Ignition timing?

[xxspudxx]

Just curious really, with the car running i was turning the dizzy, and if i turned it one way the engine went to die, turn it the other and it would idle faster? Someone explain why and whats going on? lol, guessing thats to do with advance or retarding i think ive heard before? :thumb:

[gaznovalet]

wen you turn the dizzy your are advancing - retarding the timing dependant wich way you turn it. if too advanced you will risk detonation and loose power, and if too retarded you can end up with higher emisions, again lost power and unburnt fuel this is because the timing affects the air-fuel mix in the chambers on how its burnt dependant on where the piston is at.

[Guderian]

Unless you are setting the ignition up with the proper equipment (let's assume you have lost the original timing setting) on an old vauxhall you turn the dist. 'clockwise' (viewed from the nearside of the car) until you can detect a bit of detonation. Audible detonation will come in on a hot day, at low revs, in a high gear, uphill, or a combination of these situations!

You then back the ignition off slightly until the car cannot be provoked into detonation. Little bit of trial and error but within a week you should have a proper setting. Best done in hot summer as a summer setting will be fine all year round.

[garyc]

generally a std engine can take more advance, at low rpm the idle speed increases as you have seen. this will also advance at the top of the range which is OK up to a point. You will find the settings quite conservative so you could easily add a bit more. You will need a decent timing gun to do it. I doubt with std cr's you'll hit detonation, unless you had advanced the igntion way beyon optimum. Set it at std setting and if your that bothered take it to a rolling road.

[John]

what's the basic ign timing for a 1.2/3 then? 10 deg btdc?

[garyc]

std marks are 10 deg, without the vac advance connected.

Gary