Timing chain replacement

[philheys100]

Hi all,

I am changing my timing chain and I have some questions.

To change the chain only do I line up the scribe marks remove cam sprocket wrap around new chain and put back cam sprocket same way it came off?

I don't have to remove crank sprocket?

Should I change the oil thrower and how does it fit on?

Should I change oil seal, the one installed looks good?

Should I use gasket seal when putting cover back on?

Please see picture....Do the marks I have roughly marked look right?

Many thanks

[Velocita Rosso]

To change the chain only do I line up the scribe marks remove cam sprocket wrap around new chain and put back cam sprocket same way it came off?
Yes

I don't have to remove crank sprocket?
Yes you will, because  you will not be able to get a new chain over teeth in line with cam sprocket

Should I change the oil thrower and how does it fit on?
They don`t really wear just a loose push on fit

Should I change oil seal, the one installed looks good?
Yes as there will be micro wear from running on the crank

Should I use gasket seal when putting cover back on?
Yes

[philheys100]

Thanks,

So if I remove the crank and cam gear with the old chain still intact (if that is possible?) and then change the chain on a work bench keeping everything inline and taut is that the best approach??

I have decided to keep the old tensioner because its the original and the bad press about the poor quality of the after market replacements, my original is smooth and has no marks.
Whats the best technique to getting the cover back on and manoeuvring the tensioner into place?

Thanks
Phil

[philheys100]

Sorry guys forgot to ask.

I noticed that when fitting the crank wheel its a tight fit has anyone any tips so it goes on easier??

Thanks

PS Even better any videos for fitting timing chains??

[Velocita Rosso]

Quoted from philheys100

Thanks,

So if I remove the crank and cam gear with the old chain still intact (if that is possible?) and then change the chain on a work bench keeping everything inline and taut is that the best approach??

I have decided to keep the old tensioner because its the original and the bad press about the poor quality of the after market replacements, my original is smooth and has no marks.
Whats the best technique to getting the cover back on and manoeuvring the tensioner into place?

Thanks
Phil

Its a fiddly bit of work trying to fit the cover,holding with two hand and .....with a third....trying to hold the tensioner over the chain
We used a slip / loose cord onto the tensioner feeding between the c/case and cover,so when the cord is pulled tight it allows the tensioner to sit on top  of the chain.....then let go of the cord

[sparky_spit]

What VR says....   plus another tip if you are removing both sprockets with the chain still on, and in case you slip and it all clatters to the floor, is to clean a small area of chain and the adjacent sprocket and put a dab of paint on each for both top and bottom sprockets.  With them marked like this you can always put them together again in the correct orientation, on the bench and back onto the engine.

[efp]

Good tip Sparky.

And if I might add, I don’t know what you call it, but a length of that flat plastic tape stuff used to strap parcels is ideal for holding the tensioner back when refitting the cover, slips out easy.  

Cam timing can make a huge difference to engine performance and the factory marks are probably right, so be careful to reassemble in EXACTLY in the position the cogs come off. Make clear marks for alignment.

If you have the time, tools and temperament now would be a very good time to check and fine tune  the timing, but it’s a right faff, so if you are happy with the way the engine was running, just be sure to put it back the same. It’s easy to be a tooth out

[JohnD]

Two ways of replacing the  timing cover:

1/ Use a coathanger wire hook to hold the spring back against the inside of the cover.  See pic.
Dimension A depend on singlex or duplex chain, and the width of the spring.
Once in position, twist and slide out.

2/ fit the spacer  on the nose of the crank AFTER fitting the cover.  One end of the spacer has a bevelled edge.  
If the spacer is on the crank before the cover is fitted, then the bevel should be OUT.
But if you leave the spacer off and fit the cover first, A/ it's much easier to manoever it into place, and B/ the dspacer can aferwrads wbe inersted through tyhe pil sela onto the crank nose, bevel first, to that it is on the inside.

JOhn

[Tim Bancroft]

When fitting the timing chain cover, ensure that the set screws and pan head screws are put back in the right order. Easy to put too long a set screw into the alloy bridge piece and strip the thread, results in an horrendous oil leak.

Clean all the threads as well, as inevitably full of gasket sealant.

[philheys100]

Hi guys

On further inspection I need to sprockets I have found a web page on how to set the timing on the cam.
Will this do the job?

https://www.google.co.uk/amp/s.....3730591.html%3famp=1

Thanks

[efp]

I've just been through this Phl, and to be honest, that link isn't the best advice I've seen. It just says set the crank at TDC for example, but thats not so simple and to find an accurate TDC really requires a degree wheel and a piston stop.

You could just go with the marks stamped on your sprockets, but if they aren't there, or are inaccurate (quite common I understand), maybe read through this, rather long, thread. Gives several methods

http://www.triumphexp.com/phorum/read.php?8,1316080

[philheys100]

Thanks,

I am going to give it a go myself, I have all summer!!

I am going to start another thread called cam timing/chain replacement to keep with the correct theme.

Thanks all

[efp]

A thank you to JohnD for his tensioner spring retaining wire suggestion, worked better than my idea.

But may I suggest this tweak?  If centred on the spring and bent right it can hold it in place freeing up your third hand :/.   Worked for me anyway.

[Guppy916]

Take number one plug out and gently turn the engine over with a long screw driver to fell the piston moving, so easy to find TDC

[efp]

Have to disagree Mr Guppy. The piston stays unmoving at the top of the stroke for quite a few degrees of crank rotation. You need to find the centre of that period to establish true TDC or you haven’t got an accurate base position to set the cam to and the exercise is pointless.
The only accurate way is with a piston stop and timing disk, though it’s possible to get close with a dial gauge to establish the start of the period and the point at which it starts to fall and halving it.

[Nick Jones]

Quoted from Guppy916

Take number one plug out and gently turn the engine over with a long screw driver to fell the piston moving, so easy to find TDC

Easy to find approximate TDC but cam timing needs better than approximate and more elaborate methods are needed to do it accurately as mentioned above.  If the engine happens to be out there are usually marks on the flywheel and backplate.

Nick

[poppyman]

You will find TDC is when the keyway for the crank sprocket is vertical

[Steve P]

Quoted from efp

The only accurate way is with a piston stop and timing disk, though it’s possible to get close with a dial gauge to establish the start of the period and the point at which it starts to fall and halving it.

This is what i did when i installed a TLD cam in a 2.5 some years ago.Valve timing was 105 degrees ATDC from memory.
Must have been pretty close as it went like a train.
S

[efp]

Not pretending to be an expert here, have just been through this for the first time in many years having read up a lot.
Quite prepared to be shot down by those more knowledgeable.

I don’t know the specs on a 2.5 Steve, but my little 1147 has a 25/65 symmetric cam, which gives a max inlet open at 110 ATDC which is what I worked from when setting my timing, and I’m guessing is what you mean.

I understand Triumph were quite happy with 2-3 degrees or so as acceptable variance, (hence their sprocket punch marks being a bit approximate),  but variations either side of optimal have noticeable effects on performance. 4-5 degrees advanced from that will give better low end torque, 4-5 later more higher rev performance.  Or is it the the other way round? . Or it all could be complete bollocks that I’ve misunderstood..

Anyway, hence my suggestion  to establish a true TDC to work from. While the engine will start and run many degrees outside these parameters, makes sense to me to get maximum accuracy and thus performance out of the engine by getting it right while I have things apart.

I say “have” it apart, as having done the job, I found Paddocks have a double chain set up for the 1147 at a fair price so Im going to do it all over again, hoping for better accuracy.

[drofgum]

Hi,
I haven't seen it suggested  before, but it occurs to me the reason for Triumph allowing 2+ degrees of tolerance on the cam timing might be because the individual lobes weren't held closer than that to exact timing. So if number one inlet is set spot on some other cam may be off by up to 2 degrees in either direction.
                                                                                           Regards,
                                                                                           Paul

[JohnD]

Paul (drofgum),

"the individual lobes weren't held closer than that to exact timing"   On a rigid, one piece camshaft?

Or do you mean that cam machining tolerances were that far out?
JOhn

[efp]

(Stands well back to allow the grown ups to fight it out)

JohnD, see a conversation you were involved in back in 2007 in which you were scathing about vernier adjustable cam sprockets and you obviously know your stuff.
Alarmed by the amount of stretch I found in a  fairly new single chain, despite hours of setting up a new one I've just bitten the bullet on a duplex set, but disturbed to realise they are, in standard form, less adjustable than a single cog as they can't be flipped.

Have you changed your opinions on verniers since? I do realise duplex sets are strictly unnecessary on a mere 1147 in standard tune but I may come to up-rate the cam and associated bits in future and  seek to future proof it, and besides would like my hard-achieved cam timing to not drift so much as it has, and be more  bullet-proof.

Or am I over-thinking all this? No plans to race or rally my car, just want to optimise her.

[JohnD]

Did you mean this? Sorry , link no longer available

"Scathing"?  Moi?  Hardly, I have one myself.
John

[efp]

lol.

But umm..

"IMHO, a venier is a waste of money on a Triumph.
How do I know?  I have one - I wasted my money.

John "
  
Not entirely positive then?

But seriously though, ?

I can see that unless you are constantly tweaking as a racer, having found the sweet spot you'd never need to use the adjustment again, but wondering how crucial and useful you found it in finding that point. Academic, as I can't afford that investment, but curious.

cheers

John

[JohnD]

Ah!  I think my point was that its impossible or nearly to adjust the timing, except during the build.  Not on the rolling road, which is where a vernier counts.
Did I go on to relate that I built a hatched timing cover?    Even so, a vernier isn't easy to use on a Triumph.
John