Your right. When I changed over from a Victor Jr. to the RPM Air Gap, I noticed my idle was very rough. Put a vacumn gauge on it and was not holding a vacumn. I looked at the intake bolts and saw I could turn the washers which ment the bolts were bottoming out before they tightened. I Took them out one at a time, measured the depth of holes and added another washer (2 total) which is about 1/16" and it worked.
Bob