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

19 minutes ago, johny said:

Ouch yes maybe easier without plugs in especially for fine adjustments🙂

I thought I was being clever not risking getting the spark plug leads mixed up, but with hindsight...

I could just have labled the leads!

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

57 minutes ago, johny said:

Yes I think youve demonstrated the problem but by putting the cam in the rocking position you'll be able to see how many degrees away from TDC the crank is. This might even give you an idea of whether youre a tooth, half a tooth or even a quarter of a tooth out on the cam sprocket... 

Thanks. I'll be having another go on Monday (assuming the skin grows back on the hand I was using to pull the fan belt to turn the engine). 

If I understand you correctly, my tests today confirm that the cam timing is off, and finding the rocking position will tell me how much it's off.

Onwards and upwards!

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

Just to (hopefully) clarify that I'm not a total idiot, this is why I span the crankshaft to TDC after opening the gaps on rockers 1 & 2:

 

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

I'm starting to think we're reaching the "too many chefs" point of the conversation.

I'll take the rocket off and have another play on Monday (hopefully), but I'm just getting more confused what I'm meant to be doing.

Maybe time to drive to a garage with a qualified engineer.

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

25 minutes ago, johny said:

My emphasis.   You set the gaps wide on valves 1 and 2?   That are on cylinder no.1?     That would be completely wrong!

One of these quotes has to be right....

That's the manual I was following. The quote you shared says adjust number 1 (and later number 2) rocker. But you're saying I shouldn't have adjusted rockers 1 & 2.

I'm confused.

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

Very good point about 2 TDCs.

Now you've put some doubt in my mind if I did it right. If the crank was on the exhaust stroke, the exhaust valve would be wide open at TDC, and I'm pretty sure both were closed. But, before I start taking the engine apart, I'll do the check a 3rd time, maybe the way you describe this time (finding the rocking position, rather than setting to TDC).

The earliest I'll have time is Monday, so another installment will follow!

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

Ok, the latest chapter of my saga.

I did the check on cam timing using the "rocker method" (as described in the workshop manual), and there might be something wrong. Assuming I did it right, after setting the gaps to 0.04" on 1 & 2, then spinning the crank around to TDC, the gaps were not the same. #1 had no gap, and #2 0.004".

I did it all twice just make sure I didn't just make a mistake setting the gaps to 0.04".

I've reset the gaps to 0.01" on all rockers and put the car back together as I need to use it next week.

Does everyone think the timing chain cover needs to come off?

Any other suggestions before I start such a major project (I assume I'll have to drain the cooling system and remove the radiator before I even start to try and remove the nut on the end of the crankshaft, and do I even have a spanner/socket that size?).

Also, huge thanks to everyone that's offered suggestions so far, it's been a real boost to my confidence.

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

6 minutes ago, Pete Lewis said:

do make sure you have tested /measured/cussed and swore to find what you have before you go jumping into untested territory

based on any bright ideas we have posted ,   

Pete

Don't worry, I'm very much a "if it ain't broke, don't fix it" type owner, which is one of the reasons this problem has been ignored for so long. I'll be making damm sure the cam is in the wrong position before I start dismantling anything!

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

14 minutes ago, johny said:

Orrrrr you might have accidently found a set up that boosts power over the standard output😳

That would be quite upsetting!

Having a car that runs as Triumph intended is nice, but it will be incredibly annoying if after hours of work, it runs less well with the cam in the right position! (assuming it is currently in the wrong position)

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

21 hours ago, Ian Foster said:

It is possible that the cam was installed incorrectly. The check procedure will show if it is out.

Ref Pete's question above, is this a new or longstanding issue?

Ian

Longstanding, but I only recently discovered just how far from "spec" the ignition needs to be for the car to run smoothly.

I really hope the cam was installed incorrectly, as I'll be expecting a big boost of power once it's fixed (and better MPG)!

[Someone getting an electric convertible Vitesse?]

I spotted a red convertible Vitesse in the background of this video about electric car batteries. It appears at around 1:55 and again around 2:05.

 

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

40 minutes ago, Ian Foster said:

It is possible that the cam was installed incorrectly. The check procedure will show if it is out.

Ref Pete's question above, is this a new or longstanding issue?

Ian

It's a long standing issue that any time anyone has ever tried to set my ignition timing correctly, the car is virtually impossible to drive, until the timing is reset 'by ear'.

It's only recently I've discovered how far from spec. my timing needs to be set to actually go.

I'm looking forward to checking the cam timing. I'm sort of hoping it's wrong, although that will be a fair amount of work to fix.

If it isn't that I'm pretty much out of ideas!

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

3 minutes ago, Pete Lewis said:

general tappet adjustments are use rule of 13  and 0.010"  on a cold engine 

rule 13   1 down  set 12      10 down set 3   etc 

if the rocker pads are worn then feelers will bridge the wear and give a false feel to the feeler fit 

Pete

I had a reconditioned engine fitted about 15 years ago (with hardened valve seats for unleaded petrol), so there shouldn't be 50 years of wear to worry about, and those 15 years haven't been high mileage.

I wonder if my timing issues originate from that engine swap? I probably drove it for several years trouble free without ever checking the ignition timing.

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

43 minutes ago, Pete Lewis said:

basic rules are you turn engine so rockers 11 &&12 are on the rock/in balance  (one going down one coming up) 

set rockers  1 &2   tappets to 0.050"   turn engine  to align TDC for no1 on compression   and then measure the tappet gaps on the wide setting   doesnt  matter what the gap is so long as they should both be the same /equal .

any variance needs a bit of chain/sprocket twiddling on another day 

the cam sprocket has 4 holes and the sprocket can be turned over this will give each fixing at 1/4 tooth  adjustments increments.

so with a good pair of glasses and six hands its quite easy and adjustable if its needed 

Pete

Another project for next weekend!

Even if this doesn't reveal anything wrong, it's a good excuse to check and adjust the tappets, which haven't been done for a while.

As always, I'll report back once I've done the work and washed my hands!

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

1 hour ago, johny said:

Ah you need the free to download bible kindly offered at vitessesteve.co.uk

Downloaded, and I've found the section on checking the cam timing. 

This will be very useful in the future, not just while I'm scratching my head over timing advance.

Thanks for the link.

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

On 19/08/2023 at 17:35, johny said:

You could do it from the cam sprocket marks or the rocking valve method as described in the workshop manual which uses the position of cylinder 1 inlet and outlet rockers at TDC to indicate correct cam timing...

I only have the Haynes Manual, not the official Workshop Manual, and as far as I can tell, it doesn't contain anything about checking the cam timing using the "rocking valve method". Do you know if a description of this has ever been published online?

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

30 minutes ago, Pete Lewis said:

all this  but why?????       has the car had a long standing problem or has a problem arrived out the blue ????

{Pete

It's been a problem I've been ignoring for years, but something's not right and if I can fix it, I'd like to.

A problem is still a problem even if it's old.

The first job is to work out why the timing is so extreme.

Edit: If I fix it, I'm hoping for better performance or better MPG, or maybe both.

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

35 minutes ago, johny said:

You could do it from the cam sprocket marks or the rocking valve method as described in the workshop manual which uses the position of cylinder 1 inlet and outlet rockers at TDC to indicate correct cam timing...

I'll do some research!

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

1 hour ago, Pete Lewis said:

cam timing or dodgy strobe  ??

I don't think it's a dodgy strobe as whenever anyone tries to tune the car with a strobe it ends up awful, not just me.

I assume I'd have to remove the timing chain cover to check the cam timing?

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

Update!

I did a few tests this morning. 

1) The timing marks seems fixed firmly to the pulley. No way I could move them in either direction, even with a screwdriver wedged into the TDC marker.

2) With the plug out of cylinder 1, I could easily feel the piston position with a screwdriver and although it doesn't move much at the top of the stroke, I could easily detect movement around 10 degrees before and after the TDC mark. So it seems the TDC mark is in the right place.

3) This time I took a photo of the strobe at idle (a smooth 650rpm). The mark is showing more than 20 degrees BTDC. 

4) When rev'ed to 2000rpm, the timing mark is so far advanced, it's not visible from the angle the photo was taken at, so maybe 40 degrees BTDC! Even when set 'by ear' and running smoothly,I have noticed a lack of power at high revs and open throttle (e.g. accelerating from 50 to 70 in top gear).

5) When removing spark plug 1, I noticed the mixture was a little rich. Nothing too extreme, but worth noting. I would have expected a lean mixture given the K&N air filters.

So that's all the latest news. Any idea what to try next?

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

2 hours ago, JohnD said:

Nicr,

I can't test your entire car. much as I'd like to.  Post me your crank pulley, which weighs 1600 grams and would cost (with less than 400 grams of cardboard) a bit over £6 First Class .

John

That makes a lot more sense than my idea!

Hopefully it will not come to that. First I need to inspect the pulley, then try setting the crankshaft to TDC then see what the timing indicator position is.

After that, maybe I'll think about removing the pulley, but it's something I'd prefer to avoid, especially as the car is currently drivable with its weird timing advance setting.

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

26 minutes ago, JohnD said:

Believe it or not, the Post Office does provide an excellent service, even to those parts of the UK that do not speak 'Received English'.

John

I dread to think how much it would cost to post a GT6, even second class 

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

7 minutes ago, JohnD said:

Nicr,

Please PM me?  And we may swap addresses.  I'm in Northwest England, but with respect, I'd prefer not to publicise online where I live!

John

If you're in NW England you probably don't need to share it with me either as I'm in SE England!

Thanks for the offer anyway!

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

23 minutes ago, Colin Lindsay said:

Are the sparkplug leads fitted to the cap correctly, or is each rotated incorrectly by one position round the cap?

The strobe is triggered by the spark to plug 1, so I'm not sure what difference that would make, apart from the position of the distributor, but I'm open to suggestions.

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

16 hours ago, JohnD said:

Nice guy,

My thanks to Pete for taking up my sermon!   

Yes, in the situation you describe, very much worth checking where TDC really is, with a piston stop and a degree wheel on the crank.   But if you can move the outer ( "inertia ring") part of the crank pulley on the hub, then clearly the rubber joint that does the damping has failed.    If you are in any doubt, send it to me, and I will check it on my test rig.

John

John, I forgot to ask, when you say "send it to me", just out of curiosity, where are you?