I’m leaning towards a bad valve spring on cylinder 8.
But what I don’t understand is why I’m not seeing something obvious with the vacuum gauge hooked up.
But it makes sense, only cylinder 8’s plug isn’t firing correctly all the others look pretty good.
It idles fine and drives perfectly fine below 2500 rpm.
Once you get up to 2500 or higher it just gets rough.
I’m seriously thinking valve spring on cylinder 8 but the only thing that has me wondering if that’s really the case is the vacuum reading at idle appears fine.
Maybe I should hook up the vacuum gauge and sling it up to 2500 rpm and watch it and see what it does then.
Cause from what I’ve read online about bad valve springs and the symptoms I’m having it sure makes sense at this point.
Specially with cylinder 8 pumping out good compression.