On Fri, 05 Jun 2009 23:30:24 +0100, Dave Plowman (News) wrote:
Apart from the simplex chains having a short life...

Yeah, 15k miles IIRC*. Although replacing them was a pretty simple job,
and they weren't *that* expensive an item, so I'm not sure it's any
worse than the maintenance schedule on a lot of modern vehicles. Just
worse than most contemporary ones. :-)

* although maybe I'm thinking of the Lotus Esprit...

Most timing chains have a pretty long life.

Not too familiar with them, TBH - I think my MK1 Escort may have had one,
but it was one car where I never had cause to dismantle the engine :-) My
old truck just has timing gears (which are prone to stripping, it seems)

Cam belts are the things that
need a routine change - but even then I don't know of any where this is
15k miles. Most are three times that or more.

I'm out of touch there - I remember 30k being common for cam belt changes,
but that was on vehicles that would be getting on for 20 years old now
(how time flies!)

I'm not sure why the Stag ones had such a short life - there wasn't
really anything inherently oddball about the design. The hydraulic chain
tensioners were prone to wearing out, though. I suspect it may just have
been that the oil pressure wasn't particularly good on that engine,
even from new, so the engineers hedged their bets and specified a low
replacement interval.

Now there might be merit in making a four cylinder as
short as possible - and including a layshaft that can also be a balance
shaft - but not really a V-8 which needs neither. They could still have
used the basic Dolomite design but fitted a conventional water pump and
a distributor driven off somewhere else. After all the inlet manifold
wasn't common to the fours.

Yeah, I'm not even sure what the basis was of using the Dolomite engine,
unless it was purely a way to get an initial green-light (i.e. they
convinced someone it'd be easy to throw two together and get a V8)

The Stag isn't a particularly wide car though, so maybe they thought there
wasn't the space to have the pump and dizzy off to one side rather than
in the middle.

The prototype was made from a six cylinder car - IIRC an estate. And it
is an easy job to fit that engine.

Sure, but I think it was a marketing thing - they always wanted it to be a
V8, even though the prototype used a six... wish I had some of my
documentation here to confirm that, though!

IIRC, the overheating was caused by a poor rad and waterpump - later
versions were better.

Oil passageways weren't anything special, the oil pump wasn't that good,
and factory quality control was such that a lot of engines shipped with a
boat-load of casting sand still kicking around in the engine - which
promptly found any way it could to clog things up.

IIRC the later cars got a better rad, but I don't recall if they did
anything to improve the water pump now...

cheers

Jules