I was trying to avoid going too far and burying the OP with more than he was ready to read.
I mean no disrespect and am not trying to insult him. I will add though that Geoff is right....an engine with a more aggressive camshaft will respond a lot more favorably to additional timing advance.
Also, in the simplest way I can explain it, all Mopar distributors have a mechanism where as the engine speed increases, it slowly starts moving the point where the spark occurs
earlier and earlier in the combustion cycle.
This is called an advance curve because if you print out a graph of it, sometimes it looks like a curve like this:
Many distributors have an advance curve that totals as much as 28 degrees. This means if you are set to 5 degrees of advance at idle, as the engine speeds increase, eventually the distributor will add 28 degrees MORE for a total of 33 degrees of advance before top dead center.
Say you have a stock 318, a 383 maybe. At idle, the cylinders get a spark around 5-6 degrees before the pistons are at the top of the cylinders. As engine speeds increase, that spark needs to happen sooner since the pistons are moving faster.
That is advance.
Engines with aggressive camshafts are less efficient at idle than stock engines so they need more ignition advance at idle than a stock engine. Mine, for example has 19-20 degrees advance at idle.
