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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - New Timing Chain

Putting a 20,000 mile engine back together, would you always get a new timing chain? I can't see anything wrong with the one that came off, and the slack is exactly like that shown in Haynes.

It's only £3.95 from AH Spares, which is worryingly cheap, and I also wonder whether it's good practice to get the whole set rather than add new to old.

BTW, the cam shaft sprocket seems to be much fatter than I remember - you can't lay a straight edge across the two sprocket faces - and with some sort of sandwich construction. Has anyone else got this?
Nick and Cherry Scoop

In your shoes I would change it for the Vernier style, just so you can make adjustments latterly if need be.
Is it the sprocket or cog on the crank that gets shimmed to take care of this . . others with more knowledge than I will be along to say on this.
P Bentley

As you say, worryingly cheap.

Personally, I'd leave it.

Vernier timing gears are OK if you're constantly changing the cam timing to optimise it, but if you are going to time it once and leave it, an offset woodruff key will do the job, if it's far enough out to worry about.

Shims go behind the crankshaft gear.
Dave O'Neill 2

Thanks Dave. I think I will put it back in. It's 1981 vintage, which may be a better quality than the £3.95 new one.
Nick and Cherry Scoop

Nick

For engine parts I use Minispares. I would use a new chain if not the full set. You can also get offset keyways from Minispares for when you set up your camshaft.
You should probably replace the triangular cam plate to ensure the correct camshaft end float - ensure that you fit it the correct way around.

Alan
Alan Anstead

Im in the middle on the fence

At 20,000 miles, and as cheap as the parts are

Provided im not living on food stamps ... then id change ojt the old for all new, esp for as cheap as the parts are. You can spare box them or sell on ebay buf your 20,000 miles ahead of the game on a repair that will take you easy 3 days start to complete

Id also do rhe viner sproket just for the purpose of easy living, perfection, and time saving.... you stick it on with the chain, you rotate it into the correct postion, you tighten it down with an allen wrench your done in an hour if you have privious experiance with the old fashioned woodruf keys ad all the fun that goes with that... this project is already labor instinsive and time consuming involved project... this will shave off a few hours of extra head scratching and creating new colorful expletives

If you do go the viner sprocet rhen add alot of extra value to it for really cheap time... use a large hole saw drill and cut out a large ring out of rhe timing cover over the sprocket then cut out another piece of ally aluminum with some good gasket material and ither rivit it back togarher or self tqpers screws then rwpaint it and bolt the modified timing cover back into place.... this way you only have to take the screwa out of the new modified plate on the timing cover to acesss the viner sprocket instead of tearing the entire front off engine to acess the viner sprocket... like 5 min tops instead of 3 days to adjust the sprocket...huge selling point if you sell the car at somepoint
1 Paper

I have to say, it's never taken me three days to time a camshaft, even with those old fashioned woodruff keys. ;o)
Dave O'Neill 2

£3.95 for a new chain? Deduct the retailer's profit margin, the warehousing costs, the packaging, the financing costs, the transport cost around the world by land and sea from the factory (in China). Deduct the (miniscule) labour costs.

So what are you left with? What is the actual cost of materials and manufacture - 30p? 20p? 15p? So what sort of steel is this thing made from?
GuyW

A standard timing chain should be good for maybe 80,000 miles. How long will it take you to put another 60k on it?

We all know that 'new' doesn't necessarily mean good.
Dave O'Neill 2

Nick

I've only just noticed the second part of your query.

I'm guessing that the 'sandwich construction' you refer to is probably the rubber tensioning rings on the camshaft sprocket.

I'm not sure why you can't put a straight edge across them. You should be laying it across the teeth with the chain removed.
Dave O'Neill 2

I too have always gotten 80,000 miles out of a timing chain before the rattle starts. The newer chains have been longer and quieter than the original was. Always change the sprockets with the new chain as the teeth stretch.
Glenn Mallory

Guy: << So what sort of steel is this thing made from >>
that'll be the same sort of steel as cheddar cheese is made from..on a warm day.
There is a big difference between "cheap" [i.e tawdry] and "good value"..
as always buy quality
David Cox

My point exactly David. I just wouldn't trust a £3.95 timing chain. It could be far too expensive!
GuyW

Has anyone used aseriesspares? Their duplex set (which they use on 948 engines) is £75.90. Should I call that reassuringly expensive? An AH Spares single chain set is about £30, and £28 for a duplex set.

David, I didn't know you should lay the straight edge across the teeth: I seem to remember being able to lay it across the faces of the sprockets. In any case, with the damper rings on the cam sprocket there's not much in the way of teeth showing.

P Bentley - I thought about your suggestion, and looked at what's available, but I don't think very precise timing will make a heap of difference. My engine is a +0.030 standard 948cc (994 with the overbore) with a fast road head, 266 cam and standard H1 twin carbs. I can see that if the chain has stretched a little the cam will be a touch late, but how much loss of performance will I suffer?
Nick and Cherry Scoop

" I seem to remember being able to lay it across the faces of the sprockets"

That is certainly the case with duplex gears, as the teeth are right to the edge of the gear face and there are no tensioner rings.

If changing to duplex, don't forget to countersink the two bottom front-plate holes and fit c/s screws.


Dave O'Neill 2

Dave.

Haha... 3 days to time a camshaft, well you have to drink alot of hot tea to accomplish that kind of feat


What i should have referanced was the amount of work and time involved to tesr the front of the engine off to get to the timming chain and sprockets. And then to reinstall and get it set p and runnimg agian

Its not exactly like changing the front wheel

Prop
1 Paper

Ah yes, I see Dave. Thanks. As it happens, I've not worked on a 948 before, only on 1275s (and only two of them). I noted that the aseriesspares kit includes two countersunk screws, and wondered what they were for. I haven't got a countersink bit for steel.

Prop - what are you doing awake at this time?
Nick and Cherry Scoop

I cant sleep...my brain wont shut down, to much sugar i guess

To counter sink those 2 screws holes... i juet used a large drill bit something like 1/2 to 3/4 inch... you dont want to drill deep just enough to counter sink the hole so the screw can mesh flat...just be slow about it and check it often

Prop
1 Paper

Another option would be to keep your sprockets and search out some good chain from an industrial supply joint
It's a normal 1/2" pitch chain and you should be able to get some excellent chain like Reynolds or Sugino off the roll somewhere and either a joining link to suit or join it up with an ordinary link and peen the ends of the pins
Just an option-----wallet friendly
willy
William Revit

Hey willy

If you got an extra volt gauge layimg around you could .... well know


Haha
1 Paper

Would be a good idea to check that the sprocket teeth are not hooked, if they are changing the chain alone is pointless.
David k Brenchley

Well it didnt take me the three days forcast to time in the camshaft on this 1275 unless you factor in the time waiting for the 4 degree offset key to arrive by post. It took me no more than an hour this morning.
This engine has a new cross drilled Billet A.C.Dodd road torque cam.
The gears were seemingly O.K. So it just had a new duplex chain
This half engine is destined for a Kent MASC member's Frogeye
Alan


Alan Anstead

Timing marks on the top, Alan?
And, where did you get the paint?
Nick and Cherry Scoop

Nick
Well spotted. A small plate was made up, which I welded on, so that the timing marks can be relocated after final painting by the owner. I don't know whose paint he uses but I would guess at Moss as I have a rattle can of the same colour in my shed.
Alan
Alan Anstead

I will certainly transfer the marks to the top, Alan, but I was thinking of using paint!

I have just today received news that HMRC will not, after all, require a 31 July payment from me. So I am considering several expensive options.
Nick and Cherry Scoop

Nick: just make up a narrow pointer out of a bit of tin with a point at one end and bend the other end so it can be drilled and held in place with a timing cover bolt. It needs to overhand the pulley inorder to be able to see it easily with a timing light. You can mark the pulley itself with +10 and +20 deg marks (I think you will find that 10 deg equates to 10mm on the circumference).

If you replace the sprockets with the chain you may well find that camshaft end float has been screwed up because the length of step on the boss isn't correct. Wear on the triangular plate won't help but replacing the plate won't solve the problem if the boss is wrong.
Graeme Williams

Nick,

You said, "... but I don't think very precise timing will make a heap of difference. My engine is a +0.030 standard 948cc (994 with the overbore) with a fast road head, 266 cam and ..."

I am not sure what you are planning if you do a NOT very precise timing setting. Are you thinking of just lining up the dots on the sprockets? Since you do not have a stock cam anymore, the cam timing will likely be way off if you just line up the dots.

In my opinion you need to check the cam timing and then either use the vernier wheel or an offset key to set the timing. You could get lucky with lining up the dots, but check to see if it is right, or you may be leaving a lot of performance on the table.

I bought an MGB with a fresh rebuild and a custom cam that had not been properly timed. It only had 105 psi cranking compression because of the bad cam timing. I had no specs for the cam to set it properly, but took a guess and moved it, which resulted in 145 psi.

Charley
C R Huff

I sometimes think it's better to remain ignorant.

1. How do chains fail? Do they break, prompting an intimate conversation between valves and pistons?

2. Is a duplex less likely to do that? Might be a better product, given that there must be greater demand.

3. Where do you get the set from? Alan likes Minispares - any other recommendations?

4. Willy - I'm not enough of an engineer to make my own chain and sleep at night. I love the notion that you'd do it, though.

5. Graeme, thanks; I'll go down and have a look after breakfast, to remind myself what you mean!

6. Thank you, Charley. I will read the instructions and see if I think I'm capable of adjusting the cam timimg. Yes, I was just planning to line the marks up.

Nick and Cherry Scoop

Nick

Minispares is a good place to start for bits http://www.minispares.com/search/classic/Camshaft.aspx

NB can get a standard duplex as well as a vernier one.

Also note that Piper Cams sell duplex chains and vernier kits: http://www.pipercams.co.uk/pipercams/www/product_browse.php?type=&manufacturer=4

Bill Richards Racing are selling Piper Venier duplex timing chain kits: https://www.billrichardsracing.com/for_sale/items-from-the-workshop

Also see what Peter May Engineering is offering: https://www.petermayengineering.com/catalogue7.htm#catalogue7

Cheers
Mike
M Wood

Nick

You really need a DTI gauge to set cam timing, and a degree wheel.

Here's a gauge...

http://www.ebay.co.uk/itm/0-10mm-Dial-Test-Indicator-DTI-Gauge-Magnetic-Base-Stand-Clock-Gauge-/182469796644
Dave O'Neill 2

Nick
This is what you have to do. (See pic)
Alan


Alan Anstead

Never done it on a 950 but on both my 1300's I've gone for the A Plus tensioner. One has duplex and the other the standard single chain. Together with electronic ignition spark scatter is virtually eliminated and there is also the elimination in chain chatter - something even new(single)chains will tend to develop after a few thousand miles.
f pollock

OK, thanks Dave. I've bought the gauge. I will make the degree wheel.

Now all I need to do is discover the method. I remember years ago when I painted a TDC timing mark on the top of the cover using a borrowed dial gauge down No.1 plughole, there was a sort of flat spot at the top of the stroke, making it dificult to identify exact TDC.

I see Alan has gone down the No.1 inlet pushrod hole. Is that better?

Graeme, I see what you mean about the step in the boss. Is it really likely that it will be wrong?

Mike, thanks for the excellent contacts.

Fergus - do you remember where you bought them?
Nick and Cherry Scoop

Rather than try and find TDC with the DTI it's easier to measure a point either side with the same drop and then work out the TDC point in the middle.
David Billington

You need to establish TDC first, then use no 1 inlet to check the timing.

There's probably a write-up in the archives somewhere. If not, a quick search on the Interweb should produce some instructions.

Edit: here's a YouTube video. I haven't watched it, so don't know how good it is

http://m.youtube.com/watch?v=khxDPgEbbAo
Dave O'Neill 2

One came on the Ital engine already bought,the one with the Duplex I bought all new parts from Minispares - except for the front plate and cover, which were sourced 2nd hand off EBay.
f pollock

Thanks, Dave. I got 3 minutes into it and he was still tightening bolts, but it's a nice clear film, and I'm sure he'll get there.

Interestingly, it's a 1275 but he's using single row sprockets. And no tensioner rings.

I don't think I'm watching the one you meant.

https://www.youtube.com/watch?v=rad7cdJmT6k
Nick and Cherry Scoop

No, my link didn't seem to work, for some reason.

Try again...

http://www.youtube.com/watch?v=khxDPgEbbAo


EDIT: No, still not working.

Put this into the youtube search box...

HOW TO SET CAMSHAFT TIMING ON A 1380 MINI A SERIES
Dave O'Neill 2

I've never heard of an A series timing chain failing but I know from experience that using a high lift cam with a simplex chain, not recommended I know, can lead to the rollers breaking up. When I pulled the engine and drained the sump it had lots of little semi circular bits in the bottom which amounted to about 1/3 of the rollers having broken up, engine still ran OK.
David Billington

Dont use thepiston as a DTI measuring point, its most likely dished andwont provide a flat spot to neasure off of.... youe the 1st intake valve aka the 1st valve

And never rock the engine back and forth as it makes the chain resettle back into the gap

Always move the in one way rotation only

If the engine is out then hand rotate using the flywheel, if the engine is not out id use a combo of starter and and fine tune with a larger rachet

To remote the starterjust remove the white /red wire off the selinoid then jumper wire one lead off of the post that held the white/ red wire and a wire from the postive battery side, touch the 2 wires together and she will spin


I love willys idea of getting high quality timing chain by the foot, just take the old chain in to match up....because its by the foot they will need to need to break it so they will easily have the tool to reattach it to make it a circle...just do it right there... no need to buy extra tools

Prop
1 Paper

I'd ignore Props last comment as he obviously doesn't know what he's talking about. No point in trying to determine TDC from the cam when you're trying to check the cam timing. Dished pistons or not won't effect the measurement unless you move the contact point, you need to determine the TDC point from the piston as that's what your using as the reference for checking the cam timing.
David Billington

Its actually very easy to fix TDC with a home-made probe through a plug hole. Just a length of stiff welding rod will do it if you take a measurement both before and after TDC and interpolate the exact point.Set the wire up with a bent over top to form a pointer to read off against a piece of marked card. You don't need to take a measurement as such, just match the points on the up and down strokes of the piston, reading off the positions on your 360degree disc. Then turn the crank to the mid point on the disc to give you the accurate TDC position.
GuyW

David
Your comment probably speaks for many.
Alan
Alan Anstead

David,

Im not sure how im wrong... was everything i said in my comment to be discounted as incorrect ??


Or was my comment about using the #1 valve as a dti ledge instead of using the dti on a dished piston top to be judged wrong, incorrect and invalid as that was the only point you eluded to.


Prop








1 Paper

David
I've seen chains broken up as you describe on our local production V8s with little bits of roller jammed in everywhere
That is where my comment came from as far as getting a good quality chain
Some chains have a joint in the little pin rollers that you can actually see with the naked eye--they must be rolled around at manufacture and then hardened-there is no actual physical joint-----------scarey
A good quality chain has full circle rollers with no joint and won't break up in that way

willy

William Revit

David - thank you: now we're getting down to it. I'm going down the duplex route, which is a pain in terms of dismantling to countersink the two screw holes, but seems sensible for the camshaft I'm using.

Willy - I shall be examining my old chain later, with a strong light and a magnifying glass.
Nick and Cherry Scoop

David mentioned high lift earlier. Does anybody know how high a lift I will get with a Piper K266 cam rather than a standard 948 one?

Prop, I believe the objection was that if you use the camshaft to ascertain TDC, then timing the cam to TDC will be self-referential, or a circular argument, or something. Scientists will have a word for it.
Nick and Cherry Scoop

" Scientists will have a word for it. " - pointless.

"Does anybody know how high a lift I will get with a Piper K266 cam rather than a standard 948 one?"

Unfortunately not. Piper's website doesn't list a K266. I would hazard a guess that it will lift more than standard, but as it is a fairly mild cam, it won't be a lot more.

For the cams they do list, they give valve lift figures rather than cam lift, although this will obviously be dependent on which rockers you have - standard 948, standard 1275, or 'other'.
Dave O'Neill 2

Nick

Are you sure it's a Piper, not a Kent?

Here are the figures for Kent's 266 - in mm, of course!

http://www.kentcams.com/product-details/240/Camshaft/Camshaft/MD266-Fast-Road/
Dave O'Neill 2

It is a Piper, Dave (see picture).

You're right about the valve lift - barely more than standard. The durations are longer though - by 30 degrees on inlet, 20 degrees on exhaust.

Thanks for that. So without high lift, I could reconsider the single chain. AAaargh!


Nick and Cherry Scoop

So it is.

As it has the prefix 'K', it may be a Kent profile.

Curiously, the MGA and early MGB use the same duplex chain as the 1275 A-series, whereas later MGBs - with the 18V engine - use the same single-row chain as the early A-series.
Dave O'Neill 2

Piper grind the profiles should you request them.
The 266 is very sweet, works nicely in 1275 versions especially with high lift rockers.
Peter
Peter Burgess Tuning

Glad you've turned up, Peter. You did my cylinder head and provided the cam in summer 2014 (I am so ashamed of my slow progress). Would you stick with a single row set?

More importantly, where should I buy the new set?
Nick and Cherry Scoop

Hi Nick, I can remember supplying the cam and the head work. No need to apologise over work speed. The longest we have waited is....a customer had a B engine for 10 years before first fire up. I decided I would give generous goodwill but engine was as sweet as a nut :)
I think I would swap to duplex kit as 'the right thing to do'. Mini Spares as supplier? I must add though, we ran a std race B 100 bhp at the wheels, with the regs obtaining at that time, for a hard season on a simplex chain and noted no stretch at the end of the year. We always use duplex setup on A and B as a matter of course.

ps I reckon those are my thumb prints on the cam label :)

Peter
Peter Burgess Tuning

Nick:
Comment about the step on the boss of the cam sprocket you referred back - the endfloat on the cam is set quite precisely. You can check it with your dial gauge. If the triangular plate wears the endfloat will increase and if you change the sprocket it may well be out.

I can let you have an accurate drawing of a timing protractor which just fits on to an A4 size card (print on paper and stick it on to the card). The larger the size, the easier it is to read accurately. It's an AutoCad pdf file than can be emailed.

For a road engine I personally can't see any need for a vernier adjustment for the cam timing. Quite an expense and once set you are unlikely to change it again. Use an offset key as Alan suggests.




Graeme Williams

Good advice Graeme. I have found all the verniers I have fitted have excessive endfloat in the region 12-20 thou which takes a lot of removing metal on the cam sprocket and appropriate crank sprocket shimming! I only fit the verniers on race engines. Offset keys are the best bet I recon in terms of price and reliability. We find 7 out of 10 of the billet Piper cams do not need a change in timing from the 'on the dots' position.
If you fancy 'donating' the drawing of the protractor I can make it available via my website with appropriate acknowledgement to your good self.

Peter
Peter Burgess Tuning

I missed the last two posts. Very interesting. I've now ordered my dial gauge and timing set, and can't wait to start. Graeme, that's very kind of you, but I made a protractor years ago (never used it) in AutoCAD. It would be interesting to compare them. This is what mine looks like, but what I wonder is what diameter hole to cut (hence the many circles).

It's the countersinking I don't fancy. I'm just waiting for the screws to arrive, so that I can try butchering one of my bits to the right angle. Alan Anstead has been giving me helpful advice, but I still don't back my skills against possible disaster.



Nick and Cherry Scoop

Nick,

If you're going to do the countersinking yourself then check you have the right countersink angle as IIRC UNF/UNC are 82 degrees and metric 90 degrees.
David Billington

http://www.blocklayer.com/degree-wheel.aspx
W Dunsmore

I just used a wood countersink bit and it worked fine. Oversize drill bits especially if you modify the angle, will tend to chew the taper.
f pollock

Funnily enough, I think that's what I used, too.
Dave O'Neill 2

Ha! That was my instinct too. At least, to try it carefully. I've found a substantial bit of steel in the shed, to practise on.
Nick and Cherry Scoop

You'll find a new countersink bit will cut very easily. Suggest you then degrease all threads with a cotton bud and thinners, before adding a blob of Loctite when you tighten up the allen screws.
f pollock

Thanks very much. I've never used Loctite. Is it readily available?
Nick and Cherry Scoop

Nick
Mounting your protractor--
If you have the flywheel on--you can centre the protractor up on the flywheel and stick it on with some nice wide,clear sticky tape
With it on that end it's out of the way and you don't have to disturb it to do timing adjustments to the camshaft like you would have to do with it mounted up front
works for me
I printed mine and laminated it--had it for years
I used to have a nice big brass SjgErson one but the last fella that borrowed it decided he needed it more than I do--I like my laminated paper one now instead-----------not
willy
William Revit

Get some off EBay, and if you are assembling the engine get a tube of Wellseal. With careful assembly you can pretty much eliminate any leaks from the rear scroll area.
f pollock

You can get a plastic protrator at most auto parts stores for under $10

My swiftune camshaft came with a freebe and worked great
1 Paper

Nick,

If you are going for standard duplex without vernier you can get offset Woodruff keys from: http://www.minispares.com/

Out of interest - what timing chain cover fits the non-vernier duplex chain when fitting this to 948cc, 1098cc and 1275cc midget engines?

Cheers
Mike
M Wood

Thanks for the warning, David. The screws have just arrived, and are 90 degrees, thank goodness.

Off out again now, but I will digest all this in the morning along with my marmalade.
Nick and Cherry Scoop

Nick,

What thread are the screws as I thought those screws were 1/4" UNF which should be an 82 degree angle.
David Billington

"Out of interest - what timing chain cover fits the non-vernier duplex chain when fitting this to 948cc, 1098cc and 1275cc Midget engines?"

The 'standard' duplex will fit inside any timing cover.
Dave O'Neill 2

David, I haven't got a thread pitch measurer, but the new screw thread sits snugly into the old bolt thread. Simply measuring along the threads, I get 11 per cm, or 28 per inch, as near as dammit: maybe a shade under.

Fergus - is it just normal Loctite - superglue?

Willy - good idea. But where I've got the engine, I can't walk round it, so I reckon I will do it all from the front. Sorry about your prize protractor.

Thanks again, Mike. Though I still find it hard to believe that maximum lift at, say, 108 degrees rather than 106 will affect performance. I like precision, but on a total valve opening of nearly 3/4 of a turn, does it really matter?

Nick and Cherry Scoop

You want Loctite 242, designed for threads.
f pollock

I like the idea of the protractor on the flywheel. THe only problem I can envisage is the fact that the rotation with be clockwise and one would have to be very careful about which side was "before" and "after" tdc.
Graeme Williams

Graeme
You'll like this then-----------
Drove out 100klm to a mate's place to time his MGA engine the other day and forgot to take my timing wheel, and ended up using the ringgear on the flywheel- It was 120 teeth so 3deg. /tooth--worked out good
If I'd gone back for it that would have cut into sitting and laughing time and that's not on
willy
William Revit

Ha ha, Willy! It sounds like now that its running sweetly, your mate needs to drive over to your place for a bit of "fine tuning" over a few cans of beer
GuyW

How flush does the screw head have to be? I've started countersinking, and currently have about 1/16" of the head showing. I could assemble everything and find out, but I hoped someone might know.

I started with my cheap drill stand, but it was oddly difficult to centre the bit perfectly. Strangely, the most effective method seems to be with the front plate clamped to my workmate, and a freehand drill on slow speed. Not precision engineering!
Nick and Cherry Scoop

I'm sure that will be fine, but you have to assemble the gears and flush them out,and a degree of shimming is usually necessary to get them to the same height. At least I've never been able to get the gears aligned without assembling and disassembling them a few times,but that could be just me.
f pollock

Yes, I'm looking forward to the process, too, but the trouble is, my Morris needs an MOT next week, and I've promised the next two days to it. The countersinking was just a last treat.

Just when my new dial gauge has arrived, and the package from Minispares, and I've printed off my protractor on top quality photo paper . . . . . .
Nick and Cherry Scoop

I've done it! (I think)

So please - can someone tell me if this sounds OK? My two readings for maximum lift were 115 and 94, giving me 104.5 ATDC. Peter said 106 for this cam, so only just out.

Then I just looked roughly at total opening duration, and I got 34 BTDC to 63 ABDC, total 277 degrees.

Is it worth getting a 1 or 2 degree offset key? AND, if I do, which way round will it go?

I shall do all this again from scratch in the morning, just to check.




Nick and Cherry Scoop

Hi Nick, i shouldn't worry at 104.5. I tend to allow a couple of degrees advanced but not retarded. The slight advance will also be beneficial with the smaller engine.
If you were to put a 1 degree key in, it goes so the lower part of the offset is to the left meaning the cam hasn't gone through so many degrees compared to the cam sprocket.
Peter
Peter Burgess Tuning

Nick

1.5º isn't really worth worrying about, and it is better for torque to be advanced, as it is.

If you were to move the camshaft 1º, it would move the cam timing by 2º at the crankshaft, due to the 2:1 ratio.

To retard the cam timing you would have to move the camshaft anti-clockwise, which is 'A' in your diagram.

Edit: Darn it, Peter beat me to it.
Dave O'Neill 2

. . . . and my money was on 'B'.
Nick and Cherry Scoop

Thank you very much, Peter and Dave, for your quick and reassuring answers. There's just one last question:-

I watched a video of the timing process on Youtube, and after going past maximum lift and back down to his chosen point on the dial gauge, he then ran the crank backwards, stopping at the chosen point again, reading the value off the protractor in each case.

It seemed to me that even a little slack in the timing chain might skew the second reading. Shouldn't he have been turning the crank the right way in both cases?
Nick and Cherry Scoop

You are correct Nick, only measure in direction of engine rotation.
Peter
Peter Burgess Tuning

Just to save any confusion - the offset keys move the CRANK timing by the specified number of degrees.

So a 2 degree key will advance or retard the crank angle by 2 degrees, not 4 degrees.
Chris at Octarine Services

When I commented earlier about Props advised technique I should have added that there should be no problem rocking the engine back and forward around TDC to check for TDC with the piston but as Peter has mentioned the valve timing should be checked using only engine rotation direction so any chain slack is taken out of the equation.
David Billington

I obviously made a mistake first time. I've now gone through the timing process about eight times, including dismantling the timing gear and putting it together again, and even putting the dial gauge away in its box and getting it out again.

The result is a tight group between 101 and 102.

Too far advanced, I assume?
Nick and Cherry Scoop

I would fit a 3 degree key Nick.
Peter
Peter Burgess Tuning

Thanks Peter.
Onto it.
Nick and Cherry Scoop

I've not been keeping up with this thread but thought this might be of interest if not already discussed:

http://www.mambamotorsport.co.uk/components/spridgettiming.html
John Payne

Reassuringly expensive. It's so difficult, isn't it? The Minispares chain is an AE Hepolite product - plenty of august history there, and AE stamped on every link - but is it now Hepolite of Shanghai? I will check.

OK, so it's Federal Mogul, of America and around the world. Sounds OK.
Nick and Cherry Scoop

Federal Mogul have a factory in Coventry, where they make valves, guides and seats, amongst other things.

I'm not sure where they make their chains.
Dave O'Neill 2

Just tidying up at the end of the thread. I've installed the 3 degree offset key - it needed a little mangling to make it fit - and I've got about 104 degrees, give or take, so I'm happy with that.

Thank you to everyone who helped.
Nick and Cherry Scoop

Yoku yatta Nick san
Peter
Peter Burgess Tuning

Haha....."about 104deg" - that will offend someone!
Graeme Williams

How do you jam the engine in order to get 65lb/ft on the cam sprocket nut?
The head isn't on
The gearbox isn't on
The sump is on.
Nick and Cherry Scoop

locking plate in the ring gear?
David Smith

Hi Nick,

Found these great videos which might help:

https://www.youtube.com/watch?v=rad7cdJmT6k

https://www.youtube.com/watch?v=Uhv5_-JOfmM

There is loads of other good videos from the Mini Mania team including the full engine rebuild.

https://www.youtube.com/watch?v=pnxJfrSR-OU

https://www.youtube.com/watch?v=1Jp_bhkF11w

Good luck

James
James Paul

What David said.

Alternatively, when the camshaft sprocket has holes in it, I have been known to use a 7/16" socket on an extension on one of the locating plate screws, in order to prevent the sprocket from turning.
Dave O'Neill 2

Thanks very much. I went for the ring gear, using a wife, a huge screwdriver and two dual master cylinders as a fulcrum. It was a bit precarious, as I had to hold everything down while turning the nut, but it clicked.

Locking plate would have been nice.

Nick and Cherry Scoop

Old single row timing chain looped over a 3/8 head stud placed vertically across the starter motor hole in the backplate and over the teeth of the ring gear - locks it perfectly....
Chris at Octarine Services

Chris, that works brilliantly. Thank you.

I've now put the gold timing cover on for the 5th time. I was just emptying the cam followers out of their box when a small shiny thing came with them - a little threaded plug.

I sometimes think I should not be allowed to do this on my own
Nick and Cherry Scoop

Which threaded plug would that be?

You do centre the timing cover on the pulley before tightening the set screws, don't you?
Dave O'Neill 2

I know, Dave. People like me who like to dabble in mechanical things, but have no engineering instincts, often find this an expensive hobby, I think. It was only the day before that I had been gazing at the end of the camshaft and wondering why the hole was threaded. And the day before that, I was reading about the route that oil takes around the engine. No joined-up thinking here.

Your second question : I did put the pulley on for the first four times. Number six coming up.

Lucky I enjoy it.
Nick and Cherry Scoop

This thread was discussed between 06/07/2017 and 30/07/2017

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.