Pinking
Posted By : Sam Hayes, 15-Aug-2005, 10:45pm
Pinking IS made worse by overadvancing the ignition, as it is the mixture getting too hot and igniting before it's all in the combustion chamber, so
you need to adjust the timing the other way (ie. retard it). This may, however, degrade the performance slightly, depending on how much you adjust it.
Also (I think) the lower the octane rating of the fuel, the more likely you are to get pinking, so you might want to put the timing back to 8 BTDC and
try using an octane booster additive and see what happens. I daresay someone else can offer far more (and probably more correct!) suggestions - I'd be
interested to hear, as I get occasional pinking.
Sam
Sam
Pinking
Posted By : Kevin Rochfort, 15-Aug-2005, 10:58pm
Robert,
You've made the "usual" mistake with advance and retard.
With unleaded fuel, you need to retard the ignition a couple of degrees, i.e. make the spark occur closer to TDC.
Assuming your engine is totally standard for a 1500, the figure in the book for good old leaded 98 octane fuel is 10 degrees before TDC set statically - i.e. with the engine OFF, and using a meter to measure the when the points just open. The factory manual also gives mechanical and vacuum advance figures for various engine speeds, but generally I find the static method to be the easiest to get correct.
For unleaded you should be running at about 7 to 8 degrees before TDC.
If you are getting pinking at low revs during acceleration, then it is also possible that you have the mixture set wrong, or the wrong oil in the dashpots - you should be using 20W50. It is also possible that someone has changed the needles, so the mixture profile is wrong.
Hope this helps.
Kevin
You've made the "usual" mistake with advance and retard.
With unleaded fuel, you need to retard the ignition a couple of degrees, i.e. make the spark occur closer to TDC.
Assuming your engine is totally standard for a 1500, the figure in the book for good old leaded 98 octane fuel is 10 degrees before TDC set statically - i.e. with the engine OFF, and using a meter to measure the when the points just open. The factory manual also gives mechanical and vacuum advance figures for various engine speeds, but generally I find the static method to be the easiest to get correct.
For unleaded you should be running at about 7 to 8 degrees before TDC.
If you are getting pinking at low revs during acceleration, then it is also possible that you have the mixture set wrong, or the wrong oil in the dashpots - you should be using 20W50. It is also possible that someone has changed the needles, so the mixture profile is wrong.
Hope this helps.
Kevin
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Pinking
Posted By : Nigel Gibbins, 16-Aug-2005, 07:07am
"For unleaded you should be running at about 7 to 8 degrees before TDC"
... unless of course you are using Optimax which is 98 RON in any case...
... ahh, the old mysteries of the timing set up
... just like the tyre pressure debate
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Pinking
Posted By : Chris Wilson, 16-Aug-2005, 08:40am
>>>>... unless of course you are using Optimax which is 98 RON in any case..<<<<<<
'Av you seen the price of Optimax lately?????? Bah - Humbug!!!!!!
On a different note - me garage gets delivered on 22nd - Wahooo!!
Regards-
Pinking
Posted By : Colin Wake, 16-Aug-2005, 10:48am
Have you seen the price of any petrol lately!!!
I was always told best way to set timing is to drive AT 30MPH in 4th gear ona flat level road and floor it.
You want very slight pinking initially.
Colin
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Pinking
Posted By : Mark Stradling, 16-Aug-2005, 11:39am
I had a few problems with pinking with my engine on super unleaded and Optimax. No problems running on BP Ultimate though, so this is what my baby is treated to in the main.
I keep a bit of STP octaine booster in the boot for those times all you can find is 95, and that seems to work too.
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