Ok Ralfy I'll give you timing 101.. Timing is just THAT! TIME IS WHAT IT IS ALL ABOUT.. The TIME it takes for all (or most anyway) of the fuel to burn. Since the burn TIME is static and NEVER changes as the engine speed builds the TIME the fire is started needs to be earlier and earlier.. This in order to keep the burn while the exhaust valve is still closed.. You must understand that as the engine speed increases it takes LESS time for the piston to make the trip DOWN under the power of the burning fuel.. Now once that is fully understood it is a simple matter to get timing ADVANCE into ones noodle.

To start the timing at IDLE needs to be ..whatever the factory sez.. Most engines at idle take from 4* to 8* advance.. OF COURSE this advance depends entirely on the rpm at idle and the length of the stroke.. All of which contribute to the TIME of which the burning will take place.

NEXT as the engine needs more advance the MECHANICAL timing comes into play which makes the timing increase at certain rpm depending on which length of stroke that particular engine has.. THIS timing is static and usually shouldn't be messed with..

THEN we have the vacuum advance.. This advance depends on how wide open the throttle is.. IF the throttle is WIDE OPEN the spark will start the fire and the fire will JUMP OUT of the carburetor if this timing occurs.. SO this amount of timing is connected to the vacuum which drops off as the throttle is opened. As the vacuum increases the timing begins to advance with the increased rpm's. So at certain rpm's ALL the timing is working as the vac is sufficient to keep the timing increased.

The neatest thing for a newbie to do is to make some EXTRA marks on the damper and put a light on and then increase the engine speed and WATCH all the timing come into play.
As the engine speed is slowly increased the mechanical will slowly open and the newbie will be able to watch it happen.
Then put the vac hose on the dist and watch as the engine is quickly revved..the timing will DROP and then get back to full advance..
But one needs some extra chalk marks on the damper to see this well. I advise marks at 10* 15* 20* 25* and 30* I even paint my dampers with different colors of paint to make the timing more evident.

I hope this helps.. Try to remember the timing in question here is really TIME! The time it takes to burn the fuel.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />