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Can't vouch for your daughters Fiat, but my old Allegro was a pushrod engine, and that had a chain to turn the cam.
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My much-loved 1965 Mk 1 Cortina (1500cc pushrod) snapped its timing chain at about 80K back in 1982. No damage, just a bill for about £25 to get a new one fitted at our local garage. Also, I seem to recall that a favorite mod at the time by Mini fans was to fit a duplex chain as the original single chains tended to snap at high revs.
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How about a return to the 8 valve engines where there is a good chance the the valves and pistons don't become intimate upon cam belt failure.
I have seen the results of research where it shows that most people do not rev engines enough for multi valve heads to deliver a worthwhile performance increase.
number_cruncher
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>>I have seen the results of research where it shows that most people do not rev engines enough for multi valve heads to deliver a worthwhile performance increase.>>
Hi Number Cruncher, can you post the source of that data, would make an interesting read? I ask because I have just run side by side an 8v Megane and 16v Astra Ecotec for 3 years or more. I finally got fed up of the Astra as it had no urge below about 4000 rpm and to really make progress needed to be revved up to its max. I grew to hate this engine, as my driving style is much more laid back and relaxed. Moreover, it consistently averaged about 37 mpg, compared to the Megane\'s 44mpg. And to cap it all, spent over £450 on belts, rollers and tensioners while I had it. I\'m extremely cynical of high revving, high power output petrol engines, perhaps that\'s why turbo-diesels are proving so popular with their superior \"driveability\" in the real world.
Baz
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Hi Baz,
I saw the data during an engines course given by Prof. Gordon Lucas at Loughborough University. As far as I know it wasn't widely published because it was work done for Ford.
The experiments were done on an instrumented Granada. The engine speed when people changed up was recorded. The car was lent to members of the public who were not told about the purpose of the test. I think they were asked to report back about how they thought the car drove!
Gordon presented the results as a graph comparing the change up revs and the performance curves of the engine. The engine was good for 6000 rpm, but few people went beyond 3500, and virtually none went above 4500.
It was upsetting data - engine designers, fluid dynamics engineers, and valve train engineers put huge effort into making engines deliver at high speed, and virtually nobody used it! At the time, Gordon wanted to do more tests - he wanted to measure the noise of the engine to see if there was something people heard that made them think they had to change up.
The extra complication of multi-valve engines exists purely to allow the engine to breath better at high engine speeds. They are sportier engines, and there is no benefit to be had out of them unless they are revved.
I understand your point about the relaxed driving style with a diesel. Why in particular are you cynical of high revving, high power output petrol engines?
number_cruncher
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Hi NC
Thanks, interesting stuff! To answer your question, well, I'm "cynical" for exactly the reasons above, ie IMO most people don't drive cars in the real world using peak revs and max power! Driveability, economy and flexibility are far more important. OK, there's always going to be a niche for revvy sporty stuff but mainstream cars don't need the same driving characteristics. So my question is why do manufacturers put so much effort into top end performance when we don't need it, we need low end torque most of the time! It can be done, my 8valve Megane was (is)much quicker on the road than the 16v Astra - and quiter, more economical and more relaxed too!
Baz
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Hi Baz,
If I were to indulge in cynicism, I would say that these multi valve engines allow manufacturers to boast higher power outputs which would sway people whom, beleiving people like Mr Clarkson, think they need the power.
I think that the low end performance of multi valve engines is not necessarily poor - i.e., there isn't a technical reason why it has to be a trade off. I would expect the power and torque curves of similar sized engines to overlay until above 4000 rpm, when the multi valve engine will produce more power and torque.
Taking a slightly different direction, I think the way that engines are controlled at the moment is not optimal. Hopefully, CVTs and similar devices will take the direct control of engine speed away from the driver. So, drivers will press the pedal to demand acceleration, and the powertrain controller will determine the best way for the engine/gearbox to deliver the best response / economy / emmisions.
number_cruncher
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Hi Yes agree with you entirely - my comparisons are merely subjective and of course 2 different makes of engine! It will be interesting to see how technology develops, I imagine you're correct in that engine speed control will be taken away from the driver ultimately. That opens up a whole new area for discussion of course! Thanks for interesting feedback.
Baz
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Modern turbo-diesels still have belts, rollers and tensioners and in a lot of cases 16 valves, plus they have the turbo which isn't exactly unsophisticated and is another point of failure.
However, I would agree that their real world driveability and their economy make petrol cars rather tiresome to drive by comparison.
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These fiat engines are chain driven - the cam has to be driven somehow and the three choices are belt chain or gears - back to the original post - your focus timing belt is due at 100,000 miles or five years whichever is the sooner and on a 1999 car you\'re at or very close to five years old - obviously up to you but I would imagine if Ford were to contribute to any damage then the car would have to be within the specified timeframe/mileage.
good luck
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Hi
Why Does Ford say 100,000 miles or ten years for a 2000 fiesta.
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(iam not a mechanic)
Martin Winters
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Ford says 100k for a fiesta becuase:
1. the belt design is such it is well engineered: look at the auxiliary drive belt as an example (if you have power steering or AC you will see it is very wide and ribbed and a fairly short run)
2. Ford Zetec engines are fairly oiltight.
3. Ford tensioners are of good design.
Contrast that with well known failures: the old Ford 1.8 diesel engine being a classic case, the Land Rover 2 litre diesel of the mid 1990s before BMW, etc.
ALl imo of course..
madf
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Hello.
Thanks for that great reply :)
When would you reccomend changing it as i cant bear to wait that long.
Plus over time rubber deteriorates and the other half mainly does stop start journeys.
--
(iam not a mechanic)
Martin Winters
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Personally I would change at 6 years/60,000 miles - whichever comes sooner.
(Changed SWBO's Peugeot 106 1.4 Diesel at 6 years/25,000 miles. next change due next year at 12 years /47,000 estimated miles..)
madf
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I asked a friend of my son who has been a Ford mechanic for three or four years now about the timing belt on my sons Ford Focus 1.6 zetec, and he said that in his opinion the parameters set by Ford are realistic. He justified his opinion to me by saying that he personally had never seen a 1.6 zetec (I don't suppose that it would make any difference which car it was in)with belt failure in his workshops.
With regard to high revving petrols, I changed from a 2.0 16v Peugot 206 cabriolet to a C3 HDI 92bhp (I've had several n/a diesels and turbo diesels before the 206), for exactly the reasons stated, drivability, economy and the feeling that you aren't ringing the engines neck to get it to go, which I suppose equals noise.
Reggie
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