I was installing my old harmonic balancer earlier this evening and while torquing it on I was noticing that the rubber seal on the back of it (the seperation ring) was up against the timing cover. I thought there was supposed to be clearance between the balancer and the timing cover? I know the key is pretty much straight through and if I remember correctly the key on Ford motors has a stopper on it that keeps the balancer from going too far back. I moved over to a comp cams double roller timing chain, could the lower sprocket be thinner than the old one I had and letting it go back further?

Any thoughts on this would be appreciated.