Advice on pinking
Discussion
No pinking is acceptable. It is pre-detonation, which means that the fule is being ignited whilst the [oston is still on the way up. The noise you can hear is the piston being knocked back. You will also be creating hot spots which may lead to holed pistons, burnt out valve seats, etc.
Fine if it only does it when you nail the throttle, then don't nail the throttle, but you must get it seen to.
It may be too low an octane rating on the fuel, too high a compression, too advanced ignition timing, carbon build up on the piston crowns (raising compression) etc.
Fine if it only does it when you nail the throttle, then don't nail the throttle, but you must get it seen to.
It may be too low an octane rating on the fuel, too high a compression, too advanced ignition timing, carbon build up on the piston crowns (raising compression) etc.
Moto said:
Anyone got any advice on how much pinking is acceptable. I only get it when nailing the throttle. I've had advice from a race mechanic that it's not a problem but have from others that it's not good and I should retard the timing.
Views from anyone else ?
It's not good and you don't want it.....Really!
It can turn your pistons into cylinders: looking through the spark plug hole and seeing a big-end is somewhat alarming
. Draining out piston crowns from the sump is not cool (been there, done that). Don't follow me on this one! Moto said:
Anyone got any advice on how much pinking is acceptable. I only get it when nailing the throttle. I've had advice from a race mechanic that it's not a problem but have from others that it's not good and I should retard the timing.
Views from anyone else ?
The good old Rover V8 uses mechanical centrifugal advance built into the dissy. Over time, the springs which restrain the weights will stretch and allow too much initial advance, often causing pinking. To perform a crude test for this, take the dissy cap off and try and turn the rotor arm in one direction and then the other direction. If there is any slack in the springs, you will immediately feel it. The cure is to either replace the springs (if you can get them) or very carefully bend the mounting posts to take up the slack. You will need to check the base timing after this, but it does work if the springs are the cause of the problem. Oddly, this is something most mechanics have never heard of, perhaps because so few cars on the road have centrifugal advance in these high tech times.
I have a feeling that the centrifugal advance is engine SPEED dependant, not LOAD dependent. Pinking occurs when you increase the load by nailing the throttle i.e. before the engine speed picks up. So I suspect that the centifugal mechanism is not the first thing to suspect - unless I'm missing a subtle point?
Steve
Steve
red griff 500 said:
I have a feeling that the centrifugal advance is engine SPEED dependant, not LOAD dependent. Pinking occurs when you increase the load by nailing the throttle i.e. before the engine speed picks up. So I suspect that the centifugal mechanism is not the first thing to suspect - unless I'm missing a subtle point?
Steve
You are correct, it is speed dependant. If the springs are slack, there is too much centrifugal advance at low(ish) RPM. When you apply load by opening the throttle, pinking will then occur. If you have genuine pinking at light throttle, then there is something really seriously wrong.
Steve
when i bought mine the ignition timing had been retarded a few degrees , I got it of a guy pushing 70 who found it to quick for him and allso retarding the timing ment he could run on normal unleaded fuel,so i had the timing advanced back to standard ,the dealer said I would not notice the difference in the power you would expect to come from advancing the timing and he was correct ,the point I am trying to make is if you are running on optimax fuel and it is still pinking just get your timing retarded to stop it and you will not notice any drop in power , I would be very wary of long term pinking ,hope this is of some help regards Steve.
when i bought mine the ignition timing had been retarded a few degrees , I got it of a guy pushing 70 who found it to quick for him and allso retarding the timing ment he could run on normal unleaded fuel,so i had the timing advanced back to standard ,the dealer said I would not notice the difference in the power you would expect to come from advancing the timing and he was correct ,the point I am trying to make is if you are running on optimax fuel and it is still pinking just get your timing retarded to stop it and you will not notice any drop in power , I would be very wary of long term pinking ,hope this is of some help regards Steve.
steve290353 said:
Steve
when i bought mine the ignition timing had been retarded a few degrees , I got it of a guy pushing 70 who found it to quick for him and allso retarding the timing ment he could run on normal unleaded fuel,so i had the timing advanced back to standard ,the dealer said I would not notice the difference in the power you would expect to come from advancing the timing and he was correct ,the point I am trying to make is if you are running on optimax fuel and it is still pinking just get your timing retarded to stop it and you will not notice any drop in power , I would be very wary of long term pinking ,hope this is of some help regards Steve.
Retarding the ignition is only masking the problem, so is not the ideal solution. In my experience, working as a Hometune technician, the Rover V8 (admittedly in Rovers, not TVRs) is unusually sensitive to retarded ignition, causing a very noticeable power loss. Perhaps TVRs have so much surplus power you don't notice losing some. I would have thought that you would want the most you could get out of it though, which means having it set up right.
Paul.
Hoover33 said:
What does "pinking" sound like......
mine makes a noise when nailing it around 5000 revs, but it sounds like loose baffles ... (well thats my daignoses.... similar sound to my Atra GTE loose baffles many years ago)
Just wondering
Must get it booked in for a once over
Pinking on the Griff sounds just like something has come loose abou mid way on the exhaust.
At least thats how it sounded on mine when it was doing it whilst driving.
As I understand it, the amount you need to retard by to cope with lower octane ratings (97->95 etc) is very small (1-2 degrees) and makes very little difference to the power, this is also offset by the fact that the lower octane fuel apparently burns faster (I don't see why either, just repeating what I have read on PH). I think that knocking the timing back a degree or so to prevent pinking is a good idea, obviously not a good idea to retard it any further than you need to though.
.... in at Offords getting sorted as I speak .. so should be 
as well as sports exhaust conversion 
B16 RFF said:
I have a feeling that the centrifugal advance is engine SPEED dependant, not LOAD dependent. Pinking occurs when you increase the load by nailing the throttle i.e. before the engine speed picks up. So I suspect that the centifugal mechanism is not the first thing to suspect - unless I'm missing a subtle point?
Steve
You are correct, it is speed dependant. If the springs are slack, there is too much centrifugal advance at low(ish) RPM. When you apply load by opening the throttle, pinking will then occur. If you have genuine pinking at light throttle, then there is something really seriously wrong.
Thanks for the clarification B16RFF - very interesting!
red griff 500 said:
red griff 500 said:
I have a feeling that the centrifugal advance is engine SPEED dependant, not LOAD dependent. Pinking occurs when you increase the load by nailing the throttle i.e. before the engine speed picks up. So I suspect that the centifugal mechanism is not the first thing to suspect - unless I'm missing a subtle point?
Steve
You are correct, it is speed dependant. If the springs are slack, there is too much centrifugal advance at low(ish) RPM. When you apply load by opening the throttle, pinking will then occur. If you have genuine pinking at light throttle, then there is something really seriously wrong.
Thanks for the clarification B16RFF - very interesting!
Yes it is, isn't it? It's something I was taught whilst training to be a Hometune technician, but I've never seen it mentioned elsewhere.
Paul.
Moto - I see you have a Griff 500. The most common cause of pinking on the 500 engine (in my experience) is actually a lean mixture, or an injector problem.
Lots of cars come in with only 21-22 Degrees max advance, measured at 4000RPM with the vacuum line disconnected. This is always to stop them pinking. When they're happy they usually like nearer 28-31 Degrees.
Injector problems cause pinking by producing a poor spray pattern. If the fuel jet is not atomised properly, it appears to be a lean mixture to the affected cylinder. If you look at the spark plugs after a good hard run, any with especially clean ceramic electrode noses are signs of this problem. The large droplets of fuel scour the nose of the plug to make it very clean!
With an experienced ear you can tell if it is just one cylinder, or the whole lot.
One way or another, you need to get it sorted!
Lots of cars come in with only 21-22 Degrees max advance, measured at 4000RPM with the vacuum line disconnected. This is always to stop them pinking. When they're happy they usually like nearer 28-31 Degrees.
Injector problems cause pinking by producing a poor spray pattern. If the fuel jet is not atomised properly, it appears to be a lean mixture to the affected cylinder. If you look at the spark plugs after a good hard run, any with especially clean ceramic electrode noses are signs of this problem. The large droplets of fuel scour the nose of the plug to make it very clean!
With an experienced ear you can tell if it is just one cylinder, or the whole lot.
One way or another, you need to get it sorted!
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