I'm quite sure this has been discussed on here somewhere at some point, but I'm not able to find it so I figured I'd share.

I wanted -10AN fitting on my valve cover and didn't want to deal with welding in AN bungs. After a few measurements, I found an easy button. Just tap the two existing holes for NPT fittings.

The PCV valve port on the passenger side will be tapped for a 1/2 NPT fitting. The vent port on the drivers side will be tapped for a 3/8 NPT fitting.

Remove the valve cover and then flip it over and remove the covers on each side the cover the ports.
1. Drill the passenger side out with a 3/4in drill bit and tap with a 1/2 NPT tap.
2. Remove the 90deg elbow on the driver's side (clamp vice grips on it and tap the vice grips with a hammer to remove), drill the hole out with a 9/16 drill bit and tap with a 3/8 NPT tap.
3. Install your desired NPT to AN adapters and plumb your catch can as you see fit.

Tools: (Harbor Freight FTW)
Drill Bit Set Item #61802 $29.99
NPT Tap Set Item #91395 $13.99

Total Price: $43.98 ($35.18 with 20% off coupon)

 

3/8 NPT to AN10 is a small hole. One of the reasons for running a bigger bung is to have a bigger hole.

Cool anyways tho.

 

Isn't 3/8" the same diameter as -6AN? If 3/8 to -10, this would create a bottle neck, no?
Looks good though. That engine looks very clean, props for that. Mine looks like somebody started their diesel truck on it.

 

3/8 NPT has roughly a 1/2in ID, the -10AN has a 5/8in ID, so yes I am giving up 1/8in of hole size. You may be able to drill and tap for 1/2 NPT on both side, but it would leave the wall thickness on the driver's side pretty damn thin.

 

I love your upper radiator hose configuration

 

I have done that and thin is not the word for it... If you don't drill that exactly centered, When you tap it you will see what I mean. I wouldn't cry about an eighth of an inch if it taps as nicely as you've done it.

 

Did you drill out the passages between baffles on the hot side? Flow is big time restricted there.

 

Yeppers!

 

Thanks! I'm pretty happy with the way it turned out.

 

Nice!!!

 

Once the fitting is screwed in, it can also be enlarged with a drill bit "a reasonable amount",

 

I had a 1/2" bung welded in and the little hotside hole welded shut. I tapped the PCV hole for 1/2"NPT fitting similarly to you. I also opened up the internal passages. Larger holes and hoses have generated much less oil in the catch can probably due to slowing the speed of the air and allowing the the oil to settle out rather than being carried by the velocity.