Unlike these cars though, the engine was designed to be a stressed member of the chassis in the same configuration that the much more successful Cosworth DFV would later establish as the norm, and was mated to a 6-speed gearbox, with the gear lever unusually situated to the left of the driver.

The rear suspension consisted of twin radius arms, reversed lower wishbones, single top links and outboard springs and dampers, attached to the gearbox and engine.

At Monza the team had problems all weekend, with even the P261's engine failing at one stage, and in the race Hill's H16 blew on lap one while Stewart had to retire when a leaking fuel tank left him soaked in petrol.

Hill suffered gearbox problems early on in the race but managed to carry on, while with other cars retiring Stewart found himself in third place by lap 35, a fair way behind Clark's Lotus in second.

On the following lap the leader Brabham broke a camshaft, allowing Clark to nurse his car home for an incredible first (and it turned out, only) win for the BRM H16 engine.

He qualified twelfth on the sixteen-car grid and scored the P83's first points with sixth place in the race, although he was the last car to finish and fully 4 laps behind Denny Hulme's Brabham.

Stewart himself was then overtaken by winner Dan Gurney after his car developed a gearbox problem, having to be driven single-handed while the other hand held the gear lever in place.

Nevertheless, Stewart brought the car home in second more than half a minute ahead of Chris Amon, while Spence scored points again finishing a lap down in fifth place.

In the race Spence completed nine laps before a halfshaft broke, while Irwin was running fourth when an engine problem put him out, although he was still classified in fifth place.

At Silverstone both of the works P83s suffered suspension failures in practice, and as a result Stewart took over the Reg Parnell P83 of Irwin, who in turn was given the P261 of Piers Courage, who had to sit out the race.

BRM built a new lightweight P115 chassis which arrived for the German Grand Prix, and Stewart would use this car for the rest of the season leaving Spence and Irwin in the heavier P83s.

Fuel injection problems forced Irwin out after 16 laps while running tenth, Spence doing his usual job of hanging around and taking advantage of retirements to finish fifth again.

Irwin moved up to twelfth before his engine ran out of oil, while Spence, as so many times in 1967, managed to hang around until the end to claim fifth and two extra points.

Like Graham Hill the year before, Stewart decided to leave BRM for 1968, joining Ken Tyrrell's new team, while Spence was killed at Indianapolis in May 1968 and Irwin's career was cut short by a sports car crash at the Nürburgring less than two weeks later.

[8] Chassis 8303 was fitted with a 3.5 litre Rover V8 and made a one-off appearance in the hands of Peter Gerrish at Hockenheim in 1971 but retired, again due to engine failure.