Black Plugs in Adjacent Cylinders and Vacuum Jitters
When taking a vacuum profile for the selection of a PCV (car did not come with a PCV) to reduce crankcase pressure and crank slinger oil seepage, I was surprised to find a vibrating vacuum reading between 7 and 15 inches Hg at idle (900RPM). Since the engine preformed without an indication of any problems, I was not expecting to see this condition.
Upon suggestion that the condition could be the result of tight valves, and since I had re-bushed and adjusted the rockers 3 months earlier, this seemed to have a high possibility. When extracting the plugs in preparation for the adjustment, I found perfect color on all plugs but cylinders, 2 and 3, which were black. Since this is a straight 6, 2 and 3 are adjacent cylinders. While Iím waiting for a friend to return my compression gauge, I would appreciate any suggestions.
All the best,