Back in the days where truly tiny independent teams were still common in Formula 1, this varied a lot. McLaren tended to rebuild engines after 600 miles – or one weekend, practice and race.
Showing the remarkable evolution of the DFV, Nicholson said: “When it first came out in 1967, we were probably getting 1000 miles out of them. OK, we were running to 10,000rpm then, but they were producing say 420 to 440hp. Now they’re running to 11,000rpm, really, and that extra is not good for them.”
As providers and maintainers of race-worthy engines, Nicholson Ltd’s job primarily was not to measure the wear of each part, but to avoid the results of a crucial breakage.
“Pistons get replaced every 1000 miles,” Nicholson said. “They won’t do two race weekends. If you had a failure because of a piston, which in turn broke the engine – even a secondhand one that cost £4000 – that would have bought you a set of pistons for every race in the season, so it isn’t worth economising here.”
Valves and valve springs, meanwhile, would last two race weekends.
“Crankshafts, with a bit of luck, will run a long time, depending on how they wear,” Nicholson said. “I’ve only seen one or two cranks break in the four to five years I’ve been doing DFVs. They wear on the thrust faces of the webs – the end of the journal where the side of the rod rubs. There are different thoughts on why this happens. The end float on a pair of rods in place is set between six and 12thou, but it’ll increase to 15 or 20thou very quickly – in one run. I think it’s something to do with the nitridising of the crank – it’s too hard, it splinters, and the splinters dig into the con rod, which isn’t particularly hard compared with the crank. Then the con rod works like a little grinding wheel.”
Con rods themselves, Nicholson said, he could never get hold of – although fortunately they didn’t fatigue too quickly. Camshafts, while prone to wear a bit at the lobes, would last an entire season. He'd never seen cam followers break.