Patrese debuts Arrows A1-06 Ford at Kyalami, South African GP 1979. Q8 and 11th in the race won by Gilles Villeneuve’ Ferrari 312T4 (Schlegelmilch)
What’s it like livin’ and lovin’ the most successful race engine ever built?…
Our ‘Racers Retreat’, Peter Brennan owns and cares for ‘DFV250’. I have decided in fact he is a ‘perick’! Not only can he drive ‘big cars’ very quickly but he can also reconstruct, rebuild and maintain the things which makes him a multi-talented ‘perick!
Pete Brennan in the Arrows at Phillip Island, Paul Faulkner’s ex-Jones ’81 Williams FW07 behind (Brennan)
Villeneuve and Patrese, 7th and 5th in the 1979 Belgian GP at Zolder. Ferrari 312 T4 and Arrows A1 ’06’ May 1979 (unattributed)
‘DFV250’ sits in the back of his Arrows A1-‘06’. It was Ricardo Patrese’s car for the early season races in ’79 before Arrows switched to the more advanced but unsuccessful A2 which was not Tony Southgate’s best work. A1-06 was then sold for Aurora Series and Historic F1 use, eventually ending up in the Al Copeland Collection from whom Pierre acquired it after Copeland’s passing.
We will get to restoration of the Arrows and the Ford DFV which was at the ‘dismantle, crack-test and reassemble’ end of the spectrum rather than the ‘reconstruct around the monocoque bulkheads, four corners and ‘box’ huge task which Lola T330 ‘HU18’ represented, soon. Click on this link for a series of articles on that mammoth job which shows Peter’s talents.
For now I just want to focus on the care and maintenance of a DFV race to race which I expect is rather more involved than that of my ‘Peter Larner Engines’ 105bhp Formula Ford ‘Kent’ moteur?
Clark on the way to the DFV and Lotus 49’s first win, Dutch GP, Zandvoort 4 June 1967. Clark leads Brabham Brabham BT19 Repco 2nd, Rindt Cooper T81B Maserati DNF and Hulme Brabham BT20 Repco 3rd (Schlegelmilch)
Why the DFV you ask?…
Keith Duckworth’s Ford sponsored 1967 3 litre, 4 valve, fuel injected, 2993cc V8 is both the most successful grand prix engine of all time with 155 championship GP wins from 1967-1983 but also part of the winningest ‘family’ of engines. The DFV spun off the 3.9 litre Le Mans winning endurance racing ‘DFL’ and single turbo-charged 2.65 litre ‘DFX’ Indy victor.
Theo Page cutaway of the Ford Cosworth DFV in 1967. All the key elements referred to in the text covered in this superb drawing
Phil Reilly Engineering…
Brennan has tackled all manner of race engines over the years including lots of Chevs, Repco Holden F5000, Repco Brabham V8’s and various Coventry Climax FPF’s, but the DFV was new to him. His ‘guru’, a source of advice from afar and the fellow to whom he sent the his heads was Phil Reilly who has forgotten more about these engines than most people ever knew. His ‘shop, well known to American enthusiasts is in Corte Madera, California. Reilly Engineerings ‘Care and Feeding Your Cosworth DFV’ and Peters practices in looking after ‘250’ form the basis of this article.
Butt shot of one of the Lotus 49’s upon debut at Zandvoort 1967, ZF 5 speed ‘box, the ratios of which could not easily be changed about to be swapped. Shot shows the brilliant packaging of the DFV. Lotus’ Chapman prescribed a stress bearing V8 to Keith Duckworth inclusive of the way he wanted to attach the engine to the chassis at the bulkhead aft of the driver. Note the tubular brackets either side of the Borg and Beck clutch to which the suspension mounts. Their is no tubular frame or monocoque structure aft the driver, the engine itself forms the function of being the bit to which other bits are attached! Part of the brilliance of the DFV is its combination of power, weight, reliability and cost, the other aspect is the way it integrates with the chassis (Schlegelmilch)
DFV’s and DFV’s…
The development of these engines has effectively never stopped, you can still buy the bits from Cosworth Engineering, inclusive of a new engine should you buzz it to 15000rpm on an errant downchange and pop a rod or three thru its slender aluminium or magnesium flanks.
The DFV in Jim Clark’s winning Lotus 49 at Zandvoort on 4 June 1967 gave a smidge over 405bhp, its power delivery in the early days quite ferocious, coming in with a bang all up top, making it a bit of a challenge for Messrs Clark and Hill. A long stroke, same as Jims, engine like DFV250 gave around 470bhp and 260 lbs/foot of torque at 10500/9000rpm respectively whilst being thrashed to within an inch of its life by Patrese in early 1979.
A wrong turn of phrase really as the talented Italian multiple GP winner was both mechanically sympathetic and great test driver.
Jacky Ickx, Ensign N177 Ford, Monaco GP 1977, 10th in the race won by Scheckter’s Wolf WR1 Ford (unattributed)
All go and no show Cosworth Engineering. Subtle stamping of engine number in the engines valley (Brennan)
In fact when ‘250’ was first born it was a Cosworth lease engine used by Team Ensign and supplied to them on December 3 1976.
It was fitted to the N177 chassis’ driven by Jacky Ickx and Clay Regazzoni, multi GP winners both, during 1977. Without the teams records its not possible to know into which chassis ‘250’ was installed race by race.
Launch of the Arrows A1 at Silverstone in late 1977, maybe they figured the white body against the white snow would disguise its similarity to the new Shadow DN9, the design drawings of which Southgate erroneously thought were his! Patrese in car, Jack Oliver behind left and Tony Southgate at right. The High Court writ was shortly ‘in the mail’ (unattributed)
The engine was then bought by Arrows when the team spun out of Shadow. Jackie Oliver, Alan Rees, Tony Southgate and Dave Wass all felt they could ‘build a better mousetrap’ and left Don Nichols outfit at the end of 1977. The High Court legal stoush about ‘IP infringement’ which followed is a story for another time; in some ways Nichols had the last laugh as Shadow won a GP, the 1977 Austrian when Alan Jones took his first win in an a DN8 Cosworth, whereas Arrows never did win one albeit the business lasted a lot longer than Shadow…
(Brennan)
The Calm Before The Storm…
Here is ‘250’ all ready to rock on Peter’s dyno; ‘It takes about a day to plumb the thing up, its godda be done very carefully of course. Cosworth prescribe very fully how to do it (see below) Having gotten thru all the preliminary stages of running it in, i gave the thing ‘a tug’. All was okey-dokey for a bit and then all hell broke loose, a huge bang and then schrapnel everywhere!’
‘Thank christ it wasn’t the engine itself. The DFV’s vibrate so much it broke the dyno driveshaft @ 9200 rpm precisely! I have had all manner of donks on that dyno, over 500bhp Chevs etc but nothing has done that before. Having had that happen i still haven’t given it a full power run on the dyno anyway!’
But we are getting ahead of ourselves, the rebuild of the engine itself we will cover in an article about the car.
Brennan’s dyno driveshaft after Cosworth assault @ 9200rpm (Brennan)
Cosworth’s dyno running in procedures dated 31 October 1977 (Cosworth)
DFV use in Modern Times…
Phil Reilly; ‘If you rev the engine to 10800/11000rpm as Messrs Hunt, Fittipaldi and Jones did you will get the sort of engine bills Messrs Mayer, Fittipaldi and Williams paid!’
‘The DFV with an 11000rpm rev limit is a 3-4 hour motor…which will blow up big-time every now and then…needing an injection of $10-15K of parts and lots of (expensive) TLC…for vintage events use 10000rpm as a normal shift point. Doing this keeps the engine well below its stress point yet still provides enough power to test any drivers skills…the bonus is the engine will live 15-20 hours between rebuilds’.
Geoff Richardson Engineering have been looking after the engines since their heyday, James Claridge provided their perspective; ‘The routine rebuild interval for an engine limited to 10000rpm is approximately 1000 miles’.
‘This would comprise of us stripping it down, crack testing components, inspection of all parts, followed by re-assembly and dyno testing. Replacement of valve springs happens every time.Possible replacement of pistons depending on condition, if they were re-used they would certainly be replaced at 2000 miles. The same applies to all of the valves, they are taken on condition. New con-rod bolts are fitted, all new bearings, a new set of piston rings, and all new seals and O-rings are fitted. Nearly all the other parts are taken on condition and replaced accordingly’.
‘An engine with no issues or catastrophes that we knew the history of and is well looked after might cost somewhere in the region of £12-15000.00 to completely refresh’.
Peter Brennan provides the drivers perspective; ‘ The DFV has three quite distinct phases of power, one bangs in at 5500rpm, the next at 7000, then it goes ballistic at 9000 and all you do is chase gears with the tach going bananas…’ ‘Its not that difficult to get off the line, it obviously doesn’t have 500 plus foot pounds of torque like an F5000, sliding the foot sideways off the throttle at around 8000 rpm and then modulating it to match wheelspin with circuit grip soon has you motoring in the direction of tomorrow pretty smartly!’
Click on this footage of Brennan in the Arrows at the Adelaide Motorfest in 2014, the event uses part of the Adelaide GP circuit and some other streets.
‘The howl of the thing at 10000rpm as it yelps its way from cog to cog along the main straight at Phillip Island; with a 22/24 top fitted, fifth is 183 mph @ 10000rpm is unbelievable and Patrese would probably take it flat! Its not to be believed and relished every time you do it, Southern Loop comes up all too soon, its not the seagulls you are focused on as you turn the thing in believe me’.
Bruce Allison in the March 771/781 Ford, Thruxton or Oulton Park in 1978 (Allison)
Bruce Allison raced Cosworth powered March’s in the Aurora Series in 1978 ‘The record of the engine speaks for itself, it will still be popular in historic racing in 50 years! The engine was powerful, smooth and reliable the cars of course handled better with far less weight at the back than the F5000’s i was used to. The 781 March may have been the 782 with a DFV shoved in it but it was a beautiful handling car, the 761 chassis i used early in the season was not as good but the engines were always great, beautiful to drive’.
Lookin’ After Cossie: These things are like a mistress, stunning to look at but always wanting attention, never happy and a constant sap of cash…
Brennan’s sense of humor never too far from the surface! ’06’ at Sandown historics 2014. Dissertation on the chassis and suspension i will save for the article on the car itself. Shot included to show just how much the engines compact size, packaging and stress bearing nature assists the chassis designer. Compare how Tony Southgate mounts his suspension to the engine via these fabricated aluminium plates compared with Chapman’s tubular structures in the Lotus 49 of 1967. Note back of sparkbox in the Vee, ‘two towers’ behind that to connect with air scoop to cool inboard mounted rear discs, rear suspension outta the airsteam and clear of G/E tunnels, single support for gold rear wing, oil cooler and black painted starter motor with drive going forward (Bisset)
Storage and Fuel System.
The engine needs to be turned over by hand one revolution each week. Turn on the fuel pump as well, this will ensure no two valve springs remain fully compressed for too long and will circulate fuel through the metering unit to prevent corrosion and keep all the seals from sticking in one place.
The fuel filter needs to be changed every 500-700 miles, the engines have a high pressure pump to start and a mechanical one for normal on circuit running. The engine won’t run below 2000 rpm on the mechanical one, the electric one is needed for starting, fuel pressure of 120psi needs to be maintained at all time, at least 95 psi is needed to fire her up.
‘250’ ‘right bank’ showing both the auxiliary drive belt housing (right) and the super clever oil scavenge/de-aerator pump at left and one of the water pumps in between. The black coupling between oil and water pumps is called an ‘oldham drive’, a flexible joint (Brennan)
Olio.
A more critical liquid than fuel is oil. The engine must be plumbed to Cosworth specs…its data sheet DA0626 for ‘DFV250’ and the like. Its critical the engine never sucks air, at high revs bearing failure will result. At 10000rpm the engine is rotating at 166 times plus per second.
Peter; ‘I use Kendall 20/50 mineral oil, which has a high zinc content which is great for the cams and followers’. The Cosworth oil filter (Part #PP0404) needs to be changed every 300 miles, the oil level needs to be checked religiously as the engine uses as much as 4 quarts every 100 miles.
Oil temperature should be 90-100 degrees centigrade measured at the inlet to the pressure pump. 7000rpm should not be exceeded before the oil is at least 50 degrees centigrade.
‘250’ ready to be refitted to ’06’ in Brennans eastern Melbourne workshop. Note spark box between the Vee and behind it the fuel metering unit below the ‘aeroquip’ lines, Lucas injection of slide as against butterfly type. ‘Knurled wheel’ beside rear LH injector sets mixture, ‘behind’ this is the drive for the mechanical tach. Line at far right is cable drive for electro-mechanical fuel pump. The more you look the more elegant the packaging of it all is (Brennan)
Spark.
‘250’ has the Lucas ‘Opus’ system which has a pickup on the crank which fires the Opus at 38-40 degrees BTDC. The Opus also has a retard mechanism which is set for starting at 12 degrees BTDC.
The DFV has an alternator which provides sufficient power as long as the electrical fuel pump is switched off, DFV pilots need to remember this as they zap away from pitlane. ‘Pump Off’ was a familiar pit signal for decades!
Ignition timing is set on the dyno and is usually impossible to change in the chassis. Opus runs at 38-40 degrees BTDC, the sytem needs to be mounted in a cool place, the stock Cosworth mounting between the injection trumpets is usually fine.
The engine must be connected to negative earth with rev limiters set to 10400rpm.
The plugs are 10mm Bosch surface discharge to special order. Warm up plugs aren’t required, with plug life 3-4 race weekends. The plug wells need to be blown out, the HT leads removed with pliers. Plugs are tensioned to 9-10 foot pounds having been coated with ‘Copaslip’ first.
Spark boxes are delicate devices, you will kill them by voltage spikes caused by breaking the earth, so be clear on shut down procedures.
Throttle linkage of Brennans Arrows at Sandown 2014, ’06’ about to fired up. Note the ‘Opus’ spark box between the injection trumpets and black electro-mechnical fuel pump atop the centrally mounted, between driver and engine, fuel cell. Note radiator header tank and cap, bottom right is roll bar support bracket (Bisset)
Mechanical Installation.
The valve cover engine mounting bolts are 5/16 inch UNF and should be tightened to 16-18 ft pounds, be careful not to over-tighten to avoid cracking or deforming the magnesium casting.
The engine throttle slides have four over-centre return springs at the rear, these are a unique Cosworth invention which both reduces pedal pressure and ensures the slides close fully when you lift your foot. But they are not the throttle return springs which sould be well designed and of the ‘compression type’.
‘The Bomb’; Distributor cap missing at left, alternator in the middle and fuel metering unit at right, This is driven by a quill shaft off the complex gear set (shaft is only 6mm in diameter and designed to snap in cold weather rather the metering unit itself!) (Brennan)
The system needs to be cleaned and lubed regularly. The metering unit fuel cam should be flushed with aerosol ‘brake clean’ and carefully lubricated with a dab of ‘Copaslip’ before each event. If the fuel cam mechanism is gummy it will cause the throttle to seem to stick on.
‘250’ this time showing the ‘left side’ of the engine with combined water pump and oil pressure pump/filter assy. 250 engine a ‘twin water pump long stroke engine’ as against later ‘slim line’ from circa 1980 which only had one water/oil pump to maximise the space available for ground effects tunnels (Brennan)
The cooling system must not trap air, use bleeds as required, the system uses a 15-20psi cap. A 50/50 mix of water/glycol keeps corrosion in check and lubricates the water pump. Temperature strips should be used to monitor ‘real’ engine temperatures. The water outlet temps at the back of the heads should be 90-110 degrees centigrade and inlet temps 70-80 degrees.
‘250’ during its disassembly. Complex gear train to drive 32 valves, with degree plate to record engine valve timing during disassembly as a matter of record (Brennan)
Fuel & Fuel System.
Peter uses 100 octane avgas. Light engine oil is always added to the fuel to increase the life of the metering unit, fuel pumps and valve guides/seats. 20/50 Kendall is used, the ratio 2 ounces to 5 gallons of fuel.
The Lucas system needs 120psi to operate properly. Individual injector nozzles should seal at 50-65psi and thus not leak when the electrical pump is switched on, some leakage at 100psi plus is not unusual but it shouldn’t be pissin out…
The metering unit cam is set to run at specific clearances, typical DFV settings are .006 inch idle and .078inch wide open, these settings are 1 notch from full lean. These settings will be on the engine build sheet, check them periodically.
The mechanical fuel pump seal should be lubricated every 500 miles
Cosworth DFV and its constituent parts (unattributed)
Trivial Pursuit Question?
The firing order is; 1-8-3-6-4-5-2-7
Cold Weather Operation.
Clearances in the metering unit are so tight that in cold weather the quill drive or the metering unit drive will break. Not a good idea.
In weather below 45 degrees fahrenheit the engine shouldn’t be spun over before warming the metering unit with either a hair dryer or judicious amounts of boiling water being poured over it.
Firing Her Up: The Good Bit.
Warm up plugs and oil heaters aren’t needed, so some of the theatre of a bygone era is lost!
Make sure Arrows isn’t in gear!
Set the fuel cam datum pin to full rich
Switch on the electric fuel pump
100psi of fuel pressure should be present
Crank the engine over for 8-10 seconds with the throttle full open
Then prime each injection trumpet with a delicate squirt of fuel
Hit the Opus system retard switch (switch back across for on circuit work)
Switch on the ignition
Hold the throttle open about 25%, start the engine, but don’t race it as it fires. Hold her steady above 2300rpm, savouring the beautiful music it plays, settle the revs wherever the mechanical chatter is minimised but @ around 2300rpm
Its important not to run the engine below 2000rpm as the cams are not properly lubricated below that
Once the engine settles down with a little temperature switch off the electric fuel pump.
As the engine warms, the engine should be leaned one datum pin down, one notch at a time. With each notch it will spit and crackle a bit until it warms to it.
Engines are set normally to run one notch from full lean, they will be ‘grumpy’ at low speed which is normal.
Oil pressure should be 40-60 psi, make sure your driver has a look every now and then on circuit!
Unsurprisingly running a DFV is more complex than its Ford ‘Kent’ little brother! If the maintenance regime is followed and the driver keeps the engine in its optimum band and doesn’t buzz it on the down-changes, something Ricardo did during his Arrows days according to Tony Southgate then ‘DFV250’ will last around 1700-2000 miles between rebuilds…
DFV Engine in the Ground Effect Era…
Credits & Bibliography…
Peter Brennan many thanks
Phil Reilly Engineering, Geoff Richardson Engineering
Dossier on Arrows A1-06 written by Alan Henry for oldracingcars.com
Rainer Schlegelmilch
Tailpiece…
primotipo... 
Another great article Mark. Thanks!
BTW, the photo of Bruce Allison in the March – I don’t think there is anywhere at Thruxton that would would have looked like that.
Oulton Park may be possible – perhaps the Shell hairpin if they had but a barrier up to stop people driving into the lake – but it looks more like the hairpin at Mallory Park to me – albeit the “wall” does not seem very tall.
Thanks Grant, Bruce wasn’t sure! I will change the caption accordingly ,m
“before Arrows switched to the more advanced but unsuccessful A2 which was not Tony Southgate’s best work.”
Now there’s an understatement!