How long do timing chains last?

[beero]

I am rebuilding a 950 engine that has done about 50 odd thousand miles. I am changing rings, big ends, mains, oil pump and pressure relief valve, water pump and exhaust valves.
The timing chain and gear wheels do not look worn but is it worth renewing the chain and wheels? If so is the duplex worth having and do you need a bigger cover for duplex?

[MarkyB]

This is a little contentious, I favour the duplex because it is simple to fit (just countersink 2 existing holes) and the original cover is used.

Other people will say that the later mini set-up with a chain tensioner is superior in every way, however you do need to drill a blind hole in the front plate and work out where it needs to go and get the mini cover.

I think we would all agree that while you are in there replace the chain with something even if it's simplex again.

[linearaudio]

Frankly, judging by the quality of modern chain, unless you can find a new-old-stock item as I did, you would be better off with the existing one!!
Good chain manufacturers are very rare and VERY expensive. Wippermann or Sedis are about the only guaranteed good makes, the spec number is 06B-1 (duplex is 06B-2). No, Renolds isn't to be relied on any more! I have a 5m box of "Tyco" Tiawanese chain, about 1/5 the price of the above, but I wouldn't put it anywhere near my engine!

[bmcecosse]

Since the small sprocket does twice the work of the large one - minimum replace is new chain + small sprocket + new 'tensioner' rings. Duplex is fine - not rattle proof - and not necessary for a standard engine - but fit if you wish. Same cover is used IF it has the rubber oil seal fitted ?

[beero]

Thanks for all your advice. I will go for a single chain and sprocket set I think.

[bmcecosse]

The larger sprocket is probably relatively unworn. Be sure to fit new tensioner rings though!

[chickenjohn]

Frankly, judging by the quality of modern chain, unless you can find a new-old-stock item as I did, you would be better off with the existing one!!
Good chain manufacturers are very rare and VERY expensive. Wippermann or Sedis are about the only guaranteed good makes, the spec number is 06B-1 (duplex is 06B-2). No, Renolds isn't to be relied on any more! I have a 5m box of "Tyco" Tiawanese chain, about 1/5 the price of the above, but I wouldn't put it anywhere near my engine!

Good information. Just how expensive is "VERY" expensive?

EDIT, quick Google reveals £248 for 5 M Wipperman 06B-1. But you will be able to get a lot of Minor chains out of 5M, that is about 15 foot so would give you (I guess) about 15 simplex timing chains. £248/15= about £16 per chain. I'd pay that for a chain that would last the distance. Maybe if we have someone with the knowledge and tools to make 15 timing chains out of one big length this could be a good idea for a group buy???

[ampwhu]

i've never heard or seen of a timing chain that has ever snapped or broken. sure the rubber's wear out and the chain chatters..... but i've never break. don't forget some of the A series engines are over 50 years now and still on the same chains.

[chickenjohn]

i've never heard or seen of a timing chain that has ever snapped or broken. sure the rubber's wear out and the chain chatters..... but i've never break. don't forget some of the A series engines are over 50 years now and still on the same chains.

That is true, I've never heard of one breaking- unlike cam belts- and as you say " with the original" chain. The concern is if you replace your original chain with a new re-manufactured one in good faith and it turns out to be poor quality and snaps ruining your engine!

[katy]

Which leads me to ask; are the A series an interference engine?

[ampwhu]

i've never heard or seen of a timing chain that has ever snapped or broken. sure the rubber's wear out and the chain chatters..... but i've never break. don't forget some of the A series engines are over 50 years now and still on the same chains.

That is true, I've never heard of one breaking- unlike cam belts- and as you say " with the original" chain. The concern is if you replace your original chain with a new re-manufactured one in good faith and it turns out to be poor quality and snaps ruining your engine!

without doubt. keep the original and just change the rubber rings.

saying this, for my own personal preference.... i've fitted a duplex so that i don't have to replace the rubbers again. it's down to my choice though

[MarkyB]

the A series an interference engine?

No,[generalisation] not many petrol engines are [/generalisation]

I rather doubt there are many original timing chains out there, but anything is possible.
Were the originals Reynolds chain?

[ampwhu]

the A series an interference engine?

No,[generalisation] not many petrol engines are [/generalisation]

I rather doubt there are many original timing chains out there, but anything is possible.
Were the originals Reynolds chain?

my 803 is on its original chain. it has covered 127K and runs as smooth as a swiss watch.

[MarkyB]

To be honest I never considered side valve engines.
How does the timing chain etc. compare to the OHV engine?

It may be that the perceived weakness in the A series timing chain is down to poor maintenance, or the design of the "tensioner"

[bmcecosse]

The SV engine actually had a duplex chain! The very same Simplex Chain and sprockets are used on the B series engine too, I too had never heard of one breaking - until recently (well within last year) I think two cases were reported on here. And yes -certainly on the 1098 std camshaft and the 1275 cams - the valves do go down the bores slightly - so damage is highly likely.

[beero]

I'm worried now about changing when the original may be of better quality than a replacement.
As I can see no apparent wear maybe I will stick with it and if it rattles too much, change it then.

[bmcecosse]

The Mini tensioner system is THE way to go.

[katy]

No,[generalisation] not many petrol engines are [/generalisation]

Suggest you check out this site: http://www.aa1car.com/library/timing_be ... ngines.htm
They list well over 100 interference engines, mostly petrol. (Gasoline as I calls it)

[linearaudio]

I'm worried now about changing when the original may be of better quality than a replacement.
As I can see no apparent wear maybe I will stick with it and if it rattles too much, change it then.

If you are (rightly in my opinion) worried about the junk chain available, then get a NOS one from ebay. thats what I did. Make sure it looks authentic, ie: in an old 60's-70's design package. "popy760" is a good ebay stockist for old bits, I've met him and he breathes old cars, particularly BMC's!

Just found a genuine BL one on ebay! Item no 150459108556. Sorry don't know how to do a link to ebay! This one would do you perfectly!! GET IT!

[bmcecosse]

It's cheap as chips at the moment - but by the time we all bid on it ...........http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 3D1&_rdc=1