18 and the tension should
    be set at 90 / 100 gauge reading. Alternatively a Gates tension tester may be used, and for
    ½? belt deflection a gauge reading of 11 / 15lbs should be obtained.
    On new engine build the camshaft pulleys are marked on the front rims on their horizontal
    centre line. These marks line up in the centre with the engine at t.d.c. number 1 firing. A
    further mark is on the rear rim of the exhaust camshaft pulley, which lines up with a scribed
    line on the cam cover, with the engine again set at t.d.c. number 1 firing. When checking the
    timing marks, or timings, always turn the engine in its normal direction of rotation, with the belt
    correctly tensioned.
    The camshaft pulleys are a taper fit on the camshafts, and have two ¼? unc tapped holes to
    facilitate removal. On new engine build the end of each camshaft and pulley hub face are
    scribed with a horizontal line in order that the pulleys can be re-fitted in their original position.
    Injection timing:
    Unscrew the banjo from number 1 cylinder fuel outlet and carefully remove the banjo body
    from the fuel metering unit. Remove excessive fuel and turn engine to normal direction of
    rotation until the inner rotor port just starts to crack open. This point should be 80o a.t.d.c.
    with number 4 cylinder on firing stroke.
    To re-time the metering unit, set engine at 80o a.t.d.c. Slacken exhaust camshaft retaining
    bolt and turn the metering unit drive pulley in normal direction of rotation until number 1 port
    cracks open. Re-tighten camshaft pulley bolt and carefully replace banjo.
    Tappet adjustment:
    Rotate engine forwards to t.d.c. (cam pulley marks lined up). Mark metering unit drive pulley
    to housing and remove belt. Remove main camshaft belt, having slacked off eccentric pulley,
    to remove tension from belt.
    (N.B. always re-fit belts to run in the same direction as before)
    Retain tappet up against the cams, preferably by inserting 8 spring clips between adjacent
    tappets. Remove surplus oil from tappet chambers with a syringe. Slacken off hex. Head
    bolts, ensuring cam carrier lifts evenly. Carefully lift cam carrier assembly vertically until clear
    of the valve stems and shims. Some shims may stick to the tappets and some to the valve
    stems. When re-building an engine it is advisable to stick the shims to the valve stems with
    Cosworth BDG 1978 Engine Specification
    grease, whilst carrying out tappet adjustments, to ensure the shim remains on the valve stem
    whilst removing the carrier.
    Cylinder head:
    Number bolts 1 ? 5 exhaust side, 6 ? 10 inlet side, then order of tightening is as follows:
    8, 3, 7, 4, 9, 2, 10, 1, 6, 5.
    Exhaust systems:
    With BA8128 trumpet assembly use 4 into 1 exhaust system made of SWG tube.
    4 x 2 1/8? o/dia. x 27? long into 1 x 2 3/4? o/dia. x 26? long.
    Running in:
    Standard running-in procedure on a dynamometer is as follows:
    Torque rpm time
    44lb ft. 3500 to full oil pressure
    52lb ft. 4000 30min
    70lb ft. 4500 30min
    88lb ft. 5000 30min
    105lb ft. 5500 30min
    Then inspect tappets and test.
    Related drawing:
    BA0335 Engine general assembly (2 sheets)
    BA0330 Recommended oil system
    BA0331 Recommended fuel system
    BA0332 Throttle assembly
    BA0382 Ignition and charging circuit diagrams
    BA0383 Recommended cooling system
    BA0543 Exhaust flange
    FA0289 Crankshaft bung assembly
    Bolt torques:
    Engine oil on threads and under head unless otherwise stated.
    Flywheel / crank (12 bolt) 3/8 unf 50 ? 55lb ft.
    Big end 41 ? 42lb ft.
    (anti-scuffing paste
    under head engine
    oil on threads)
    Cylinder head (soc cap hd) 7/16 unc 62 ? 65lb ft.
    (oil under head)
    Main cap 7/16 unc 65 ? 70lb ft.
    Cam pulley 3/8 unf 15 ? 20lb ft.
    Jackshaft pulley 5/16 unc 15 ? 20lb ft.
    Cosworth BDG 1978 Engine Specification
    Jackshaft pulley 3/8 unc 20 ? 25lb ft.
    (BA0509)
    Idler pulley nut 7/16 unc 30 ? 35lb ft.
    Crankshaft pulley 7/16 unc 35 ? 40lb ft.
    Cam carrier / cylinder head 1 /4 unc 8 ? 10lb ft.
    Clutch bolt nuts 5/16 unf 13 ? 15lb ft.
    Sparking plugs 10mm 9lb ft
    (graphite grease on
    threads)
    Other
    1 /4 bolts (sump, front cover etc.) 5 ? 7lb ft.
    5/16 10 ? 15lb ft.
    3/8 20 ? 25lb ft.
    Pistons ? 1975cc:
    (PA0112)
    Gap on all rings to be .015 / .022? when fitted in the bore.
    Pistons are normally supplied with gudgeon pins ground to the correct length and circlips
    ground flat and parallel. Circlips are to be fitted with their ground faces outwards and the
    gudgeon pin end float should be .001? interference to .001? clearance measured at room
    temperature.
    It is necessary to do a trial assembly to check the pistons for squish clearance at t.d.c. The
    piston crown should be .000 / .002? above the top face of the block at t.d.c. and it will be
    necessary to machine the piston crowns to achieve this figure.
    Pistons also require machining for gasket clearance, details of which are shown below:
    Cosworth BDG 1978 Engine Specification
    Cylinder block:
    The cylinder block should be finally cleaned before assembly. Main oil gallery bungs and the
    cam carrier / camshaft oil feed restrictor can then be fitted. The restrictor, part number
    BA0356, should be fitted flush to just below the cylinder block top face.

  2. #2
    Pit Crew Decade Plus User TepiTheFinn's Avatar

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    Re: Cosworth BDG info

    could you mail the .pdf- file for me
    Cheers,
    Tepi

  3. #3
    Racer

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    Re: Cosworth BDG info

    could you mail the .pdf- file for me
    Cheers,
    Tepi
    And me Please

  4. #4
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    Re: Cosworth BDG info

    try and upload it as an attachment

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    Racer Decade Plus User Willid1's Avatar

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    Re: Cosworth BDG info

    If this attachment doesn't work try

    http://www.cosworth.com/ Look in Heritage and data sheets

    David

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    Racer Decade Plus User Willid1's Avatar

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    Re: Cosworth BDG info

    Thank you Mr gaskin I will have to remember that in future .

    David

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    Re: Cosworth BDG info

    no Problem

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    Bodger headbolt's Avatar

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    Re: Cosworth BDG info

    great to find such an old thread but some fantastic info there

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    Re: Cosworth BDG info

    Hi
    sorry to resurrect an old thread but if you still have the pdf of this could you send it to me
    the sheets dont exist on cosworths site anymore
    thanks

  10. #10
    Spanner Monkey djaminhi's Avatar

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    Re: Cosworth BDG info

    Quote Originally Posted by Elliotwoodward View Post
    Hi
    sorry to resurrect an old thread but if you still have the pdf of this could you send it to me
    the sheets dont exist on cosworths site anymore
    thanks

    Just a suggestion.

    Maybe you can Copy and Paste the text into Word and then save as a PDF......
    Regards,
    Kevin

  11. #11
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    Re: Cosworth BDG info

    Quote Originally Posted by djaminhi View Post
    Just a suggestion.

    Maybe you can Copy and Paste the text into Word and then save as a PDF......
    I was hoping for the technical drawings as well that aren’t present here

    Thanks though

  12. #12
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    Re: Cosworth BDG info

    If you are willing to post your emailaddress here (you cannot send a pm with just 2 posts) then I can email it to you.
    But don't get excited about the drawings, there are just 3 of them, very basic stuff.

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