On 12/1/22 12:51 am, Noddy wrote:
> On 11/01/2022 7:51 pm, Grumpy Tech wrote:
>> On 11/01/2022 6:35 pm, Xeno wrote:
>
>>> Yeah. Didn't understand the concept of valve *float* and valve
>>> *overshoot*, both circumstances that can lead to valve impact if
>>> insufficient clearance is allowed - and a thinner shim head gasket
>>> will take that clearance down by a *lot*. I didn't expect Darren to
>>> be able to do it but I did expect Daryl to know how it's done. He is
>>> *supposedly* qualified after all. Too much time pushing a broom I
>>> guess. Checking piston to valve clearance isn't rocket science by any
>>> means and there's plenty of info on the net for the uninitiated. But
>>> to fit a thinner head gasket and *not* check the clearance, that's
>>> nothing short of *criminal*.
>>> The funny thing is, I was expecting it to be a more esoteric cause,
>>> lean combustion, injectors at 100% duty cycle or MAF sensor pinning.
>>> I was overthinking it and not making sufficient allowance for the two
>>> clowns who were working on the 4AGE(20). I trust Les has learnt his
>>> lesson.
>>>
>> So it's his fault the engine failed even though he advised Les that
>> there were serious issues with the engine and failure was likely.
>
> Actually, it was *not* my fault that the engine died, and I'll go into
> some detail as to why that is to put this ridiculous bullshit claim of
> Clasener's to bed :)

You worked on it, you didn't understand the *need* for clearance checking.

<snipped irrelevant bullshit>
>
> This is with the cams removed obviously, and the various markings on the
> head show where I'd been measuring clearances and swapping shims around
> to get within spec.
>
> The 4AEG engine uses a cam follower bucket system as can be seen, with
> the clearance adjustment shim being a small pad not much bigger in
> diameter than the valve stem that sits in a recessed pocket in the
> bottom of the bucket between the bucket and valve tip. The come in

So what? The Marina had that exact same system and they hark back to the
*70s*. Done lots of them during overhauls and head work. If the OHC head
uses decent valves and seats, then valve clearance adjustments *in
service* are rare. Usually they only need setting if valve work is being
done for some reason or the engine is being overhauled.

> various thicknesses, but unless you have access to a great many of them

I had boxes of them, all size marked. Even measured and marked the
second hand ones I amassed. Did you know you could buy them in *sets*?
They weren't expensive. And you got to charge them out to the job if you
had a *real business*. It Ok, we know your business was fake.

> setting the valve clearances on engines like these can be a pain.

Just need to follow the process, measure clearances, remove shims and
measure those, calculate new shim sizes and refit to suit - IOW, be
methodical. Time consuming but not a pain, especially given they rarely
go out of adjustment in service. In fact, if the valves can be kept
cool, you may never need to do a valve adjustment in the *service life*
of the engine. Used to do a lot of work on the old side valve Ford V8
engines. No means of adjustment whatsoever is provided for valve
clearance. All you can do is remove metal from the stem tip and that
will normally only be done at rebuild time. especially since you need to
remove heads and valves, including guides, to do it. Never had to do
clearances on one of those outside of rebuilds. Hmmm, that would have
changed once they removed the tetra-ethyl lead from petrol, valve seat
recession and all. Stelite faced valves and seats would be the go there.

> Especially when the people doing the cylinder head work aren't all that
> concerned about how much they cut out of the seat or they grind off the
> tip of the valve.

It's the job of the engine builder, don't sweat it.
>
> It took an entire day to set the clearances using the limited assortment
> of shims that I had, and in the end I had to grind many of them on the
> surface grinder using a custom jig to hold them securely on the magnetic
> chuck.

Been there, done that, so what.
>
> Finally, the clearances were set and the camshafts installed for good,
> and it was ready for it's timing belt and to be put back into the car.
>
>> https://www.imagebam.com/view/ME69S4W
>
> So, after all this long winded chest beating, what have we learned?

What have you learnt? Likely nothing at all. But you do a hell of a lot
of chest beating. In fact, that's all you do.
>
> What we've learned is that apart from a little bit of piston to bore
> clearance variation which Les was advised could lead to a bit of ring
> flutter and oil control problem, this engine went together well and had

Piston to bore clearance does not lead to ring flutter. What does cause
ring flutter is excessive ring side clearance or reduced ring radial
pressure. Designers usually aim to put ring flutter up at the top end
above the engine's RPM range. They do this by addressing piston speed,
piston stroke, ring mass and sealing forces. Another case of not
understanding the theory so not being able to diagnose the issue.

> no clearance issues whatsoever. The engine was installed back into the
> car and test fired by me and it fired straight up with excellent oil
> pressure and had no temperature issues.

Temperature issues rarely occur under no load situations.
>
> At this point the car was handed back to Les were it was booked into a
> dyno session. It ran the dyno session successfully where it bed in
> nicely, and as Les was still playing with tune settings a second dyno
> session was booked not long after. Subsequently to this it did a full
> test and tune day at Winton raceway before it was packed onto it's
> trailer and taken to Bathurst for a class race meeting which was the
> ultimate purpose of having done all this work in the first place.
>
> And it was at Bathurst where things turned to shit.

And on/at the end of conrod straight, as could be expected given the
circumstances of operation.
>
> On the seventh Lap of Les's race, as he was coming through the Chase at
> the end of Conrod Straight, the engine had a change of exhaust note and
> blew a heavy plume of white smoke out of the exhaust. It was
> instantaneous, and it was abundantly clear that something in the engine
> had broken, and it's race meeting was over.

Of course it would. It dropped the valve head and put a hole in the
piston FFS. And cracked the bore. White smoke, oil or water, either is
possible. The piston hole - bluish white, the bore damage - pure white.
I'd say water entering the bore through the crack caused the white smoke.
>
> Les returned to Melbourne and brought the car around for me to look at
> where he showed me the video of the failure taking place, and after
> pulling a plug and looking into the cylinder with a Borescope it was
> obvious that the engine had dropped a valve and suffered a terminal
> failure.

A terminal failure caused by a terminal cockhead. Well done you!
>
> I didn't do anything else to it, and Les went home with his tail between
> his legs and pulled the engine apart to see for himself. Once he did, he
> sent me these photos.
>
>> https://www.imagebam.com/view/ME69PMI
>> https://www.imagebam.com/view/ME69PMH
>
> What these pictures show is that an exhaust valve on number one cylinder
> has hit a piston, but moreover it did so while the valve was fully open
> at the limit of it's travel. That much is obvious from the fact that the
> valve was snapped off around half way up it's stem, and as the piston

It's where the valve heads *always* snap off. The reason, it is the
*hottest* point of the valve which also happens to be the furthest point
of the valve away from any cooling medium.

http://lh6.ggpht.com/_Ii1ukGkfijY/SpGsq0DhKDI/AAAAAAAAA1w/mkiXQ24wbpM/clip_image0048_thumb.jpg?imgmax=800

You get the valve hotter than normal, the integrity of the metal in the
800 degree region will reduce increasing the risk of failure. I have
detailed the process elsewhere. It's obvious to anyone who understands
engine theory but that is not you - obviously. I've said it before and
I'll say it again, excessive valve temperatures are the most common
valve killer. It's what caused Les' valve to fail, that much is obvious.

> turned it sideways and tried to bury it into the seat pocket it caused
> the piston to rock in it's bore pushing it hard up against the cylinder
> wall and splitting it open.
>
> Anyone who has even the most "basic" of engine experience will tell you
> that this is most decidedly *not* the result of inadequate piston to
> valve clearance :)

It is when you look into why the valve lost its head - heat. Piston taps
valve, even if only just slightly, causes valve head warpage, just a few
thousandth of an inch is sufficient, and the cooling ability of the
valve head is diminished due to poor seating. 80% of a valve's cooling
is through the seat, reduce that and valve head temperatures will rise
to metal melting temperatures *in seconds*, especially at wide open
throttle. Compound that issue because, the valve head, now bent
slightly, will not seal and the combustion gases will be blowing through
the poor seat *as the combustion process occurs* adding greatly to the
heat load of the valve head. Note that the combustion processes are
normally complete by the time the exhaust valve opens. In fact, if the
engine is tuned for optimal performance, the mixture should be fully
burnt by 15-20 degrees ATDC. That means that when the valve opens under
*normal circumstances*, some combustion gas cooling has already occurred
and the valve head has lost some heat through the valve seat. If the
valve head is not sealing, then the combustion gases will be burning as
the gases are *leaking* past the valve seat.
>
> In the case of piston to valve clearance issues, you mostly see it on
> inlet valves as with big overlap cams like this engine ran the inlet
> valve begins opening very early while the piston is still moving up the
> bore towards top dead centre. As the two are moving towards each other
> interference can occur if clearances are not where they're supposed to
> be. In the case of exhaust valves it's a different story as the exhaust
> valve is moving *away* from the piston as the piston nears top dead
> centre, and as a result piston to valve contact with exhaust valves is
> quite rare. Not impossible, but certainly far less likely than it can be
> with inlet valves.
>
> However in either case the net result is usually the same in that unless
> you have things stupidly wrong about the most you'll ever see happen in
> the case of piston to valve contact near the very end (exhaust) or very
> beginning (inlet) of the valve's period is for the valve to bend
> slightly just behind the head, which will result in the valve no longer
> sealing against it's seat resulting in a loss of compression in that
> cylinder.
>
> And that is *not* what happened in the case of Les's engine.

With a slight leakage through the exhaust valve you get a double whammy,
combustion flame heating the valve and poor cooling of the head because
of the poor sealing.
>
> In Les's case the exhaust valve came into contact with the piston while
> the valve was at or near the fully open position, and there is basically
> only two ways for that to occur. Either the valve grabbed in it's guide,

Bullshit.

> or it "dropped" into the cylinder after losing a collet or had a collet
> groove failure which unloaded the valve spring. I never got to see the
> remains of the top half of the valve so I can't tell you exactly, and

So don't *invent* scenarios.

What you haven't allowed for here is valve *float* and valve
*overshoot*, both being candidates for contact with a piston. Valve
float occurs when the inertia of the valve when decelerating down the
cam is greater than the ability of the valve spring to keep the valve
(train) in contact with the cam. IOW, it stays open slightly more/longer
than it should at the high point and closing ramp of the cam. The head
of the valve is sticking further into the cylinder than it should at
that point. The other is valve overshoot. This occurs when the valve
reaches/passes the highest *acceleration* point and starts to go over
the top of the cam into the deceleration phase. The momentum of the
valve (train) keeps the valve moving on its opening path and, as a
result, the valve opens *more* than it would had it remained on the cam.
Both the scenarios, all other things being normal, only occur when the
engine is running at excessive RPM levels. This is most likely to occur
at WOT on a long downhill run. Guess what, that's where it *did happen*.

> while I wasn't at the track to see where Les was running his mixtures
> and have no idea how hot it was getting I'd happily bet that Les was
> running the thing fairly conservatively given that he had a habit of
> doing so and was familiar with the setup of the vehicle. Either the

Wouldn't matter what the mixtures were at had the valve head been given
a tap by the piston.

> valve guide clearance was too tight or the valve failed prematurely, but
> either way given that I had nothing to do with the head it had nothing
> to do with me.

You were doing the head fitting, everything to do with you.
>
> Some important points to bear in mind here are that a piston to valve
> clearance issue is a mechanical issue that is evident from the first
> time the engine is turned over in extreme cases, and certainly from the
> first time the engine reaches operating temperature in borderline cases.

Nope. Valve overshoot and valve float are *dynamic issues* and will
never occur when the engine is being rotated slowly by hand or operating
in a low RPM range.

> However in *all* cases it is *not* a problem that will suddenly
> magically appear after an engine has done some time at full noise like
> this one did, and if Clasener and and his clog wearing puppy dog had
> *any* idea at all they would *know* this.

Valve float and overshoot *only appear* when the engine is at full noise
or, more correctly, excessively high RPM levels.

Now, had you really done an auto machining apprenticeship, and studied
cam profiles, you would have learnt all about this and been able to
calculate when such RPM points occur. Certainly anyone who does
performance cam machining needs to be aware of cam profile limitations,
the effects of inertia, valve spring rates, etc. You appear only to have
the most simplistic idea of such matters. That tells me you *definitely*
never sat your arse in an auto machining apprentice class ever in your life.
>
> But apparently they did not. Or they did and ignored it and just
> invented whatever bullshit story they wanted to crow about, because hey
> it's not like they've never done that before, right?
>
> These people are fucking *imbeciles* who would be incapable of holding
> down a job for more than a day in any decent workshop where you had to
> reply on your skills and knowledge to get by....

My longest tenure was 20 years Darren. Would have been 30 had it not
been for sudden onset of illness. You?
>
>> You really need to get over your obsession with abusing Noddy. You're
>> not perfect yourself and anyone who saw the tractor split would agree.
>
> "Not perfect" is being extremely generous. Completely clueless would be
> more accurate.
>
>
And, again, it's a pleasure to see that I'm really getting under your
skin, you old faker you!

--
Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)