primotipo…

Dan Gurney’s Lola T70 Ford during the Stardust Grand Prix, Las Vegas Can-Am round, 13 November 1966…

Gurney didn’t have a great weekend, the fuel injected Gurney Weslake aluminium headed Lola qualified eighth and failed to finish with a fuel tank breather problem. John Surtees won the race and the series in a Lola T70 Mk2 Chev. The photo got me thinkin’ about those cylinder heads…

The Gurney-Weslake combination is best known for the Formula 1 60-degree, DOHC, four-valve, Lucas injected V12 which was fitted into the gorgeous Eagle Mk1 created by Len Terry and Dan in 1966. Initially fitted with a Coventry Climax 2.7-litre ‘Indy’ FPF four cylinder engine, the V12 finally raced at Monza in 1966 and won its only GP at Spa in mid 1967. The F1 project resulted from the relationship which arose from the development of special cylinder heads for the pushrod small-block Ford V8 a little earlier.

Gurney was keen to better exploit the performance potential of the small-block 289 cid Ford V8 with which he was so familiar from his AC Shelby Cobra, Ford GT40 and Can-Am experiences.

This engine family was the same as that which provided the first 255 cid pushrod engines used by Team Lotus at Indy in the rear of Lotus 29s raced by Dan and Jim Clark in 1963. Whilst Dan’s plan was initially to get more competitive engines for the Sports Car Club of America’s burgeoning sportscar races – which would of course become the Can-Am Championship from 1966 – the Gurney-Weslake V8 engines ultimately powered winning cars at Le Mans and in Group 7 sportscar, ‘Indycar’ single-seaters and beyond.

Dan had seen what Keith Duckworth had done with pushrod Ford engines in the UK; development of 100 bhp per litre, and figured the same approach could be successfully applied to the Ford V8.

‘I heard that Duckworth had modified a four-cylinder Ford Anglia cylinder head by boring an inlet tract hole straight at the port, so it was a more direct shot and I believe that was the first time that a little four-cylinder 1000cc pushrod engine made 100 horsepower. It seemed to me to be a pretty neat thing to accomplish and, naturally, being inquisitive, I wondered if the same idea could be applied to a Ford V8, since it looked to me as though we could do something similar to the 289-302 style engine’.

‘Actually we began our inquest with an extensive rework of the existing 271 bhp heads. At the peak of our testing with the 271 bhp cast iron heads on a 325 inch block, we were pulling as much as 448 hp on gasoline. It was about this time we figured a few improvements along the lines of a new head design might give us even more power, so we got after it’.

Dan sought out Weslake Engineering just outside Rye near the East Sussex coast of England and via Production Manager Michael Daniel engaged them to do some drawings after Gurney delivered some 289 heads to be inspected, analysed and sectioned.

Patterns were made and these first Mark 1 Gurney-Weslake heads were cast at Alcoa Aluminium’s foundry in Pennysylvania.

They featured circular inlet ports that provided a direct path from manifold interface to valve seat in order to get as much fuel-air mixture as possible into the combustion chambers. The valves were inclined at 9-degrees to the cylinder centreline instead of the 20-degree angle of the stock Ford heads. The valve guides were fitted with Perfect Circle teflon valve seals. Classic Weslake combustion chamber shapes were deployed: heart shaped with precision machined valve seat inserts – steel for the inlets and bronze for the exhausts – both press-fits into the heads.

An immediate improvement of 70-100 bhp was achieved over the standard 289-302 heads both through the mid to upper rpm ranges without losing smoothness down low. To cope with the increased loadings the bottom end also ‘had a birthday’ with bits and pieces provided by well known suppliers of US performance gear.

The Dearborn Crankshaft Corporation made a steel crank to AAR specifications which sat in bearings donated by the Ford DOHC Indy motor. Carrillo provided shot-peened conrods to which were attached Forged True pistons; compression ratios ranged from 10.5 to 11.6 to one. Jack Engle worked on cam grinds arriving at solutions which involved short lift and long duration with ‘rev springs’ fitted into the block’s oil galleries to assist the proper seating of the valves at high rpm. Ford’s stock high pressure oil pump was man enough for the job with stock oil pans baffled and main bearing girdles added to keep the whole lot stable.

The Gurney-Weslake heads were first used by Dan during the 200 mile LA Times Grand Prix sportscar race at Riverside in late October 1965 fitted to his McLaren Elva Mk1

In an all-star cast which included Jim Clark, Bruce McLaren, Chris Amon, Hap Sharp, John Cannon, Peter Revson, Chuck Parsons, Jerry Titus, David Hobbs, Bob Bondurant, Parnelli Jones, Richie Ginther, Graham Hill, Jerry Grant, Walt Hansgen, and Dan (wow!- was there ever a better ‘Can-Am’ field of depth). That race was won by Sharp’s Chaparral 2A Chev from Clark’s Lotus 40 Ford and McLaren’s McLaren Elva Mk2 Olds. Dan’s AAR McLaren was out with brake troubles on lap 24. By that stage of G-W development Mark 2 heads were fitted which incorporated improvements including removable rocker arm studs.

Mark 3 Gurney Weslake heads were developed in 1966 with alterations to make assembly and maintenance easier.

With this configuration AAR took their first GW head win in the May 1966 United States Road Racing Championship round at Bridghampton. Jerry Grant won in the AAR Lola T70 Ford from Lothar Motschenbacher’s McLaren Elva Mk2 Olds and Mike Goth in a McLaren Chev.

The same chassis was used by Dan to win the Long Island, Bridghampton Can-Am round in September 1966. In a splendid weekend for All American Racers Dan popped the Lola T70 Mk2 on pole and won from the works McLaren M1B Chevs of McLaren and Amon. Sadly, it was the only Can-Am win for a Ford powered car; 495 bhp @ 7800 rpm was claimed at the time, ‘The redline used to be 8000 rpm but I just found I could turn 8900’ Dan quipped after the race.

It’s interesting to look at the engine competition at the time. Pete Lyons in his bible ‘Can-Am’ writes that ‘Chevrolet’s small block was the typical T70 engine of 1966, and those offered by well respected Traco Engineering in Los Angeles can be considered definitive. The bore remained standard at 4.0in but a stroker crank of 3.625in gave a displacement of 364.4 cid. Breathing thorough a quartet of two-barrel 58mm Weber side-draft carburettors…such a package was rated at about 490bhp at 6800 rpm and 465 lb/ft of torque at 4500…it weighed about 540-560 lbs. Price was just under $US5000’.

Towards the end of 1966 the engine was also fitted to the very first Eagle Indycar chassis – Mk2 ‘201’ which was raced by Dan in the ’66 Indy with a Ford 255cid DOHC motor. In fact Gurney didn’t complete a lap having been wiped out with eleven other cars in THAT famous collision.

In the re-engined Ford G-W 305 cid powered car Jochen Rindt contested the 1967 Indy 500, he qualified 32^nd and retired after completing 108 of the 200 laps with valve trouble – classified 24^th. His was the only 305 cid stock-block powered car in the field, the race was won by AJ Foyt, Coyote Ford from Al Unser and Joe Leonard in Ford engined Lola and Coyote respectively.

Further development work resulted in the Mark 4 variant which was lighter in weight with narrower rocker covers and an intake manifold inclined towards the engine centreline.

Into 1967 AAR’s Can-Am engine was based on Ford’s new ‘mid-sized’ block stroked to 377cid. Dan’s Lola T70 was often the best of the ‘non-McLaren M6 Chev’ class in a year of dominance from the Kiwi’s with their beautiful papaya cars; pole at Riverside was a standout.

Fitted with a Mark 4 engine, but 318 cid, gave Dan and the G-W engine’s first USAC win in the Rex Mays 300 at Riverside in November 1967. His Eagle Mk3 won from pole from the Bobby Unser Eagle Mk3 Ford Indy V8 and Mario Andretti’s Brawner Ford on the challenging 2.6 mile California road course. Gurney achieved six more USAC Championship wins over the next two years and finished second twice on the trot at Indy in 1968 in a Mk3 and in 1969 in a Mk7 ‘Santa Ana’.

Changes to USAC rules for stock-block engines ultimately allowed the G-W motors to displace 318 cid. On methanol they were good for 560 bhp @ 7500 rpm in 1968 with circa 600 bhp in 1969. On petrol a sprint 289 was good for as much as 506 bhp @ 7800 rpm, and a good 305 520 hp.

For the 1968 Can-Am AAR acquired a McLaren M6B and in a ‘lightness and dash policy’ took over 100 pounds out of the car with a cocktail of small-block 325 cid Ford G-W and the smaller, lighter Hewland DG300 gearbox. The track dimensions were narrower, the body lighter with a lower, longer nosepiece and suspension arms, exhaust system, gear linkage and bracketry were re-made out of titanium. The car was renamed McLeagle! It wasn’t enough of course, the Bruce and Denny M8A Chev 427 alloy blocked cars rolled over the top of the McLeagle, Lola T160, Ferrari 612P and all else in their path. Denny was Can-Am champ that year.

In 1968 and 1969 the John Wyer entered, Gulf sponsored Ford GT40 chassis ‘1075’ won the Le Mans classic fitted with Gurney-Weslake Ford engines.

The honours were taken by Pedro Rodriguez and Lucien Bianchi in ’68 and Jacky Ickx and Jackie Oliver in ’69. In 1968-69 despite the Mk1 GT40 hardly being in the full flush of youth, the gorgeous, somewhat heavy G-W engined machines won many endurance classics against more modern Porsche, Alfa Romeo, Matra and Ferraris (in 1969): the 1968 Brands Hatch 6 Hour, Monza 1000 Km, Spa 1000 Km, Watkins Glen 6 Hour and 1969 Sebring 12 Hour and Spa 1000 Km.

In period the Le Mans winning engines gave circa 440 bhp @ 6800 rpm: 302 cid Ford V8, Gurney Weslake heads fed by four Weber 48IDA carbs.

In a busy 1968 for AAR, in a commercial approach to capitalise on the cylinder head designs, Gurney started to make modified versions of the heads cast in LM8 aluminium by the Aeroplane and Motor Foundry in England for road cars.

The racer’s Hilborn fuel injection was replaced with a four-barrel carb. Anticipating a large order from Ford, the heads had detuned combustion chambers and were of a budget design. They could be machined with different sized ports and/or valve sizes to the specification of the full racing heads despite some of the internal passageways being of differing sizes to the race heads.

When no manufacturer (Ford or Lincoln/Mercury) chose to fit the heads Dan was left with an enormous stockpile of them. ‘It didn’t’ happen because no-one big enough got behind it. If someone like Henry (Ford II) would have said “Hey guys, why don’t you do this?”, that would have been all it would have taken’ offered Gurney. A trial assembly run was arranged by Gar Laux, head of Lincoln-Mercury but perhaps the idea fell foul of the ‘not invented here’ notion.

Many of the surplus heads were converted to as near as racing specifications as the Gurney factory could make them and were fitted to Indy cars. None of these heads were fitted in-period to GT40’s. All GT40 heads were made at the William Mills foundry and were a higher grade casting with the full race combustion chambers, porting and passageways. The Airplane and Motor cast heads were usually branded as Gurney Eagle although some will over time have been retro-fitted with Gurney Weslake rocker covers.

Into the 1969 Can-Am without the Ford factory support he hoped for, Dan raced the same McLeagle with a very special, aluminium 344 cid small-block Ford G-W.

Some of the Can-Am rounds conflicted with his USAC commitments, back at AAR the team toiled with a three-valve G-W variant to sit atop specially cast ally Ford blocks. After various development problems kept it off the tracks Dan bought a 7-litre Chev and popped it into the McLeagle, qualifying ninth at Michigan. That weekend he tasted a great Can-Am machine when he raced the spare McLaren M8B to third behind Bruce and Denny, having started from the rear of the grid.

Pete Lyons wrote ‘…from the back…he passed twelve cars on the first lap…Each lap Dan passed fewer cars but he passed them relentlessly. He gave the impression of being careful, feeling out the car, not risking breaking it, yet the big orange gun shot his black helmet along like a cannonball. When he caught Brabham, he went by so fast the two could hardly exchange glances…’Jack knew exactly how Dan felt as Brabham tested the same car during qualifying – and did a time in a limited number of laps good enough for row two of the grid!

In tragic circumstances, after Bruce’s death at Goodwood, Dan raced a works McLaren M8D Chev with great speed and success until sponsorship conflicts intervened and stopped his campaign short. It was a great pity as a Hulme/Gurney battle for the 1970 Can-Am title would have been a beauty. It was a fascinating season in the short history of the series inclusive of the Chaparral 2J Chev ‘Sucker’ machine; to have finally seen Dan in a car truly worthy of him would have been something, albeit not G-W Ford powered…

Into 1970 the AAR USAC machine, the ‘7000’ designed by Len Terry – was both Offenhauser and Ford G-W powered – and achieved its final G-W stock-block win in Swede Savage’s hands at the season ending finale at Phoenix. The 1971 ‘7100’ was designed by Roman Slobodynski and built to suit the Drake Offy turbo-charged four cylinder engine only.

What a marvellous run the Gurney-Weslake small-block Ford V8s had…

Etcetera…

Bibliography…

‘Dan Gurney’s Eagle Racing Cars’ John Zimmerman, ‘Can-Am’ Pete Lyons, gurney-weslake.co.uk, phystutor.tripod.com

Credits…

The Enthusiast Network, Dave Friedman Collection, AAR Archive, Tim Mathiesen

Tailpiece…Dan aboard his second place Eagle Mk4 Ford G-W, Indy 1968…

Finito…