Pete Lewis Posted June 1, 2019 Report Share Posted June 1, 2019 Have you elliminated the accuspark yet Pete Link to comment Share on other sites More sharing options...
Paul H Posted June 1, 2019 Author Report Share Posted June 1, 2019 1 hour ago, Pete Lewis said: Have you elliminated the accuspark yet Pete Hi Pete, plan is to retard timing to the white mark first as this is the easiest thing to do Regards Link to comment Share on other sites More sharing options...
Paul H Posted June 2, 2019 Author Report Share Posted June 2, 2019 On 31/05/2019 at 12:27, johny said: I see in the original post the timing is 'set 2 - 3 degrees more advanced than the white line' and I wonder why this is? Presumibly the white line was marked by the previous owner to indicate the standard timing position to use a strobe and if correct I cant see that it should ever be set more advanced than that. Normally you set the timing to this point and then retard it progressively to get any knocking to an acceptable level.... Hi Johny reset the timing to the white marks as you suggested and I’ve got my Vitesse back , went up the hill no issues at 55 mph no hesitancy. So I had set the timing too far advanced so what was happening in the engine to cause the hesitancy . Was the engine firing before it should ? Thanks again I can now enjoy 😊 the car again Nb using Tesco Momentum Paul Link to comment Share on other sites More sharing options...
johny Posted June 2, 2019 Report Share Posted June 2, 2019 Result! Cant explain exactly why too advanced did that except the timing is set up so that the explosion starts before TDC and allows enough time for the combustion to produce the maximum pressure just at the right moment ie. after TDC. If you now have pinking (knocking) the mixture is igniting in another area of the combustion chamber because its too explosive and being set off by the pressure wave from the initial spark induced ignition. The best solution is to decrease the ignitability of the fuel by increasing its octane or a poorer alternative is to reduce the advance of the igntion timing.... 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 2, 2019 Report Share Posted June 2, 2019 yes excess advance is going to try and run it sort of ..........backwards in simpluze, the amount of advance is determined by how long it takes to get the burn to go bang, so its fired to coincide with matching the piston is about to go down if you pop it well before this time the piston and the energy is lost trying to fight a piston coming up on compression rather than just in time to send it down the stroke the worse the burn the more the advance , but then it causes pinking as it burns and try's to destroy the piston so nasty fuel then has to be retarded and you loose performance Pete 1 Link to comment Share on other sites More sharing options...
Paul H Posted June 2, 2019 Author Report Share Posted June 2, 2019 That’s Pete and Johny for the explanation. So my description “hesitancy “ was knocking ? Are knocking and pinking the same thing ? Great forum this 😄 Paul Link to comment Share on other sites More sharing options...
NonMember Posted June 2, 2019 Report Share Posted June 2, 2019 No, hesitancy is not the same as knock, nor caused by it. It's a bit more complex. As Johny said, the optimum timing is such that the mixture burns to its maximum pressure just at the point where the piston needs maximum acceleration. That's well before its most efficient point (mechanical advantage means that occurs half way down the stroke) but if you over-advance then you get that peak pressure while the piston is still rising, and it actually works against the engine, as Pete said. If you were to plot, for a given engine speed and throttle opening, the power output against ignition advance, the curve has a (fairly broad) peak. It's normal to define a central part of that peak as "about flat" and define the most retarded end of that "flat" as being "minimum advance for best torque", or MABT. That's where you would run the engine if you didn't have to worry about knock. In reality, if you were to run at MABT down at idle, the air flow would be so small that it would get unstable. So the factory set up the advance curve to allow for slightly poorer idle advance, and bring it back to MABT at higher speeds. That's why the "peak idle speed" method of setting the advance has a "then retard it a little" step. Normally, people say this is to avoid knock, and often it is, but for some operating conditions, forgetting to retard it means you're now running over-advanced. Pinking and knocking are often used interchangeably. They refer to the same effect (explosive ignition of some part of the mixture) which can sound different depending how bad it is - from a light tinkling "pink" to a heavy knock. There is a distinction between "normal knock", which as Johny correctly said is "set off by the pressure wave" from the real ignition, and "dieseling" pre-ignition, which can happen if you've got serious hot spots and over-rich mixtures, even without a spark, and leads to running on. There is also the issue that the speed of the burn is dependent on the fuel chemistry. Back in the late 1990s, Shell briefly introduced a high-efficiency fuel that destroyed a lot of engines because it burned faster than normal fuel. Had the engines been set up for that fuel, it would have given a more efficient burn and better emissions and economy, but since they weren't, it caused terminal knock. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 2, 2019 Report Share Posted June 2, 2019 Shell with ICA if i remember it ignition control addative caused a few ka...booms think vauxhalls suffered badly from it pete Link to comment Share on other sites More sharing options...
johny Posted June 2, 2019 Report Share Posted June 2, 2019 30 minutes ago, Paul H said: That’s Pete and Johny for the explanation. So my description “hesitancy “ was knocking ? Are knocking and pinking the same thing ? Great forum this 😄 Paul If I remember right your hesitancy was produced at higher speeds whereas knocking/pinking tends to be worst when accelerating at low revs in a high gear. I think its a really noticeable sound but some people seem to find it hard to diagnose perhaps mistaking it for something mechanical..... Link to comment Share on other sites More sharing options...
Badwolf Posted June 2, 2019 Report Share Posted June 2, 2019 Ignorrant question coming up... can someone please describe 'pinking' and why it us called that. Link to comment Share on other sites More sharing options...
Paul H Posted June 2, 2019 Author Report Share Posted June 2, 2019 34 minutes ago, johny said: If I remember right your hesitancy was produced at higher speeds whereas knocking/pinking tends to be worst when accelerating at low revs in a high gear. I think its a really noticeable sound but some people seem to find it hard to diagnose perhaps mistaking it for something mechanical..... Correct accelerating through the gears no issue , my hesitancy issue was when the Vitesse was under load ie accelerating going up a hill . Toddling along at 40 mph on the flat no issues Paul Link to comment Share on other sites More sharing options...
johny Posted June 2, 2019 Report Share Posted June 2, 2019 Ive heard it called knocking, pinging and pinking (think the last one is just a derivation of the previous) and theyre just names that try to describe the noise it produces. Our engines will always do it at some point and its perfectly acceptable as long as its not excessive. The criteria I use is that in 4th gear on the flat if I floor the accelerator the engine will pink (rattling/tinkling that sounds quite mechanical) until I reach 2000rpm when it should stop. If its produced at any other time somethings wrong and you risk damaging the engine so, as I say, if everthing else is correct with the engine the two options are to increase fuel octane or reduce timing advance. Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 2, 2019 Report Share Posted June 2, 2019 27 minutes ago, Badwolf said: can someone please describe 'pinking' and why it us called that. My mother has pinking shears, what's that all about? Doug Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 2, 2019 Report Share Posted June 2, 2019 Doug try them on your haircut !!! /\/\/\/\/\/\/\/\ and on advance you can add that the extra pressure can make plugs break down and that gives you some good hic ups Pete Link to comment Share on other sites More sharing options...
daverclasper Posted June 2, 2019 Report Share Posted June 2, 2019 Glad you sorted it and an easy fix, It's kind of disillusioning when you can't trace an issues, wondering is it something bad going on here (well I do, as a bit of a half empty person, unfortunately). My mum had hefty pinking scissors (as a kid, I was a bit fascinated by them for some strange reason) , back from the time when folk used to DIY and repair things more. I guess a lot of stuff, relatively cheaper now. Dave Link to comment Share on other sites More sharing options...
daverclasper Posted June 2, 2019 Report Share Posted June 2, 2019 3 minutes ago, Pete Lewis said: Doug try them on your haircut !!! /\/\/\/\/\/\/\/\ Good for the old feather cuts, back in the 70's Dave Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 2, 2019 Report Share Posted June 2, 2019 As described the shears give a ragged cut just like the edge of a carnation. Carnations are also known as pinks. So, pinking shears. And ragged is the way your engine runs when it's pinking! So named by a gardening mechanic in the olden times, probably Pete, he's always down the garden centre. Doug Link to comment Share on other sites More sharing options...
JohnD Posted June 2, 2019 Report Share Posted June 2, 2019 No idea about the derivation of the "pinking shears", but they are nothing to do with engie pre-ignition. It's an old descriptive term for a sudden, high-pitched noise. The alarm calls of some birds are decsribed as 'pinking', eg the Chaffinch See Hear what I mean? Think also of "ping", which is used across t'Pond for the same thing. John Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 2, 2019 Report Share Posted June 2, 2019 19 minutes ago, JohnD said: It's an old descriptive term for a sudden, high-pitched noise. Ok, so the next time I walk on the cat's paw, I'll know she's just pinking. I'd have called it screaming, meself.... 1 Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 2, 2019 Report Share Posted June 2, 2019 2 hours ago, JohnD said: No idea about the derivation of the "pinking shears", but they are nothing to do with engie pre-ignition. Are you sure? I've just ordered a pair. Doug Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 2, 2019 Report Share Posted June 2, 2019 Think fhe chaffinch needs retardiing I liken pinking as a tin can with some marbles rattling around Pete Link to comment Share on other sites More sharing options...
JohnD Posted June 2, 2019 Report Share Posted June 2, 2019 Colin, I said BIRDS, not cats! doug, a two engined GT6 would be something else! Pete, You say marbkes, I say chaffinches, let's call the whole thing off! John Link to comment Share on other sites More sharing options...
dave.vitesse Posted June 2, 2019 Report Share Posted June 2, 2019 Pinking can happen on the Mk2 at half throttle on a hill. The main cause is the vacuum advance. To test this out disconnect the vacuum pipe, block up the carb end to stop air getting and do a test drive. Dave Link to comment Share on other sites More sharing options...
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