J. Lyon
214 posts
Joined: 11/12/2006 18:57:13
Location: Colorado springs United States
Timing Chain
I am thinking of changing out my timing chain and sprockets, it's about time at 109,000 miles. I was wondering if any of you could give me some idea of what style my engine has, the duplex or simplex timing chaing? It's a 1978 Mini 850 with the engine prefix 85H. Thanks in advance!
-James
Posted: Sep 13, 2008 10:32 PM
Batmini
168 posts
Joined: 11/03/2007 10:47:54
Location: Kidderminster United Kingdom (Excluding channel Islands)
As standard it will have a simplex (single row) chain. Also, unlike timing belts, unless there's any damage to the chain, they don't need changing regularly like belts do.
Have a look at the chain and sprockets when you remove them, the first thing normally to wear are the profiles on the gear sprockets. They should have a fairly square profile, not sharp points.
Remember to mark the alignment of the sprockets and shafts before removing to make sure you keep the timing the same when rebuilding !
When refitting the sprockets they should slide on quite easily by hand. DO NOT 'TAP' them on with a mallet. If you hit the crank or cam sprockets on this can damage the oil pump or bearings. Also check for play on the key/keyways on the sprockets, if necessary replace the keys.
Posted: Sep 14, 2008 10:00 AM
Would it be better to keep the simplex chain, or is there some way to convert to a duplex, does it really matter and what's the difference? Thanks for your help!
Posted: Sep 14, 2008 05:53 PM
Tim
1849 posts
Joined: 18/10/2004 09:40:59
Location: Bournemouth United Kingdom (Excluding channel Islands)
Minispares sell a duplex kit - quite cheap and straightforward to fit. The idea is that the duplex chain won't stretch as quickly as the simplex, and whilst stretch isn't fatal it does make the cam timing a bit erratic. The choice is yours, but if you're replacing the chain anyway, which is sensible on a major rebuild, and if the sprockets look worn, which they probably will be, you might as well fit the duplex set.
Posted: Sep 14, 2008 07:20 PM
And what of the belt driven system? Better or just over kill? I'm looking to get my cam timing dead on(or as close to) and quiet down the some of the chatter, which I would assume would be best done by getting rid of the chain. Is the belt worth fitting though? Thanks for the input!
Posted: Sep 15, 2008 01:21 AM
I personally think that unless you're building a racer, then the belt drive is just overkill. Or a bragging point for your mates !
To get the valve timing spot on go for a vernier/adjustable duplex kit.
Posted: Sep 16, 2008 02:49 PM
The vernier gears are a good idea, but you can achieve the same thing by using an offset woodruff key. Minispares do them from 1 degree to 9 degrees. Of course, there's no adjustment, so you have to measure the timing with the standard key, calculate the offset you want, order it from Minispares, and hope when it arrives that it's the right one!
Also, you could maybe fit a timing chain tensioner to minimise the rattle? Not sure if there is such a thing for an 850, but it would surely be possible to adapt one from another engine.
Posted: Sep 16, 2008 03:36 PM
Alright all. Thanks for the input, now I just have to decide on which one to get... Seriously though, were it not for you helpful folk I'd be in the dark with a broken flashlight and a haynes manual...
Posted: Sep 16, 2008 07:55 PM
shaun
10 posts
Joined: 08/12/2008 19:46:48
Location: much wenlock United Kingdom (Excluding channel Islands)
timing chain A plus engine?
on looking for a replacement timing chain for my 1979 mini 1000 i've found that an 11 hole timing cover should mean its an a plus engine, it also has a tensioner.
the engine number matches that in the log book so presuming its origanal.
i always thought a plus engines where a much later thing, fitted to metros
have i got an a plus engine or is it likeley to be standard?
engine number is 99h792ph024897
thanks
Shaun
Posted: Dec 31, 2008 07:41 PM
timing chain
so does that mean that this is an a plus engine or is it an origianal?
i've took the timing cover off and it has a simplex chain and a tensioner fitted, is this standard even on normal a series engines?
thanks for info
Posted: Jan 01, 2009 06:21 PM
heres a picture of the timing gear in situ if it helps anyone
Posted: Jan 01, 2009 10:32 PM
Stoves
4 posts
Joined: 25/10/2011 20:23:44
Location: Grimsby United Kingdom (Excluding channel Islands)
Is it possible to change the timing chain with the engine still in the car.
Posted: Nov 06, 2011 08:46 PM
Yes.
Set No.1 piston to TDC.
Remove radiator (if side mounted) then fan belt, lower pulley and timing gear cover.
Now you can remove timing chain and gears and replace chain.
When refitting cover, put on loosely, fit pulley then tighten cover screws (this helps centre timing seal to pulley and reduce likelyhood of leaks.
Posted: Nov 13, 2011 11:16 AM
paslow22
24 posts
Joined: 03/12/2012 07:18:14
Location: Hamlyn Terrace NSW Australia
What timing chain?
Hi.
I have a 1998 1275 spi x Japan standard specs, and I have been told has a simplex t/chain, I was thinking of changing it to a duplex as it is starting to leak, and as mentioned on another site stated that you can fit a tensioner to stop rattle.
I have also read that if a tensioner is fitted to duplex it may break.( I read a lot)
Anyone have any experience with this combination.
Which way to go, it's not raced or driven hard maybe just to replace it with quality simplex.
Problem solved.
But If the motor should give up the ghost I will do it up to a 1330 or 1380 maybe?
Anyway let me know, thanks
Posted: Feb 26, 2014 05:32 AM
Changing timing chain in car
1998 Rover 1275 x japan now residing in Aystralia
I am about to change my timing cover seal also changing my simplex chain to a duplex chain and fitting a new water pump while I'm at it.
What I would like to know are the difficulties with doing it in the car.
Any information would be helpful.
Thanks
Darryl
Posted: Sep 23, 2014 10:44 AM
I've changed the clutch with the engine still in the car, and changed the water pump, but never tried the timing cover. I can't think of a reason why it can't be done.
Posted: Sep 23, 2014 02:58 PM
I'm going to give it a try.
Posted: Sep 24, 2014 04:52 AM
Sam Castro
1 posts
Joined: 02/11/2017 22:03:40
Location: Hasselt Belgium
Timing belt vs timing chain
A couple of years ago I recieved a disassembled 1380 cc engine from a friend. My dad and I are now trying to reassemble it. We noticed that the timing chain had been replaced with a timing belt kit. We are wondering if ther is any advantage or disadvantage of using the timing belt?Or is it more sensible to convert it back to a timing chain?
Thank you in advance,
Sam Castro.
Posted: Jun 07, 2020 06:08 PM
Martin
17 posts
Joined: 09/10/2008 13:41:13
Location: Heathfield United Kingdom (Excluding channel Islands)
'95 Rover Mini Cooper...SPI...Air filter? oh and timing chain?
Hi All,
New to the site and classic mini's. I am off to pick up my g/f's new car at the weekend...a '95 1275 cooper. I am juststarting to learn the specific details of the cars, and one in particular has eluded me so far...
Basically it has a stainless sports exhaust fitted, but my g/f wants that bit more noise from an air filter, however I am unsure which to buy as there are seemingly hundreds of options for the old carbs and SPI mini's...some say one type of K & N will fit, others not e.t.c e.t.c. Can someone finally advise which filter will fit (Green filters sell one for up to a '92 1275 cooper?).
Lastly, I'm used to timing belts and the annoyances that they cause...I'm 90% certain that the mini is a timing chain, can someone clarify this?
Cheers!
Posted: Oct 09, 2008 01:56 PM
J. Clarke
1948 posts
Joined: 28/05/2006 16:49:46
Location: cambridge United Kingdom (Excluding channel Islands)
http://www.minispares.com/Product.aspx?pid=35337
this is what your after, other choice is replacement K&N element in standard airbox, but that wouldnt be noicyier.
yes they use a timming chain, mini engines are pushrod so cam is at back of engine near crank so timming chain is short. rods push rockers that push open valves.
rember exhaust and airfilter will need decaring as mods for insurance or the policy is invalid and so in crash it would be u paying for damage and injory compensation.
Posted: Oct 09, 2008 10:57 PM