I think you're saying that the tacho reads 7,000 rpm when the ignition is switched on, yes? That suggests you have the cables too tight or that the valve itself isn't moving freely.
Remove the cables and pulley from the valve spindle. Now, you should be able to rotate the valve easily by turning the spindle between finger and thumb. If it won't flip-flop from open to closed this way, if there's any resistance at all, then the valve is binding. It's not unusual for the spindles to get bent slightly and this will cause binding. You can check the alignment with a straight edge. With care, you can bend the valve back straight again. Hard to describe how to do it but you'll figure it out, I'm sure.
If the valve does move freely, the cable adjustment is probably the culprit. You need 1.5 - 2mm of freeplay.
I assume you've been using Pat's Site as the bible for your work so far?