A few weeks ago I installed a low base circle-high rise cam (09 cam) which gives me 7.5 mm valve lift instead of 6 mm and longer duration openings. I have much more power (torque) across the most used RPM range, like from 1800 to 4000 RPM. But I am not quite satisfied with the smoothness at idle: I have adjusted the idle speed and mixture and verified that the fuel supply to cold the start valve shuts off as it should and that the warm-up device shuts off as well. The idle speed in neutral is about 750 and in gear, when the "magnet" is extended it is about 700 rpm. And there is a slight humping present at both these idle conditions. It does not go away when I change the mixture. I bothers me a little. Normal people would not detect it. Plugs look fine, compression is pretty even. I have not checked the spray pattern of the nozzles. At speed the engine runs strong - no humping. The humping at idle is like a dog who limps just a little. but when he runs, he does not limp at all. And yesterday I found that there is a surging present when the engine is about halfway warmed up: the rpm at idle fluctuates a little. It is not steady but goes up and down maybe 50 rpm. That condition disappears completely when I drive on. Any ideas?
