I was using my new vacuum gauge tester on carb and new advance timing light that indicates the RPM.
I have a 1991 454CID.
Is there any value to readings less then 700 RPM? Issue number 1 was that I can see very clearly that I was trying to idle at 600 RPM (out of gear). The vacuum was showing jerky movment that goes away as the idle increases. That looks like worn value guides from what I understand. At the 750 RPM the vacuum is at 17 and much more stable. However I see (and now with the clues hear) changes of 70 RPM up and down. I cannot get a soild idle. I think I need to tune carb more? Is there any value to sub 600 RPM out of gear? I having idle and sub 17 vacuum issues.
I remember my manual said 600 RPM in gear and 600 to 750 is the idle