Thread: Spark plug gap

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[QUOTE=thesals]not so much... the cam duration will change valve time but it wont change the electrical circuit,

Think abouty that statement for a minute. I agree a longer duration cam will definitely close the intake valve at a later time.... when the piston is further up the bore. Since the piston is furthur up the bore, what does this do to cylinder volume ? It decreases it because compression cannot happen untill the intake valve is shut. So with less volume of fuel air mix to compress the dynamic compression ratio is lower. Subsequently if you put a shorter duration camshaft in the dynamic compression ratio will be higher. So these pressure variations will have an effect on spark timing due to the density/ resistance to the compessed air at time of ignition. It will not be great but the variance is there.