Before heading out for a compression tester adapter to fit the spark plug seat: Donna's 390 motor runs again, but it gets stuttering and extremely choppy outside of Idle, especially once in Drive, stalls out or threatens to. Cylinder #7's header pipe isn't heating nearly enough, the plugs check out fine. Same results when switching out plug wires. with the valve cover off, all rocker arms are doing their thing, hard to tell visually (am about to take the pair of p'rods out to see if they're bent. How can I tell if the lifters are bad without having to take off the intake to check on them? WTF? At least all the wiring work as paid off, she starts right up, keeps in idle, is just stuttering and coughing. Well, gonna get that adapter after lunch, thought I'd have you all chew on this one. Anyone experience this? Any ideas?
Sounds like maybe you have the plug wires in slightly the wrong order. If all 16 rocker arms are moving, you should be okay, unless one (or more) of them has excessive preload and isn't allowing the valve to shut completely. Could be a lot of things. I would start with the compression test on each cylinder, make sure that mechanically it is operating normally. Then check firing order. Report back.
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