Camshaft Housing/Tower Modification - Drilling the 4th Journal

[draw]

I searched the forums thoroughly but didn’t find much information on drilling out the 4th journal in a 2.7 camshaft housing to provide oiling to the cam. It’s not exactly rocket science, but I thought I’d contribute to the knowledge base by sharing how I plan to modify mine—for anyone who might be searching for this down the road.

Also, I need to give a shoutout to Henry for pointing out during my engine build that I was using 4-journal cams in a housing that hadn’t been modified to supply oil to that 4th journal.

My approach to this modification might not be ideal. I’m not a professional engine builder—or a machinist—and I’m definitely not trying to be one. I’m just a doofus in a garage figuring things out.

Anyway, here goes...

First, I wanted to remove the oil tubes. Fortunately, Ollies inserted tapped plugs when they worked on the housings, which aided removal...



Marked the tube so I can remember the correct orientation...



I used two 4mm drill bits inserted into the existing oil holes on each end and a straight edge to transfer the edge of the holes to the undrilled location. You'll notice that this method hit the edge of the existing plugged oil hole perfectly, which added confidence that the alignment was good. I scribed a line, measured down 2mm (half the diameter of the 4mm hole), and marked the spot for center punching...



I mocked up the housing on my drill press. I'm using a straight edge and a 1-2-3 block to confirm the angle of the dangle is correct. When I clamp the housing down for real, I will confirm in two directions that the drill bit is perpendicular to the housing...



Here's my (planned) procedure:

1. Drill through the journal with a 4mm bit.
2. Insert the oil tube, align it and drill that with the 4mm drill bit.
3. Drill into the housing with a 4.2mm bit to a depth of 10mm.
4. Tap the hole using a M5x0.8 coarse tap
5. Insert M5 x 6mm allen set screw with blue Loctite.

Let me know if I'm missing anything. Fingers crossed...

[draw]

This probably won't come as a surprise, but tilting the table and clamping the housing wasn't workable.

Instead, I made up a sine plate for $10 in plywood and a $6 piano hinge. The valve cover surface is at a 30 degree angle. I added a couple of stops to hold that angle...



I screwed the housing to the plate and aligned the drill...



Bolted the plate to the drill press table...



I inserted the oiling tube back in the housing and used the pointed plugs to properly locate it within the housing. Drilled the mark all the way through the oiling tube and the journal with the 4mm drill...



After drilling a 4.2mm hole to a depth of 10mm, I tapped the hole with the M5x0.8 tap...



Test fit the set screw...



And Bob's your uncle!

I deburred the journal with a red Scotch Brite pad. Now to do the other side...

[11BC2]

Nice!

[Magyar Kiwi]

Hi
Good work.
However, looking at your second photo, it looks like the threaded plug seated on and damaged the end of the oil/spray tube ?
Cheers