Timing Gear set

[ScuRoo]

Hmm... this gear thread has been wrestling in my mind so I need more pertinent info...

Q: All things being equal on V11’s whether stock or even warmed up a bit like HC pistons, Xovers, pipes etc., - by adding these gears & thereby in particular gaining greater accuracy/stability in timing at higher rpm’s - to what extra degree could one reasonably up the rev limit??

All things being equal that is.

500 extra rpm? 750? A thousand...?

Appreciate if anyone could give me some idea on this...

Trying to find a singular performance compelling reason to get my head over the huge cost!!

If there’s no lift in rpm I really can’t justify it imo - the stock chain isn’t actually a negative - however if there is a viably safe increase... 🧐

Ya know... every dawg needs just a little meat on the bone to clean off to stay interested! 🍖

 

🐶 🦴 

[pete roper]

The governing factors are going to be issues such as valve float and rod integrity rather than timing when talking about the cam drive.

[Lucky Phil]

2 hours ago, ScuRoo said:

Hmm... this gear thread has been wrestling in my mind so I need more pertinent info...

Q: All things being equal on V11’s whether stock or even warmed up a bit like HC pistons, Xovers, pipes etc., - by adding these gears & thereby in particular gaining greater accuracy/stability in timing at higher rpm’s - to what extra degree could one reasonably up the rev limit??

All things being equal that is.

500 extra rpm? 750? A thousand...?

Appreciate if anyone could give me some idea on this...

Trying to find a singular performance compelling reason to get my head over the huge cost!!

If there’s no lift in rpm I really can’t justify it imo - the stock chain isn’t actually a negative - however if there is a viably safe increase... 🧐

Ya know... every dawg needs just a little meat on the bone to clean off to stay interested! 🍖

 

🐶 🦴 

There really isn't a compelling technical reason to install the gears with the exception that you do away with a cam chain tensioner and the inertia of a double row chain flailing about. If you need to renew the cam drive system and tensioner because of wear and add up the cost of the new Guzzi components then the upgrade to gears isn't to expensive at all. Docc did the numbers on it a little while ago.

Ciao

[ScuRoo]

...still chewing on this...

So... I noticed on Pressureangle’s post his pic (which I’ve magnified) the top spur gear overlays another gear behind!

Huh?

My question is - so what is this doing?

Guess it’s driving something.

Can this be lightened also?

[MartyNZ]

3 hours ago, ScuRoo said:

So... I noticed on Pressureangle’s post his pic (which I’ve magnified) the top spur gear overlays another gear behind!

Huh?

My question is - so what is this doing?

Guess it’s driving something.

Can this be lightened also?

That's the phonic wheel. As the teeth go past the rpm and TDC sensor, the sensor gives this information to the ECU. Now you mention it, it could be lightened, but just not the diameter or tooth mass.

[ScuRoo]

Cheers for that MartyNZ!

Those two gears sandwiched together just looked a bit incongruous especially when the gear in front is max’d out with all those lightning holes!

Hmmm okay then... possibly more outlay in custom machining in the course of Joe’s gear installation.

I mean, if you’re going to do it - right?

Minimising rotational weight has additional appeal - makes sense if considering going to those extra lengths of investing in timing gear$

Do you think a someone’s been there done that...?

Proportions may be a little large but here’s a quick mock-up of 10/tenths of extra squeeze!

 

[docc]

On 7/20/2021 at 8:28 AM, docc said:

Joe replied to my email immediately and offered considerable additional information that I will try and post later. I believe much of this has been included in Lucky Phil's installation thread.

Joe did say there are Daytona and V7 gear runs ahead of the V11, so ours will probably be by the end of the year. The cost of £675 UK Pounds is, today,  $924USD  ($1258AUD)  including shipping (to the USA).

I suppose we are approaching the end of the year and no word on gear set production. I'm not going to pester Joe, but hope that we are getting closer to a production run. I'm in no hurry as I'm just getting them to put under my pillow at night to keep the bad timing juju at bay . . .

[docc]

I need to learn to be be more patient….

Just a couple days after I posted above, I hear from Joe! He says the job has made it to the shop floor. Accounting for the heat treating, completion is expected  February. Joe is also making the relieved cam flange available.

[motoguzznix]

On 7/20/2021 at 9:16 PM, Pressureangle said:

I'm 99% in accord with this, *but* there is that 1%. I've attached a photo of a Camshaft for illustration. On a big block Guzzi, all four cam lobes are on the same side of the cam. A compressed valve spring returns all of the energy input on the opening ramp back into the rotation of the camshaft on the closing ramp, minus heat losses through friction; on the ramps where a valve is closing at the same time another begins to open, the opening ramp 'catches' the closing rotational forces and *probably* cancels them. On the other side of the cam, though, there are two closing ramps with no opposing opening ramps to prevent them rotating the camshaft into whatever slack there may be in the chain, or perhaps overcoming the weak stock tensioner. Worse, they close at the same time doubling the effect. I believe that's the source of the spark scatter at idle, and I won't assert but remain open to the possibility that the ~3k rpm dip may be some function of chain slack and resonant property stack in the components. 

 

I also agree that this is the reason for the spark scatter at idle. The frontmost cam on the shaft is the last one to be active and therefore can rotate "back" when the follower is over the nose of the lobe. In fact it does not rotate back but shaft rotation ist slower before and faster after passing the top of the lobe. On old engines driven for a long time with chain slack, you can see a flat on the front cam...

This is not just a theory, it can be proven - install a valtec type chain tensioner and check spark scatter with a timing light - you will see it disappeared compared with the slacky stock tensioner.

[ScuRoo]

Got into a chat with a specialist LS V8 performance engine builder at our local Italian mercato the other day... I mentioned timing gears & he wasn’t a fan. He liked chains, specifically... Cloyes.

Wasn’t a fan of the added gear vibration.

His answer surprised the heck outta me!

So later on I started googling “timing gears” & “vibration”... seems it can occur.

Gear noise = vibration + heat 

 

 

Fomo is strong in me... must ugh, resist!
🍿😋

 

[80CX100]

1 hour ago, motoguzznix said:

This is not just a theory, it can be proven - install a valtec type chain tensioner and check spark scatter with a timing light - you will see it disappeared compared with the slacky stock tensioner.

When I did the timing chain and installed the Valtec tensioner on my CX100 it only had 24k miles on it, but it was loose and sloppy enough to have started to wear inside the case.

You could really feel a difference in how much tighter and uniform the whole ignition timing/firing system was.

fwiw

[Lucky Phil]

1 hour ago, ScuRoo said:

Got into a chat with a specialist LS V8 performance engine builder at our local Italian mercato the other day... I mentioned timing gears & he wasn’t a fan. He liked chains, specifically... Cloyes.

Wasn’t a fan of the added gear vibration.

His answer surprised the heck outta me!

So later on I started googling “timing gears” & “vibration”... seems it can occur.

Gear noise = vibration + heat 

 

 

Fomo is strong in me... must ugh, resist!
🍿😋

 

It's worth bearing in mind that you can't as a general principle translate everything in engineering across all installations and applications. What works perfectly fine in one application can have issues and problems in another. From my sketchy memory gears weren't favoured by NASCAR engine builders because in the operating envelope they ran at harmonic vibrations were an issue with gear driven cams. Chain driven cams dampened this out. Remember though this is/was pushing an original design to it's limits and a lack of rigidity in cranks combined with sustained high rpm introduced it's own issues unique to those engines.

It's what makes engineering interesting and challenging and keeps designers awake at night. It worked here on that, so it "should" be ok on this, then it turns out it's not and back to the drawing board, testing and investigating. Rolls Royce engineers and designers spent 5 years of the war on a merry go round like this developing the Merlin and Griffon engines among others. Quite often it was a minor modification required or a materials change and the issue was solved.

Ciao

 

 

[Weegie]

7 hours ago, Lucky Phil said:

It's what makes engineering interesting and challenging and keeps designers awake at night. It worked here on that, so it "should" be ok on this, then it turns out it's not and back to the drawing board, testing and investigating. Rolls Royce engineers and designers spent 5 years of the war on a merry go round like this developing the Merlin and Griffon engines among others. Quite often it was a minor modification required or a materials change and the issue was solved.

Ciao

 

 

If I had to pick one engine that contributed to defeating Germany in WWII it would be the Merlin. RR's policy under Hive's was to focus resources on development of what they knew worked, then gradually "stretch" the design. Supercharger and associated gearing being the main focus, but many many others. That's why the Griffon was so late and the Crecy never happened.

From what I've read RR policy with new engines was to stick them onto the test stand run them till they broke, then take them apart fix it and run 'em again till they broke...........ad nauseum.

IMHO it was brilliant leadership and vision, should Germany have developed the same strategy the allies might have been in a lot more trouble than they already were.

I'm in total agreement with Phil and everything he stated in the post above

To Joe's gears, got them in my LM 1000, Sport 1100i and HiCam, was it @Pressureangle who stated he felt the engine ran better? I'm of the same opinion.

Valtec tensioners can have their problems too, but at the end of the day we just all weigh up the pros and cons of each offering and decide what suits us as individuals best

[ScuRoo]

9 hours ago, Lucky Phil said:

It's worth bearing in mind that you can't as a general principle translate everything in engineering across all installations and applications. What works perfectly fine in one application can have issues and problems in another. From my sketchy memory gears weren't favoured by NASCAR engine builders because in the operating envelope they ran at harmonic vibrations were an issue with gear driven cams. Chain driven cams dampened this out.

Harmonic vibrations...

Had no visual comprehension on how an engine created these - I guess I just kinda assumed it was produced by the combustion bangs💥

...turns out it’s more related to the stroke travel speed differentials!

Amazing F1 in-depth explanation in 1st half of this vid (the 2nd half is pure tech-sex!) just learned me!

But... it’s in the noggin’ now! 

 

[80CX100]

4 hours ago, Weegie said:

Valtec tensioners can have their problems too, 

Absolutely. 

Not being naturally mechanically inclined, I research every job I do, ad nauseum.

I had read many times on the difficulty of getting the new Valtec tensioner into proper position and that it was tough, it wouldn't break, just force it into place.

I proved that theory wrong and the brittle plastic broke right at the metal support/pivot post, and I had to order a replacement.

I think I was lucky that it broke right before my eyes and I had a chance to correct the problem with a new one. More gently installed the 2nd time, by disassembling it, and reassembling it in proper position.

I've subsequently read of a catastrophic engine failure due to the Valtec breaking apart, hidden out of view; I'm sure that the point of failure was at the same stress point, but if it cracks during installation and you don't realize it, you can pay a high price later on for an obvious weak spot in the design.

fwiw ymmv