Timing chain tensioner

[fweddy]

I have my timing chain off at the moment.

I was talking to an old BMC mechanic and he mentioned the early A series had a tensioner in the cam gear. later ones had an arm type tensioner. but some in the middle had none. Mine has nothing.

He recommends I get an older type to add some tension - what do you know abou this? What years did it change?

I've just spent this evening pulling a '68 1098 timing cover off and it appears the same as mine. What has the austin 1000 engine got? How about a 1977 mini 1000?.

Thanks

[Cam]

You don't really NEED a tensioner. I don't have one either.

How did this early 'cam-gear' one operate then?

[Kevin]

If you want to improve it so that it stays quieter longer go for a duplex conversion.

[57traveller]

I was talking to an old BMC mechanic and he mentioned the early A series had a tensioner in the cam gear.

I would presume he means the two flat rubber rings that fit onto the gear wheel (sprocket), slightly smaller diameter than the root of the teeth.
I've a set somewhere and can post a picture if required.

[Cam]

I've a set somewhere and can post a picture if required.

Yes, just out of interest if you don't mind.

[57traveller]

They're also shown in the Haynes manual - page 27, engine running gear, item no. 64 x 2 fitted each side of the camshaft sprocket.

[57traveller]

Two tensioning rings are already fitted into deep slots in the sprocket shown marked by arrows. Spares in packets on left.

[fweddy]

If you want to improve it so that it stays quieter longer go for a duplex conversion.

Don't I loose the hand crank then?

I would presume he means the two flat rubber rings that fit onto the gear wheel (sprocket), slightly smaller diameter than the root of the teeth.

Yep - that sounds exactly like what he was talking about. How deep are the slots?, The cam gear I pulled off the '68 was slightly different to my '73, maybe it was the one that was ment to have the rings.


How would I be if I just replaced the chain and not the gear wheels. The cam one is still ok according the the Haynes manual. (the teeth are not concave on one side compared to the other.) but they do have tiny 'pitting' where the chain rubs (ie wearing thu a bit).

[Willie]

The two rubber rings are the standard fitment for the Minor engine,
not very efficient for long which is why the Minors rattle a lot!.
The Metros used a spring loaded tensioner which is pretty easy
to fit and does the job but involves changing the timing chain cover
too and then you have to reposition the timing marks. By far the
easiest way is to fit the Duplex chain kit, under £30 and the only
tricky bit is to replace the two bottom nuts with countersunk screws
so as to avoid hitting the duplex chain. NO, you will not lose the
starting handle facility.

[bmcecosse]

Duplex is best by far - especially if you are fitting a better camshaft - which you should ! Not only do you need to fit c/sunk head screws, but also watch which way you fit the chain. One side has two pins sticking out slightly further than the rest (the joining link) and so these need to be pointing outwards away from the c/sunk scres. MG Metro cam is the one to get - about £10 on ebay usually. Great improvement in the engine - you will also need a peg drive oil pump - but they are better anyway !

[bmcecosse]

To get back to the original point - I have never seen a timing cahin with NO tensioner (except duplex) it would be very noisey !!

[fweddy]

MG Metro

hmm now where would I find one of those in New Zealand? - Think I saw one once.

[57traveller]

Yep - that sounds exactly like what he was talking about. How deep are the slots?

fweddy - the smart a____e answer is deep enough to accomodate the rings!

The rings, I'll use metric, are approx. 4mm thick and approx. 12mm wide (ie. 106mm o/d x 82mm i/d). The outer edge protrudes very slightly from the slot and the chain contacts this edge when it's all new. Can't see this method being very efficient personally, however, I fitted new chain, gears and "tensioners" about 20000 miles ago to my saloon and it's not rattling yet? Decided against a duplex arrangement because I didn't want to start drilling countersinks in the plate to fit the replacement front securing screws which locate in the main bearing cap.

[fweddy]

Thanks - I've pulled another timing cover off and discovered a gear with that rubber ring setup. Problem is the rings are worn down further than the lip that holds them on and the teeth on the gear are pretty worn too. I've got my new timing chain and tried it on my existing gear and its pretty tight (a very slight sag) but heaps better than my original - I think I'm going to go with it like that. I also don't really fancy the time and hastle of fitting duplex, especialy as I'll have to get it from an east/west engine and hence loose my hand crank.

I was hoping to get my ute runnig for Sunday morning for a classis car rally but I realised that while its been sitting in the shed under repair the WOF has expired (read MOT). It hardly seems like six months since I got it on the road!!

[bmcecosse]

No you still keep the hand crank - and you can fit the crankshaft damper from the E-W engine too, which smoothes the whole engine and helps to preserve the timing chain - and the crank if you drive it hard !!

[newagetraveller]

If the original tensioners are worn and you do not have any new tensioners or a duplex timing chain but wish to solve the problem proceed as follows:
Place large toothed wheel in a saucepan and cover with water.
Place saucepan on a cooker and heat it up. This will soften the tensioners.
Take toothed wheel out of saucepan and carefully extract tensioners usind pliers and a small screwdriver or similar. Take care not to damage the wheel here.
Use a cloth to clean tensioners and groove in wheel where they fit.
Wrap several turns of PTFE tape in each groove and replace tensioners.
Tensioners should be standing out further than before now. (Trial and error here)
Too much tape -> tensioners stand out too far and chain will be too tight.
Too little tape -> tensioners do not stand out far enough.
Replace wheel and chain.