Home › Forum › Ask A Member › 1976/77 OMC 9.9 & 15 carb needle valve bearing › Re: 1976/77 OMC 9.9 & 15 carb needle valve bearing
Many needle adjusters have a spring to hold the screw adjusters position. Since the threads are tapered and the spring pulls the adjuster against the threads the needle adjuster will normally stay in the center of the jet opening. Like in the needle tip being concentric with the passage.
Without a spring loaded needle adjuster and the needed running clearance at the threads the needle tip can orbit or become non-concentric in the jet or passage opening while adjusting or just in normal operation from vibration. That "bearing" as its called keeps the needle tip in the center of the jet opening.
When I received my motor in a box there were two needle bearings in there. One was sideways with a hole pierced through it…