Your too modest sir!

 

JB is being a touch modest here.

 

Really? I dunno...I expect its fairly accurate. I shudder to think of the repair costs!

 

Here's a bit of an update.

I just spoke to Robin (the 'horse' at Ninemeister, as in 'from the horse's mouth', if you see what I mean).

It seems that the camshaft 'pin' had come out. Now, I'm not at all familiar with this bit of the camshaft but, according to Robin, this is pretty much impossible because the retaining nut and washer (which, apparently, stop the pin from coming out) are still there and secure.

Anyone like to comment on this?

Good news is that, although all three right-side exhaust valves are damaged, the relevant pistons seem to have escaped damage.

Anyway, my engine now has to wait for the engine-building area to become free (which could be a couple of weeks) before work gets underway.

 

Hi John,

Hopefully that's good news if your pistons are unaffected?

Cheers,

David

 

I think I said this before, but the whole thing is really ironic because, in spite of now being at 100k miles, the bottom end of my engine seems to be in absolutely superb shape. And the top end, from what i can gather.

So it's far from automatic that you need to worry about big ends failing around 100k miles...

 

The pin I think Robs referring to is the dowel in the vernier cam drive.
Physically impossible for it to come out IIRC. The dowl is held in it's location by the large flat washer which is in turn secured by the bolt which holds the vernier to the camshaft itself. Is there no damage to the end of the cam itself ( or for that matter the vernier gear ?)

 

Atgani,
Is it possible for the pin to escape the cam hub by moving forward? It's not a blind hole that it sits in, but a hole that is open on the forward side where there's a cover of sorts. If indeed that's the pin and the washer is intact, then it had to slip out of the forward side of the gear.

 

mojorising Attached picture with pin arrowed. Unless the bolt securing the gear to the shaft itself has come loose (which J Bs description indicated nothing was loose/broken) the pin as you can see is retained by the large flat washer on the front and is retained (IIRC) by the flange formed on the end of the cam (so it cannot move out of either end)

 

Hiya Atgani
Great photo !
It would be nice to see a photo of John Boggianos pin / chain / guides / etc ..

 

That IS a great picture - I was having trouble visualising it until now.

Do you think it's possible that, if something jammed the camshaft for a moment (eg. the mystery piece of plastic that may/may not have been involved) then the force on the sprocket could crush/shatter the pin?

 

John, you mentioned some "plastic debris" were found, as you can see from the picture the two cam chain tensioners/guides are possible culprits for the source of these debris.
It would be interesting to know whether or not the pin is intact and undamaged.
As Rob said, it is physically impossible for it to drop out

 

That washer only just covers the edge of the pin in the photo...

 

Enough that I don't see how it could come out though. Although it doesn't cover the whole pin, it does seem to cover the entire "body" of the pin - in other words it does cover the whole edge.

 

The three exhaust valves getting bent is a clue . For all three to be bent the cam had to be turning .
At no point are all three exhaust valves open at the same time . The cam must have been turning for all three exhaust valves to be bent . The motor ran ? But ran with a knock ?