Rb head oil drain dimensions

[Chids34]

Rb head oil drain dimensions

Hi all,

I've been looking at buying a rear head oil drain kit for my 25/30 such as the one spool or Franklin engineering make.

However I work in a machine shop and could easily make such a drain myself, I was wondering however if anyone had one lying around they could take some measurements off (preferably vernier)

Mainly chasing total width, length of drain spigot, diameter of drain spigot, the dimensions of the oil ring groove, pcd of bolt holes. If anyone has the dimensions I'd be happy to make extras at a fraction of the cost! Thanks

[KiwiRS4T]

Don't bother, waste of time they don't do anything.

[rcs_888]

I have a spare head at a mates place i will try get some measurements tomorrow arvo

[Chids34]

I would disagree that they don't do anything, many people have this oiling problems this is a pretty simple fix. At worst it avoids a potential problem.

[KiwiRS4T]

8 hours ago, Chids34 said:

I would disagree that they don't do anything, many people have this oiling problems this is a pretty simple fix. At worst it avoids a potential problem.

If you are serious about preventing an oiling problem read (at least the last third) of this thread and you will realise that the rear head drain hasn't helped anyone:

 

[iruvyouskyrine]

They sort of work, but not in the way you think they do. Read the oil control thread to get a more complete understanding of RB oil control.

[KiwiRS4T]

7 hours ago, iruvyouskyrine said:

They sort of work, but not in the way you think they do. Read the oil control thread to get a more complete understanding of RB oil control.

I haven't seen any evidence that they have done anything good. In fact having seen what comes into the catch can from the sump breathers I can't see that piping that up to the back of the cam covers is a good thing.

[Papichulo96]

Bump on this to not make another post,

had a ‘head drain’ leak on me and have the engine out as we speak. Planning on just putting a new freeze plug back in , plug the tapped holes and just be done with that headache. 
 

Now I still want to relieve pressure to allow oil to pass down the blocks returns easier.
I’ve seen catch cans with multiple vents help folks with this issue on this forum. 
I’m wanting to make my own.

I have some pictures here of my setup if anyone can help how I should plumb and design the catch can I would deeply appreciate it !

 

rb25

Oil upgrades:

1.0mm restrictor

n1 pump/billet gears

extended crank collar 

extended sump with trap doors/w welded fitting

 

 

[Dose Pipe Sutututu]

Yeah the head "drain" is rather a sump/crank case vent.

My catch can stopped filling up after venting the sump to the catch can.

I have 4x fittings in mine, which is about 5Ls.

2x cam, 1x sump vent/catch can drain, 1x fitting back to the intake and a massive breather which can be blocked so it's a fully sealed system.

[Dose Pipe Sutututu]

21 hours ago, Papichulo96 said:

have some pictures here of my setup if anyone can help how I should plumb and design the catch can I would deeply appreciate it !

I personally would run 2x from the cam covers into the catch can, 1x sump vent to catch can (would mount this at a low point of the catch can, so it can also act as a drain). I would see if you can run a -12AN down there to improve venting and also draining. The head drain thing, just drain that back to the sump on the other side.

Catch can to be vented, unless you plumb or back to the intake.

[Papichulo96]

On 2/26/2025 at 3:22 PM, Dose Pipe Sutututu said:

I personally would run 2x from the cam covers into the catch can, 1x sump vent to catch can (would mount this at a low point of the catch can, so it can also act as a drain). I would see if you can run a -12AN down there to improve venting and also draining. The head drain thing, just drain that back to the sump on the other side.

Catch can to be vented, unless you plumb or back to the intake.

Awesome thanks for the reply Man! I already plugged up the back just cause I can’t take a chance on it leaking on me again haha. But i will fab a catch can with 2x for the cam covers and a lower one for the sump vent. 
 

Now as this will drain back as well , Is there any concern I should have of the oil being drained back. I don’t run e85 or anything .

 

2nd question is, from the picture does it seem that my sump fitting is above oil level? Silly question but I rather have someone’s experienced opinion lol 

[Dose Pipe Sutututu]

No concern, especially not on E85 you won't really have an issue with moisture. You could put a ball valve on it and only open it when you're going to punish the car.

On daily commutes you wouldn't need it open to vent the crank case.

I would say it's above the oil, considering that looks like it would sit above the windage tray