Quote:

---

Vacume leak on the intake, possible miss adjusted valves, or both!
The intake needs o be checked put it on dry checkit with feeler gage top bottom side to side, do not use cork end gaskets if it is aluminum just use gasket sealer . nice 1/4 bead will work great.
If intake checks out, use small amount o sealer around the intake ports top bottom of gasket .
Most small blocks love to leak on the valley side

---

A sure test to see if you have a manifold to head port vacuum leak on the crankcase side is to block off all the openings on the valve covers ( breather, PCV, Oil fill cap, Etc. ) and see if the idle improves with everything blocked off. If it does, you have a vacuum leak to the crankcass.