I used the oil port to the rear of the oil filter above the in line galley plugs.  It came out easy.  

What was your solution?

Problem solved, thank you!!

I wanted to remove 1 of the three not used for a gauge and not tee the warning light. I finally gave up. I’m guessing the rebuilder didn’t remove them during the engine overhaul. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

I have tried the metric also.  These are Snap-on Allen hex sockets, so tool quality should not be an issue. I tried the 7 MM and it is also not tight.  Part of the problem is that the rebuilder (an expert Y-Block shop) used brass which is soft.  Maybe they do not make them in steel, but the inner hex rounded when I tried to exert enough pressure to remove the plugs.  I am thinking of getting a cheap tool and J B welding it to the plug then trying to back it out.

As Stuey has pointed out, later Allen keys are often Metric, just to make things more complicated !..                                                                                                                                                                                   ,


Paul

would a 7mm allen key be a better fit?
stuey

I am trying to remove the threaded oil galley plug that is one of the three hex head plugs on the left side of the engine to install an oil pressure gauge.  The plugs have a hex or Allen head that is loose with a 1/4" Allen and 5/16" will not go in. It stripped the 1/4" one as I was trying to unscrew it.  It appears that the engine builder used brass plugs.  I want to get this out without drilling as I am worried about getting brass filings in the oil passages and eventually damaging the new engine. Any thoughts?