Initial timing is the amount of advance the engine will have at idle speed and is determined by where rotationally the distributor is set to when the clamp is tightened down.The mechanical advance which is controlled by the springs and weights in the distributor,changes as the engine speed is increased this is what is referred to the advance curve.The amount of initial +the amount of maximum mechanical advance is referred to as total,and then you have vacuum advance also if your distributor is so equipped.The only time vacuum advance should come into play is at idle and part throttle cruise,under heavy throttle vacuum should be low enough so that there is no advance due to vacuum,thats where total advance is controlling your ignition timing.On most vintage v8's with slow burn combustion chambers optimum ignition timing under heavy throttle is typically 36-38 degrees ,since most factory initial timing specs are conservative at 6-8 degrees that means the mechanical advance needs to be able to give almost 30 degrees of advance to be optimal.Factory dist.seldom yield this much advance though, they typically will give 22-26 degrees and then not till higher than optimal RPM's(lazy curve).W engines lower advance requirements means you can expect see their mechanical advance yield somewhat lower than that with an equally lazy curve.So the amount of mechanical advance built into the distributor will allow you to get close to optimal total by increasing your initial,but you're still stuck with the lazy curve.Based on what you are saying about the run on and since what IMBVSUR said is absolutely right,I suspect your initial timing is set on the low side requiring your idle adjustment screw be set to far open to get the idle speed you want.As you increase your amount of initial timing your idle speed will increase and you will have to back off on you idle adjustment screw to get the idle back down,which may very well eliminate your run on issue.Your first step should be to set your initial timing somewhere above 10,preferrably 12-14,if hot starts show signs of the starter laboring or kicking back then its too far,get your idle speed set,and then start checking your amount of total advance using your timing light,check to see what the maximum amount is and see what RPM it takes to get it,this is where a dial back timing light will make things a lot easier because you should be out well past the end of your timing tab.Once you have this information,then you can start to figure what you need to do to get to optimum.If your distributor is of the vacuum advance variety make sure to disable it by pulling off the hose and plugging it while you do all of this.
cant go shoot rioters. My old dizzy has weights marked 37. Are these the stock weights ? They weigh 18.3 grams each. the springs were a combination of who knows what and a blue MSD spring so picked up a set of Moroso springs. Going to start with a medium and a light. Whatever was in there was only giving me 20 degres total at 2500. Glad I have time to play around with it.
