[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

9 minutes ago, Iain T said:

Best practice is take copious amounts of photos and mark where everything is now. 

Iain 

I'm trying to, but you can guarantee that I haven't taken a photo of something that I've forgotten where it went!

It doesn't help that my phone refuses to unlock when I have greasy fingers! I need to set up facial recognition!

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

10 minutes ago, johny said:

Anyway youve got clear problems one by one, testing between each and eventually youll reach perfection plus have great fun doing it😂

So far, I'd say it was interesting more than fun. If there is any improvement at all in how the car drives, it will be very satisfying.

At the moment I'm preparing myself for the big step of actually removing the timing chain, and trusting myself to be able to put it all back together again! So far, I've been confident that everything I've done was reversible if I needed to drive to a mechanic!

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

12 minutes ago, JohnD said:

My misstype!  For 1/2 tooth!

But ... were you aware?

And ... that tiny degree of cam mistiming will NOT be the cause of your need for very advanced ignition timing!   You're focussing on a trivial fault.

John

I only started down this route based on advice that incorrect cam timing could be the cause of my odd ignition timing.

Do you have other explanations for my need to have very advanced ignition timing? I am very open to new ideas.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

1 hour ago, Puglet1 said:

Well Nicrguy. Nothing for me to contribute other than to say what a fantastic forum this is.  
You have got the “Top players” supporting you throughout a very difficult problem. 

If the rest of mankind had the same attitude as these guys I think the world would be a much better place for everyone. 👍

I quite literally couldn't have done this job without the help I've received from this forum.

From the start, identifying that cam timing could cause off ignition timing, to providing a link to a download of the WSM to find the cam balance point, to tricks on how to removing the crank nut, and finally, how to get to the crank cog.

So many times I'd have been forced to give up and take the car to a mechanic.

I can't stress how grateful I am for all the help offered.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

53 minutes ago, JohnD said:

Are you aware that the cam sprocket may be rotated to achieve valve timing down to less than 1/4 tooth?   Thus is  by the four bolts, of which the two pairs are slightly off set.

From WSM, p. 1.138:

"NOTE: The camshaft timing sprocket is provided with four holes which are equally 
spaced but offset from a tooth centre. Half tooth adjustment is obtained by rotating the 
sprocket 90 degrees from its original position.  A quarter tooth adjustment may be obtained 
by turning the sprocket "back to front". By rotating it 90 degrees in this reversed position, 
three-quarters of a tooth variation is obtained. After securing the sprocket, re-check the 
timing to ensure that the camshaft has not been disturbed during this operation."

The last refers to the crank being in TDC on 1 and 6.

John

 

 

That sounds like a quarter of a tooth, how is it "less than 1/4 tooth"?

Not that I'm trying for perfection, just to make my ignition timing "normal" (and maybe increase HP a little).

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

2 minutes ago, johny said:

Thats the way and at the end of the day valve timing is never going to be absolutely perfect because of chain and sprocket wear. Of course you could always do this job every few thousand miles to keep it closer😱 On that front how worn is your chain compared with the manual measurement?

Seems fine. The engine was reconditioned about 15 years ago, so most things are in fairly good condition. I'm assuming the guys that rebuilt the engine got the cam timing wrong.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

3 minutes ago, johny said:

No idea as Ive never done this😂

1st time for me too!

I've done "big jobs" like piston rings and bearings before, but this is far more delicate and fiddly than I'm used to.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

8 minutes ago, johny said:

One thing, did you open up both 1 and 2 tappet gaps to 40 thou as recommended in the manual? Its just that the  3 thou youre measuring on balance point is quite tight so a measuring error of 1 thou in 3 is a lot more than 1 thou in say 10... 

Second answer to same post!

Yes, 3 thou is very small, when I was turning the crank I basically had a gap in tappet 1 or 2 with the other closed, until I found the balance point and could get a 3 thou feeler gauge into both.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

5 minutes ago, johny said:

One thing, did you open up both 1 and 2 tappet gaps to 40 thou as recommended in the manual? Its just that the  3 thou youre measuring on balance point is quite tight so a measuring error of 1 thou in 3 is a lot more than 1 thou in say 10... 

Yes I opened them to 40 as described in the WSM. What gap would you expect to see at the balance point?

Sunday lunch is calling, and there will be wine, so although I'm happy to carry on chatting, I'll not be doing any more work on the car today.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

2 minutes ago, johny said:

And I take it youre no longer on TDC either? So yes next step is undo cam sprocket and remove it so that crank can be turned to TDC. As it looks like an error of half a tooth you then have to rotate the sprocket 90º before bolting it back on through the second set of holes.... 

The chain is still on, so no, the crank isn't at TDC now the cam is at the balance point.

Now I'm wishing I'd loosened the cam sprocket before getting to this delicate point!

I guess I'll be finding the balance point again as the cam is bound to move when I'm removing the bolts.

Hindsight is a wonderful thing.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

1 minute ago, Pete Lewis said:

eed to get the cam lobes in balance and exactly mid point highest point   

best use a dial indicator to get the centre of the cam ramp 

pete

If I had one, I would!

I'm following the workshop manual method of opening up the gaps on rockers 1 and 2 (when valves 12 and 11 are fully open), then setting the cam so both 1 & 2 have the same gap (3 thou in my case).

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

This is what the cam gear looks like when I've found the balance point.

I'm thinking the cam timing mark is half a tooth from where it should be.

So the next step is to remove the chain and set the cam to this position when the crank gear is at TDC?

Am I understanding the process correctly?

I'll wait for some replies before proceeding as this is the most important step.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

Shim is off! (and I checked, the Haynes manual didn't say anything about taking it off it before removing the Woodruff key. Grrrr).

I also realised that if I remove the Woodruff key, I'll have no way of turning the engine to do the rocket balance point measurement.

The marks might be a tad off now I can see all 3 (crank, engine and cam), but nothing like the 6 degrees I think I found before taking everything apart. Maybe 1/4 tooth?

Now to repeat the rocker measurement while I can see the marks to see if they are in the wrong place.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

1 hour ago, johny said:

you cant remove the key with the sleeve in place and anyway as I say you dont need to. Beware they are pretty soft and can get mangled quite easily....

Thanks. I missed that when reading the manual!

That's probably why I was having trouble!

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

1 hour ago, johny said:

While resting you can check the chain tensioner and seal in the cover👍

I've bought a new seal and gasket. The tensioner looks as good as new.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

7 minutes ago, Josef said:

Take a brass drift and hammer on one end of the woodruff key. They’re half moon shaped so that’ll push one end down and the other up. 

It would have been nice if the Haynes manual had mentioned that! I've packed up for today, but something to try tomorrow.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

9 minutes ago, johny said:

When ready and engine at TDC you need to check cam is at its rocking point again because those lines could have been scribed in the wrong place....

That's exactly why I'm taking it all apart!

From the rocking point, I'm fairly sure the cam timing is wrong, but the marks day it's correct, so I'll do another rocking point test and see where the lines are then (I've never seen the lines until this morning).

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

Enough grazed knuckles for today. I'm happy with the progress I've made.

If there's a special trick to removing the Woodruff key, please let me know. Does it just slide forwards towards the front of the car, or does it also need to be lifted at the same time, or some other secret maneuver?

I'll let it soak in WD40 and try again tomorrow.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

6 minutes ago, johny said:

Youre looking for this:

If (when) I get the Woodruff key out, I will.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

8 minutes ago, johny said:

you need to go a little further and pull off the sleeve the cover oli seal runs on and the oil flinger disc behind it to see the mark on the small sprocket...

I'm having a little issue with the step "Remove the Woodruff key from the crankshaft nose with a pair of pliers". I've tried pliers and a small mole wrench and it hasn't budged at all.

So I'm a stuck again for the minute.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

5 minutes ago, Iain T said:

Is the engine at TDC? 

Iain 

Yes, after taking it all apart, I put the cover and crank pulley back on to set it to TDC (I had already set it to TDC before taking it apart, but when I removed the timing chain cover I discovered the cam was 180 degrees out. 50/50 chance, just my luck!)

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

Timing chain cover is off, and I can see the timing mark on the cam gear. Sadly it looks perfect!

I'm not that surprised as the mechanic that I spoke to told me that whoever built the reconditioned engine would have put the timing marks on, so if he had the cam on the wrong place, the marks would be in the wrong place too.

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

19 hours ago, Puglet1 said:

In days of old, I have seen a skilled mechanic attach a very good fitting ring spanner or socket and Tommy bar to the nut, ensured that the spanner was resting safely against the chassis , distributor cap removed and the starter motor “flicked “ to unlock the nut. Make sure you are happy with the position of the spanner before doing so. 

It sounded crazy, but I tried it, and it worked! (After fixing the other end of the ring spanner to the chassis with cable ties just in case it decided to fly into the bonnet or windscreen!)

The crank pulley bolt is off!

Any other steps that are likely to be this difficult?

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

11 minutes ago, Iain T said:

Asked my wife nicely to do just that after I couldn't stop the engine from turning. 

Iain 

I asked my wife nicely this morning, and was told that I'll have to wait until she's done her morning exercises. I thought about suggesting that her morning exercise could be freeing a stuck bolt, but decided better.

Soaking overnight with WD40 achieved nothing. Currently hammering the ring spanner, no movement yet.

I wonder where I can get 1m of scaffolding pole?

[GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?]

37 minutes ago, RedRooster said:

I wouldn't, there's a rubber ring in the damper. 

Thanks for the warning.