Larry,
Your elbow is more educated than mine.
Jim,
I've had 100% success with a mill jig that indexes off all 5 of the top mounting screw holes and taking a cut with a 1" end mill. AFAICT, that's what the factory did to drill the hole to begin with; there are no jig-alignment pads on the part.
Steve,
Personal taste, but I wouldn't introduce any more seams than I had to in any hydraulic pressure joints.

_________________

Ron,
My point was that lacking the sophistication of a vertical end mill or a quality drill press to do what you or Jim Fleming described it can be done with simple tools and a little care, Given a simple choice I would choose the machining method too !
My elbow, ? well as the years have gone by they do require more Nivea to keep the skin from drying out. So It must be the Nivea cream !

_________________

I've repaired a few Zenith carb top covers and using a special bronze threaded insert to repair the bolt threads, my tooling will reface the gasket surface square to the threaded hole.
Due to the tightening of the bolt over the years which stretches the internal threads, I found that the bolt will tend to 'bottom out' and it won't prevent the banjo w/its gaskets from leaking.
Therefore, the original threads (if not repairng the hole w/an insert or helicoil) will need a re-tap so the banjo bolt will give a distance of 11,5-12,0mm gap between its underside and gasket face of the top cover.

Dick

Note that the aluminum & copper crush washers actually work harden after a few tightenings. You need to replace them with fresh ones so that they will crush upon tightening and seal the fittings. After several tightenings the old ones will no longer conform to the fittings and seal gas. McMaster Carr lists all kinds of metric crush washers very reasonably priced.

_________________

There are also aluminum washers with "rubber"(not) o-rings bonded to the ID. They may fix the leak. I have fixed some pesky leaks with them.

_________________

Cliff Murray

 

'55 Cabriolet Racer

'57 Speedster

'59 Sunroof

'63 Coupe Pushrod GS 2133

'67 911 S