OT: timing belts

From: Jules Richardson <julesrichardsonuk_at_yahoo.co.uk>
Date: Mon Dec 27 06:36:47 2004

On Sat, 2004-12-25 at 09:43 +0000, Gordon JC Pearce wrote:
> Triumph Stag V8s - all notorious for timing chain failures

To be fair there most of the breakages in the old days were down to the
awful quality control at Triumph; they left a lot of silt in the block
as part of the casting process which eventually blocked the oil feeds to
the chains, causing them to overheat and fail.

In more modern times there have been a lot of substandard-quality repro
chains about (you get what you pay for and all that) which are prone to
stretch and break. Know what to look for and it's a solid enough design.

> ), or just allow the chain to
> slop about once it's worn (pretty much every other OHV chain-driven
> engine).

The tensioners should pick up the slack on the 'undriven' side of the
chain so there's no slop, but yep crank-cam timing will alter slightly
as chains and sprockets wear. Good chains don't stretch, they just wear.
IME it can't be more than about a degree out; much more than that and
the wear would be sufficient to induce chain or sprocket failure anyway.

> Of course, the Ford Essex 3 litre V6 in my Scimitar solves the problem
> by having no belts or chains at all - just two big gears. The large
> gear uses fibre teeth which wear after a few hundred thousand miles, but
> that's another story....

That seems like a sensible way of doing it. I take it the Essex is quite
a flat vee design? (just thinking about the Stag engine which is 90
degrees and there's a hell of a distance between crank and cams)

cheers

Jules
Received on Mon Dec 27 2004 - 06:36:47 GMT