[QUOTE="Steve"] Steve wrote: u who don't understand the concepts. Ouch, In my earlier haste I completely mis-stated this. A stretching chain or belt can never advance the *average* timing of the cam, only retard it. Without damping, there can be excursions of advance and retard, but since the cam on AVERAGE is being dragged along by the crank, it will lag behind the crank (retard) to whatever extent it is allowed to do so by the cam drive.[/QUOTE] you should have bothered to look that up earlier before shooting your mouth off. [QUOTE] The drawback to putting a tensioner on the taut side is that as the cam drive (be it chain or belt) stretches, the added slack will be accumulated BETWEEN the crank and cam, maximizing the amount of retard by the total stretch of the belt or chain. OTOH, if you tension on the slack-side, the retard is minimized because all the extra length is carried harmlessly on the slack side,[/QUOTE] rubbish - read the next chapter. the only stretch that matters is that between the crank and the cam, the tight side. the rest of it can take an excursion back up through the drivers side door column, around the trunk and back down the local high street for all it matters to cam timing. [QUOTE] and the only retard experienced is the delta-length of JUST the length of belt or chain on the taut side at any instant, which is necessarily less than 1/2 the total amount of stretch.[/QUOTE] 1, it's not a derivative so any "instant" thing is a red herring. 2. see above for relevance of the slack side. bottom line, don't blow smoke up my kilt steve - i hate seeing grown men grovel on their knees.