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

[draw]

Originally Posted by 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

I think that it may have been threaded by a previous mechanic to aid in pulling it out of the housing. It doesn't affect the function of the oiler tube at all...

[draw]

(But) installing and removing the oiler tubes several times was more than they could bear. Ended up buying two new ones from our host...



Red Loctite for the plugs...



Lock them in with some Loctite epoxy using a craft syringe for an applicator...



Just a dab will do ya...



Almost looks like the factory did it...



And the last step is to red Loctite in the plugs...



All done! Once I figured out the angle that I needed to drill and figured out my "sine plate," it wasn't too bad of a project...

[fallingat120mph]

Good stuff and great photos. Nicely done.


Erik

['78 SC]

+1 very nicely done.

The threaded plugs I installed in my recent build leaked and required a partial teardown to access. I then used Loctite 592 to seal the plugs. I selected it based on specs and a preference to have something that would prevent leaks and could be easily removed. Loctite has hundreds (thousands?) of sealants, that's the one I used. It appears you're using the red thread locker.

Loctite 592

[Henry Schmidt]

Keep in mind that Supertec has new tooling that allows us to convert 47mm cam housings to 49mm.
Our deflection testing shows us that three journal cam housings are mote than adequate for any street application.