I put a set of Zero gap rings in my 72 454 when I rebuilt it. Has anybody else had any experience with these rings? I have about 200 miles on my motor and I am noticing I am blowing smoke when I get off of the motor an then get back on it. I figure its valve seals. I used the stock type umbrella type seals. I have heard that the Zero gap rings create about 10% more compresions and create higher vacume and this might be sucking some oil in through the valve guides. I was wondering if I should have had pc seals installed instead of the umbrella seals? The motor runs strong but I used a quart of oil in the first 200 miles. I know things may seat themselves when the motor breaks in a little more. Should I just wait and see? Any ideas?