I went back to it today.Drilled all the way through and added the four screws in the corners.I dont think the SOB will leak now.I have 8 screws total although I think six would do as the way John suggests.For anyone else looking to do this-very easy.Just use a good quality drill bit to correspond to the tap size.The cast iron actually drills very easily and using the small size tap makes threading it simple.

  

Mark,



I used John's method (from his Y-Block Mag. article) AND used black RTV (no gasket). No leak in 50K miles. But, since I have a straight NOS valley cover for the new motor, I MAY eliminate the screws and use only red RTV this time (silicon just won't hold paint).

6 VOLTS/POS. GRD. NW INDIANA

Mark:

I drilled mine through, never gave it a thought to make them blind holes.  Either way would work.

John - "The Hoosier Hurricane"

Thanks John! I did 4.One on each side away from that web and one each end in the middle although its not a problem to add one each corner.I have NOT drilled all the way through.Can I drill all the way through or am I better not to?Thanks!

  

Mark:

I drill 6 places and tap for 8-32 screws.  One in each corner and one on each side about midway front to back.  Be careful of these two holes, there are small webs cast in the block under there, and if you hit one of those you'll have a heck of a time getting them tapped.

John - "The Hoosier Hurricane"

I am in the process of assembling my motor.I would like to avoid future leaks around the valley cover.I have seen mentioned on this site that some of you have added extra hold down hardware.Are you drilling and tapping for bolts or just drilling and using self tapping sheet metal screws?Where are you adding extra bolts?Just the 4 corners or?My cover does not appear deformed from over tightening but it started to leak not too long after I changed it to install PCV system.Would like to modify it while the motor is apart to avoid future leaks.