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Replacement camshaft manufacturers are at great pains to instruct you to run the engine on first start up for 20 minutes at 2500 rpm or thereabouts. Assuming this to be standard protocol how was this sort of procedure accomplished on the original production line - engines run up prior to installation, or was there a group of vehicles at the commissioning stage of the production line all having the nuts revved off them, before dropping the revs, checking the mixture/timing and driven out to park up ?

Just wondering as I've followed this instruction in the past, you make a right racket and don't half get some dirty looks from folks passing by! Err, sorry 'just running in'....

The 'incredible baby seven' pathe video on you tube shows an engine being run up on special running in oil before being mated to a gearbox. This appeared to be standard production procedure for all engines being built.

However, I thought the twenty minutes running was to harden a re-profiled camshaft. I presume a fresh grind received some kind of hardening treatment prior to installation.

A neighbour of our was the foreman of the Engine Shop at our local Zetland factory for 18 years. I do recall him saying they were running the engines for 30 minutes on the engine test stand (as gs has said ^) until about 73 when the oil crisis hit and they reduced this to 20 minutes as their weekly fuel bill was getting rather expensive, though because of what it was being used for they didn't have to pay excise or tax on it (not that it would have been much at that time). Management apparently wanted to reduce it to 6 minutes. Anyway, that was how they did the initial bedding of the rings and 'running in' of the Cam. They did use heated oil so they didn't have to waste time and fuel waiting for the engine to warm up and this help reduce the time needed for the cam running in bit.

Just going back to the need to do this and why it's done is that fresh ground steels don't readily absorb Oil. By running the engine at higher revs it ensures that the Cam is being 'fed' plenty of Oil from the Big Ends. With time and heat the Ground Steel begins to absorb oil.

The video shows the engines being spun via an attachment to the crank front pulley, no sump on. How did they get the oil in? Presume through some temporary connection to the oil pick up hole in the block/sump face?

I only spoke with our neighbor about the Mini Engines. They were complete and 'hot run tested'. Next time I see him, I'll ask him about that test stand, they did at an early time have a similar one at Zetland.

All manufacturers run/ran their engines (ok "rev the nuts off them"...).
This serves 2 purposes:
1. If the engine is going to go 'bang' (say someone forgot to torque a rod bolt, etc) it'll probably do it in the first few minutes of running.
2. On modern vehicles, the run (including taking power measurement) is linked to the engine no/VIN, for future reference with warranty.

For older vehicles, people were expected to run-in a vehicle themselves.
-The exception to this, that I know of, was Lotus/Talbot: they found that they were getting engine warranty problems with the Lotus Sunbeam, so they ran-in all of them before they left the factory...

We had a running-in procedure for the bikes at Triumph, but that didn't stop the Germans: it was a regular occurrence that bikes coming for their 1st service at 1000km (600miles) needed a new rear tyre..... -never had any engine problems though!

I think problems occur when an engine is started and left to idle. It's much better to drive the car, letting it rev if it will happily do it (difficult to tell without experience...), and putting it under load for short periods (full-throttle acceleration) followed by lift-off over-run.
-This puts load on the rings, pistons bearings etc, then the over-run allows oil to be drawn up around bores and on bearing surfaces.

-The worst thing is constant load/speed