What is pinking?

Never got my head around this?

Is it something to do with spark plugs?

 

It is a secondary ignition, caused by compression, remote from the
sparkplug. If for instance the timing is set too advanced, then the peak
pressure in the cylinder can exceed the normal limits and you get
compression ignition occuring (like in a diesel engine) when it shouldn't.
Can also be caused by wrong grade of fuel, or excessive throttle opening at
low engine speed for instance.

Did a lot of work on this on a Ricardo E6 experimental engine many moons
ago....... ah... those were the days........

 

Not really.
It's pre-ignition of fuel in the cylinder, that is ignition before the spark
lights it up, and of course being at the wrong place (before the piston
reaches top dead centre) it puts an awfull stress on the
piston/con-rod/crankshaft and gives a distictive knock noise.
It's diesel-like detonation usually caused by using a lower grade of fuel
than that recommended for the compression ratio of the engine.
As previously stated extremely advanced ignition timing will also give this
symptom.

Rick.

 

another description as follows:
under normal conditions the spark will ignite the fuel just before the
piston reaches top dead centre, this is done to account for the time it
takes for the fuel to explode and force the piston away, by the time this
happens the piston should be just past top dead centre and this is what
keeps the engine running.
pinking is what happens when the fuel is ignited too early and instead of
forcing the piston away in the direction the engine is turning, it tries to
turn the engine the opposite way since the piston hasnt reached top dead
centre yet.
of course it wont ever manage to turn in the opposite direction, the force
is minimal and the momentum of the engine far exceeds this, however it does
cause a knock which you can hear as a tinny rattle (pinking)
this is cause when the ignition timing is too far advanced, also when you
accelerate the vacuum unit on the distributor is advancing the timing even
more so as is the centrifugal advance system, so with this in mind the
timing has to be set up just right to prevent all this.
steve.

 

Subject: Re: What is pinking?

None of the above has anything to do with pinking

No it isn't. The timing retards at high throttle openings.


Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
I'm not at all sure why women like men. We're argumentative, childish,
unsociable and extremely unappealing naked. I'm quite grateful they do though.

 

Apart from the comments in earlier postings, also note:
Many modern cars with computerised Engine Control Units (ECUs) have sensors
stuck on the engine specially to detect "pinking". If they "hear" it
happening, they automatically adjust the ignition timing to eliminate it,
sometimes on a cylinder-by-cylinder basis. In this way, optimum ignition
timing can be achieved even for varying grades of fuel.

- Steve

 

it is exactly what pinking is, actually, i have described how it happens and
perhaps if your not fammiliar with the concept then you don't understand it.

no it doesnt, actually it has nothing to do with throttle position, it is
related to either engine speed, (in which case the centrifugal advance (if
fitted) advances the timing)) or engine load, in which case the deppression
in the inlet manifold will cause the vacuum on the distributor to advance.
nothing retards the timing, except when already advanced by one of the above
and its returning to its original position.

 

Subject: Re: What is pinking?

LOL. This is another of those "do you realise who I am sonny?" moments. Read
some of the website or a good book like "The Internal Combustion Engine in
Theory and Practice" by C.F.Taylor before you start arguing with the experts.
Pinking, as with any other psuedonym for detonation, is the sound of pressure
waves in the combustion chamber caused by pockets of fuel/air mixture auto
igniting due to excess temperature and pressure before the spark ignited flame
front gets to it. Read the post by John Ricketts who has actually worked on the
subject.

It has nothing to do with combustion trying to push the piston back down the
way it came or any of your other nonsense.

Struth. A vacuum advance unit advances the ignition timing when the pressure in
the inlet manifold is low (small throttle openings) and retards it again when
inlet manifold pressure is high (large throttle openings). It doesn't, and I
quote

when you
It's the exact opposite of that.


Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
I'm not at all sure why women like men. We're argumentative, childish,
unsociable and extremely unappealing naked. I'm quite grateful they do though.

 

are you trying to be clever, because reading a pathetic web sites
description and actually knowing due to 25 years of experience are 2
different things.
i wont even bother to explain why you are wrong, you sound to me like some
teenager who's read too many books but this isn't a slagging match, i know
the difference and thats all that matters,
what i do object to though is the original poster being fed immature
opinions instead of the answer to his question.
do your homework before posting in future.
i bet you haven't even worked in cars with "proper distributors"
modern cars don't have the same problems.

though.

 

Subject: Re: What is pinking?

I meant my website then you'll know who I am and what I do.

I strongly suggest you read up on what detonation is and also how vacuum
advance systems work. It isn't an uncommon mistake for people to think they
work the opposite way round to how they actually do. If you don't wish to learn
though then by all means keep your head firmly buried in the sand.

As to "proper distributers" I've been setting them up since the 70s but it
makes no difference if the timing under load is set by a vacuum advance unit or
an ECU map. More advance is needed at low load and low throttle openings and
less advance at high load and high throttle openings. If you understood how
flame speed varies as the amount of mixture in the cylinder varies then it
would become obvious and you wouldn't keep arguing an indefensible position.


Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
I'm not at all sure why women like men. We're argumentative, childish,
unsociable and extremely unappealing naked. I'm quite grateful they do though.

 

position.

So you're saying it's nothing at all to do with cross-dressers wearing rouge
when out on a date? <g>

Rick.

..

 

don't care who you are, or what you do, completely irrelevent in this
discussion.

self explanitory, "vacuum advance" what do YOU think it does, make the tea
?????
have a close look dipstick, just for the record, mechanical diaphram
connected directly to a cam system fixed to the distributor shaft.which
suprisingly enough "advances the timing" at different levels depending on
manifold depression.

MAP sensors do the same think dipshit, they read manifold pressure via
vacuum pipes.

More advance is needed at low load and low throttle openings and

?????????????????????????
low load and low throttle position would indicate an idle condition or
similar, and YOU think this requires more advance ?????? fu*k me your funny.
completely inacurate, but funny.

how about you explain why centrifugal advance, a mechanical cam device,
relies simply and only on engine speed to advance the timing, if your
confused as to which way it operates then perhaps you need a career change.
McDonalds are hiring in our area.

though.

 

I don't see


first you state that pinking is a spontaneous combustion of fuel
before the spark should do.
Now you say engine's can detect that, and, by adjust the ignition
timing correct it.

Given your earlier porting this is not something you could correct by
timing as your car runs like a diesel and does not need spark plug at
all.

Perhaps you can enlighten me. because i'm a diesel driver and could
wel benefit from sparkplugs then.

 

Subject: Re: What is pinking?

I see. So the fact that I design race engines and consult on, amongst other
things, ignition systems and calibration is irrelevant to such a discussion is
it? It's been a while since I came across someone on Usenet quite so prepared
to pontificate on a subject without understanding it or so unwilling to listen
and learn. They do say of course that arguing with an idiot makes you one too
but hopefully someone following this thread will learn something from it.

Quite correct. It just works the opposite way to that which you think.

It's really very simple grasshopper. Do try and pay attention if your mind
isn't completely closed. The amount of ignition advance depends on the burn
time of the fuel/air mixture. At a given engine speed, the longer this takes
the earlier the spark has to fire if the mixture is to be fully alight by TDC.
I trust this bit is self explanatory.

One of the biggest influences on burn speed is the amount of mixture in the
cylinder. The more completely filled the combustion chamber is the faster the
flame travels. This is because the more tightly packed the fuel/air molecules
are the easier it is for the flame front to spread from molecule to molecule
and traverse the combustion chamber. It's also influenced by the amount of
residual burnt gases from the previous cycle which inhibit the flame as they
are not combustible having already burned. Residual contamination is high at
low throttle openings and vice versa. At full throttle the residual gases are
flushed out more fully into the exhaust system by the incoming charge.

The conclusions should now be obvious. At low throttle (idle, cruise etc) the
combustion chamber is only partly filled, residual contamination is high and
burn speed is low. More advance is required to get the mixture alight by TDC.
The vacuum advance canister achieves this by sensing the high depression in the
inlet manifold and advancing the distributor. As the throttle opens more fully
the inlet manifold pressure increases closer to atmospheric and the amount of
advance is decreased again. At full throttle the vacuum advance falls to zero
and only the centrifugal advance is determining the spark timing.

Please try and understand what inlet manifold depression is. The pressure in it
is lower when the engine is "sucking" against a closed throttle. It's higher
when the throttle is open and directly connecting the manifold to atmosphere
via the carb. Vacuum isn't something that happens when the throttle is open -
it's the opposite.


Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
I'm not at all sure why women like men. We're argumentative, childish,
unsociable and extremely unappealing naked. I'm quite grateful they do though.

 

Hello Dave,

I'm reading this post with interrest since its beginning, and I'd like to
ask you something...

Pinking is a kind of strain combustion, i.e an inadequate one, responsible
for bad performance among other things (and I hope you get what I mean
accross my unperfect english), right ?

In case of pinking, the ignition advance must be reduced, right ?
And now, more hardware : pinking causes an acoustic noise change, isn't it ?
May an ECU detect it through a resonator ? I've heard of pinking sensors

 

this is called a "knock sensor" but don't bother trying to explain it to mr
baker, he might throw some book at you and write a chapter on it.
(wonder if he has a brother called danny?)

i never said that...........i would called that "pre-ignition"
i think mr bollox for brains baker said that.

that i agree with, but not many manufacturers have sucessfully incooperated
it into a management system.
rovers sytem for example was a disaster.

who's car runs like a diesel??? and maybe if we could perfect pre-ignition
then hey, we might just be able to do away with spark plugs, but your
bordering on mr bakers territory there.

nope because diesel relies on compression to ignite, not an introduced
spark.



hope your learning mr baker.

 

big hairy bollox..............the amount of ignition advance on a standard
distributor with both vacuum and centrifugal advance systems depends on the
speed of the distributor and nothing else whatsoever for the centrifugal
advance........(argue that point and your a tosser) and manifold pressure in
the inlet manifold (which is where the vacuum advance system takes its
vacuum from...duh) and that pressure in the manifold will depend on throttle
position related to engine speed.....if your still unsure at which points a
manifold will have maximum vacuum then try fitting a vacuum guage to one of
your toy cars that keep rabbiting on about.
by the way..............grasshopper???? you been watching too many karate
kid movies..........

this has absolutely nothing whatsoever to do with ignition advance or
retard.
..

TDC.

more big hairy bollox........if you need more evidence then try
this.....connect your timing light and see what happens to the timing at
different engine conditions...then come back and post...at low speed and
idle the timing is more or less the same as static set timing (you are still
with me right???)
accelerate and watch what happens to the timing mark...........

you twat.........if thats the case then how do you expect a venturi to
work..............

though.

 

rovers in general are a disaster.
I just don't see, folowing your theory of early combustion, how you
can correct pinking by introducing a spark in the first place (
because the damn fuel is already burning) and, giving tha variable
timing of it when this spark should be introduced to the feul mixture

My car runs like a diesel, it is one.

it was said in a retorical way, I know a thing or two about diesel
engines...

 

Why don't you blokes enjoy your exchange of insults by email? This
started off as an interesting thread until.... I have yet to see an
abusive post anywhere, or a response to such a post, which does
anything to advance humanity or knowledge.

 

you dont correct pinking by introducing a spark, the spark is already there,
the reason pinking happens is because the spark cuts in at the wrong time,
ie: too early.

mmmmmmm...not easy to emphasise sarcasm in a line of text.