I read that you hear an engine ping when trying to set the timming... What is known as a ping?

Check the site below;it is a good start to understanding the reasons for certain sounds your engine may make.

http://en.wikipedia.org/wiki/Engine_knocking

Pinging is a rattle in the engine on acceleration, most common on hot days, if the timing is too far advanced or if you are using low octane fuel.
It means the air fuel mix is igniting prematurely, It is very bad for the engine.

There are two causes of pinging in an engine

Pre-ignition- This is caused by a hot spot in the combustion chamber that ignites the fuel/air mixture before the spark plug ignites the mixture. The Pinging sound is caused by the two wave fronts (spark plug explosion+hot spot explosion) meeting and the resulting expanding gases creating a frequency similar to the natural/resonate frequency of the metal around the combustion chamber creating a "pinging" sound.

Detonation- this is the spontaoonious ignitiion of the fuel air mixture before the spark plug ignites the mixture. It is caused by high combustion temps(high compression) and or too much combustion pressure(ignition advance+compression). Detonation is usually the one that puts holes in your pistons. The pinging sound is created the same way as above. It is from two pressure wave fronts meeting

also known as pink or pinking

Quote:
Never heard it called that befor....
A US term??

Lampy is pretty much on the money.

What must be realised first up is that the fuel/air charge in a combustion chamber, like the powder in a round of amunition, is supposed to be ignited, then burn progressively across the mass untill all of it is consumed. In a nornal condition, it does NOT explode.

When I went to tech we were taught that Detonation [also called ping, pinging & pinking] resulted when the fuel/air mixture was ignited, resulting in a normal flame front moving across the combustable mass, pushing a pressure wave in front of it. This effectively compressed the still unburned fuel charge untill it reached a point of spontanious combustion & this remaining charge literally explodes.
The resulting heat & shock wave in the combustion chamber does really nasty things to your pistons & rings.

This happens when the combustion is initiated [by whatever means] too soon for the octane rating of the fuel you are using. You May be using super-duper ultra high octane fuel, but if the combustion is initiated too soon, it will result in detonation.

Conversely, you can run low octane fuel in a high compression race engine, but to stop the detonation you will need to retard the spark so far that it might have trouble developing enough power to pull a used condom off your shriveled ........ never mind.

Low octane rated fuel is more volatile than high octane fuel. Low octane fuel simply burns faster, is more prone to detonate, & is best suited to lower compression engines while high octane fuel burns slower & is less prone to explode at high pressures in the combustion chamber, so is better suited to high compression engines.

The ignition process is initiated in one of two ways. If your engine is as it should be, all nice & clean in the combustion chamber, then the spark at the plug is the usual method. If you experience pinging, then reduce the throttle setting to reduce the compression pressure in the combustion chamber, or alternately, floor the throttle to kill the vacuum signal to the distributors vacuum advance canister & hopefully retard the spark enough to stop the detonation.
Finding the cause of the problem & rectifying it at the earliest possible moment is a must.

1. Is the octane rating of the fuel adequate?
2. Is the ignition timing correctly set & are there any problems with the distributor that allow uncontrolled movements with the advance curve. [no broken advance weight springs?]

Engines with high carbon buildup or excessively thin edges on exahust valves or 'other' can develop a glowing, almost white hot point in the combustion chamber [including the edge of the valve] that ignites the fuel before the spark plug fires.
This is pre ignition & can result in detonation, but is of itself, not detonation, just the initiating cause.

Two other causes.
If your engine has a working EGR system, make sure that it is not sucking air.
My 200B had a blocked pipe from exhaust to the EGR manifold which is bolted to the inlet manifold. This EGR manifold was made of alloy which had corroded through.
The blocked pipe prevented exhaust from leaking out but when the EGR valve opened in normal operation it sucked air into the inlet manifold resulting in a lean mixture that also lead to detonation.
I replaced the pipe from the exhaust & also replaced the EGR manifold with a cast iron one from a Bluebird & now everything works as it should.

Oil burning?
Oil has a VERY low octane rating & if present in sufficient quantities in the combustion chamber, it can detonate, or it can dilute your low octane fuel enough to initiate detonation.
Additionally, it builds up carbon deposits which can provide the hot spot that causes pre ignition & subsequent detonation.

EDIT DatJaffa.
Pinking is a dreadfully British term old chap.

Jesus Christ Dodgeman You need your
own segment "Ask Dodgey"
Quote:Also "Not enough power to pull grandpa off
grandma"

Edit: the other half of pong?

You learn something new every day

Dam Brits think they run the world!!!

dodgeman is exactly right. I should have been more clear.
explosion was a bad term to use. The combustion process takes "time" An insantanious explosion would cause our engines to be blown into shrapnel.
The mixture is ignited and the flamefront expands out