alright, i dunno if theres a thread that's already discussed this... but after searching, i couldn't find it...

anyways, is there such thing as advancing it too much? or is there a sweet spot for power/fuel econ?

now i'm not talking about advancing it so much that it starts pinging... but is there a point between when that starts happening and 0 degrees that is the best? (esp. for an astron) or do you advance it till it starts pinging and then back it off a little to stop it?

if ya could tell me, or direct me to info about how advancing work - i'd like to know... how does making it detonate before TDC help fuel econ and/or power?

and when the motor is pinging, it's the valve that's making the noise? if so, why do they?

cheers,
Bill

the pinging is the fuel/air mixture igniting too early, and it is acutally the noise that is caused by the ignited mixture hitting the top of the piston as it comes up.

ok, when you advance timing, you advance the point of spark in the revolution. the more you advance the more power, well in some cases not all. my safest bet is to advance it by a few degrees and then see but be warned USE ONLY PREMIUM if you dont and you get ****ty petrol and it doesnt ignite properly you could do some serious damage to your engine.

the pinging is the fuel/air mixture igniting too early, and it is acutally the noise that is caused by the ignited mixture hitting the top of the piston as it comes up.

Which in turn could bend your conrods and possibly crankshaft after a while running in these conditions. Not to mention various other damage caused to valves, piston & comp rings etc...

if you dont have a timing light, dont touch your timing.

the pinging which can be heard is well above the noise level of the pinging which is doing the damage aswell. and advancing timing doesn't really give much extra power anyway, maybe half a kw per degree, IF YOUR LUCKY

astrons have hot spots in the head too, i wouldn't touch ur timing mate.

ok, when you advance timing, you advance the point of spark in the revolution. the more you advance the more power, well in some cases not all. my safest bet is to advance it by a few degrees and then see but be warned USE ONLY PREMIUM if you dont and you get ****ty petrol and it doesnt ignite properly you could do some serious damage to your engine.

i use BP ultimate anyways... i get another 100km a tank with it + the throttle is much more responsive.

right now my timing is advanced a little more than what mitsu intended (done with a timing light)... i doesn't ping at all (even on unleaded)... i was curious if it's worth advancing it more to get better fuel econ or more power (i get 400km to a tank - with bp ultimate) provided i only run it off premium (which i do anyways)

you can advance timing too far like everyone else has said this leads to pining and does damage.
There is a sweet spot when timing the spark on an engine, this sweet spot is where the engine is timed to produce maximum torque. this is called torque timing, to set this the timing is adjusted on a dyno with the engine under full load at the rpm that produces peak torque. and the timing is adjusted to get the maximum torque reading on the dyno.
If a motor is predetonating (pinging) it will produce less than peak torque.
An engine that is timed correctly will be more thermally efficient and will produce more power burning less fuel, so u don't push the throttle as far to get enough pull to climb a hill etc and get better fuel economy.

When the fuel/air mix is ignited in a cylinder it doesn't just go bang, it burns, the most volitile molecules in the fuel are ignited first and they ignite the next most volitile molecules and so on till the fuel has burnt, the maximum amout of energy isn't released till about half way through the time it takes for this burn to occur. Timing is advanced to allow for the time delay in the energy release from the fuel/air mix so it isn't expanding over a piston that is already travelling downward and wasting the energy.
The aim is to ignite the fuel early enough to create full expansion over the piston at TDC, so the timing will be changed with engine rpm and load to achieve this(Vacuum and centrifical advance, or computer controlled advance.)

When a motor is pinging, it is the fuel air mix fully igniting before the piston has reached top dead centre, the ping or knock that can be heard is the sound of the piston hitting the side of the cylinder at supersonic speeds. this will quickly wear rings, pistons and cylinder walls and can shatter pistons, in worse case senarios as mentioned before it can also bend conrods.

Premium unleaded is a slightly more volitile fuel than ulp and is more stable as it burns, this allows for an engine to be run with more advance at peak torque and this will lift peak torque by a few Newtons. Premium also improves an engines thermal efficency and can improve fuel economy depending on how it's driven.

EFI 4cyl gen2 magnas are supposed to be timed at 13degs +/-2degs, with the single round check connector on the firewall LHS earthed (this turns off the computer spark advance and gives base timing mode).
I have found the the sweet spot in these Astrons on regular ULP is just under 15degs and that they start to predotonate over 15 degs in base mode (noticable as an intermittant miss at idle with the check connector not earthed). I would think you could advance slightly beyond 15degs if you were prepared to use only premium fuel.

keep an eye on your plugs if you insist on advancing the timing. If they have a white poweder on them it means your motor is running too hot and could be pinging, retard at once.

yeh my timming likes to change itself from time to time. its set to factory, then leave it for about 9mths and it retards itself a bit - i guess due to timming chain. my timming is advanced by + 3deg from factory setting, good enough and its noticable (you must run premium fuel - use bp ulitimate), could bump it up tad more but risky

you can do 1 of two things. get the car done by a mechanic or do it youself
if you have a timing light and r fairly confident of what your doing find the correct timing position and do it if not send it to a mechanic and get it done. there is ( and not wanting to step on anyones toes) another way to do this. Advance your timing and take the vehicle for a drive up a steep hill give max throttle and listen for the ping. if it doesnt ping advance it slightly further until it does,when you can clearly hear the pinging retard the timing as little as possible until you cant hear it any mopre , this will give you optimum timing position regardless of what the book says, this may take quite a few goes but if you cant hear the ping and any further advancement produces the ping then you have an optimun position and the most advance you can without damaging the engine. dont do this if your not confident of what your doing or if your not sure of what pinging sounds like because pre-ignition is a very damaging thing for an engine, thats y timing lights were made. dependant on what fuel u usually use this can change. Premium unleaded has a higher octane rating than the normal unleaded and due to this you can advance your timing further, so if you use premiun and time your engine to this dont go back to standard unleaded. Listen to Benau's words he knows what hes talking about, with a timing light just under 15 degrees before top dead centre.

i use BP ultimate anyways... i get another 100km a tank with it + the throttle is much more responsive.

Holy damn, Must just be my car where it doesn't respond to high octane fuels and CAI's.
:doubt: