What you need to do is pinpoint where the problem first started. Did it start happening before the MSD? Check the rev-limit chip, it may be malfunctioning. Also check to see if the valves may be floating. My friend bought a Mustang (too bad for him) that when he would take it to high RPM it would do the same thing. We checked it out and the rocker arms where actually pushing down on the retainers and not the valve stems. This caused the valve to come up past the retainer just enough to where the locks let the valves slide down. Intern, never letting the valve fully close. Also maybe check the gapping on the spark plug. |