Originally Posted by sam-missle
Valve timing is valve timing, ignition timing is ignition. the dist. is driven off the cam gear only. you rotate the dist. around the driven shaft to set the ign. timing relative to TDC. Has nothing to do with valve timing. if that were the case millions of vehicles would have messed up ignitions, as most engines have timing chain or belt tensioners on them.
We are discussing moving (variable) cam timing in a RUNNING SBC engine by way of a chain tensioning device. If the tensioner advances the cam, this will advance the ignition timing too because they are geared together. Unless you have an idea for a variable distributor housing positioner that will counteract the variable timing chain tensioner, the timing IS going to change.