On Thu, 23 Dec 2010 00:13:04 +0000, Grimly Curmudgeon
wrote:

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Eric Stevens
saying something like:

Of course that was another problem. Then, the Roots group (Humber,
Hillman) couldn't control cylinder bore diameter to better than .010"
so that when choosing pistons, all engines had to be selectively
assembled. Ford had similar problems when machining blocks for
crankshaft bearings. Those, too, had to be selectively assembled and
bearing shells had a 'fit' code which had to match the housing in the
block and the cap (often different). Rover decided to take advantage
of generous tolerances to use Loctite to secure cylinder liners in
place. But they couldn't machine all blocks/liners sufficiently
accurately and liners used to move in the block. On occasion a liner
would drop to the point where the top ring on the piston would snap
out over the top. Things stopped rather suddenly once that happened.

These days I shudder when the British talk of British Craftsmanship.
I'll take Japanese craftmanship any time.

Hah, it goes back further.
An oft-repeated tale, but I actually knew (worked with) a bloke who was
there, in the era.
RR Merlins were made under licence by Packard. Nobody in RR service/tech
departments could believe that Packard's production line could possibly
produce engines to the tolerances needed.
On stripping a couple down they found them to be better...

Originally itwas not Packard but Ford who were to make the Merelin in
the US. They had to go through all the RR drawings and rework them to
tighten the tolerances to render them fit for production line
manufacture. Before they finished this work Packard took over the job
and also had to rework the drawings. The British made Merlins relied
on considerable 'British Craftsmanship' to enable the less precisely
made British Merlins to be assembled.

Btw, the bloke I knew was employed by RR to visit the various front-line
fighter bases and rebuild worn and battle-damaged Merlins. The RAF
mechanics were perfectly capable of doing it, but if he did it, the
factory warranty applied. Strange thought - a factory warranty on a
fighter engine in the heat of battle and I wonder if the RAF ever
claimed it. Probably self-limiting, in that if enemy action caused the
damage, the warranty was void.

Manufacturing and design problems did cause some engine failures and
the loss of aircraft.



Eric Stevens