David Biele Dave when I built the 452 motor had the same problem with
oil leaks. Found out the running a PCV in the r/s valve cover helped alot.
Couple things to check, make sure that the gear is not sitting on the block inside. You want a little play if you lift and lower the shaft. If the shaft is being pushed up, you need to redrill and move the gear to get the correct play. The directions for the MSD explain how to check and move the gear if needed. This depends on how much machine work was done on the mating surfaces, Intake and heads. The other thing you can do is get 2 gm distirbutor gaskets and glue them togeather and let dry. Mark the rotor position and housing position and remove. Install the gaskets on the lower housing and put back in motor. Tighen until you can't spin the distributor easy and stop. This should seal your leak without and problem. The other thing to check is, the front of the intake to heads area. Is it possible the
oil leak is coming from the corner? Buying the
oil leak kit with dye and glasses makes finding and fixing the leaks alot easier. I don't recommend RTV on this location because of adjustment. Once the seal is broken from adjusting the distributor it could leak real easy. Rick L.