[Excaliber]

Base timing is the 18 or so you have it set at now. As the rpm increases their are weights and springs just under the distributor ROTOR that begins to 'advance' the timing. Changing the springs (you could also change the weights) to a lighter weight spring makes the advance occur at an earlier rpm.

The vacuum advance should be disconnected and plugged to make sure it is NOT working when you set the base timing.

If this is a new MSD then it will NOT give you any mechanical advance until about 4000 rpm, unless it has all ready been modified (by changing to softer springs). There is also a little 'button' like thing that stops the mechanical advance from going TO far. Changing that 'button' moves the maximum allowed up or down the scale. Stock button should be fine, stock springs are NOT fine.

Detonation, ping, knock often mean the same thing. Detonation is the air\fuel ratio mixture 'igniting' either prematurly (to much advance) or in an uncontrolled (to fast) manner. This sudden pressure build-up of the fuel\air burning pushes the piston DOWN in the cylinder bore. THATS fundamentally how an engine works. IF the piston is still COMING UP and is not READY to GO DOWN and all that fuel\air burning pressure happens early, something is going to break! The piston will get extremely hot and actually start to break apart if it is severe OR prolonged detonation (ping, knock). Generally you can HEAR this "ping" sound and you know something is wrong. Cobra sidepipes are so loud you may not be able to hear it until it's to late. Detonation is common to high compression engines running low octane fuel. Higher octane inhibits detonation, thats WHY they make it and not all cars need it.

Timing is everything, it NEEDS to be set correctly some how.