Since forever, I've had one of these little filters acting as a cam cover breather. Every now and then I have to give that section of the cam cover a bit of a wipe to get rid of the oil mist, but it works ok. But I'm entered into a supersprint in a few weeks, and given that's a sanctioned event, the scrutineers might insist on a catch can.
On the stock Hako, there's a tube going to the stock airbox, but the K&N filters I have on the Webers don't have any facility for a breather hose. And a recent very kind gift from a good mate got me thinking. It's an old Greddy breather can, and if it looks different to the cylindrical sheetmetal ones, it's because about 10yrs ago, Greddy used to make them out of billet, so it's a pretty nice little bit of gear.
But the problem is, the outlet on the cam cover is huge, and the resulting hose I'd need to plumb in the catch can looked pretty unsightly.
Then one day I was browsing the hybridz.org forum, and noticed that a fellow aussie forum member there, RB30X offered some nifty cam cover attachments for sale. The cam cover has a strange thread, but RB30X found an industrial fitting that had the same thread, and then welded on a standard AN fitting. So you could then attach a bit of braided hose, with a pretty red/blue -8AN motorsport fitting. But recently making up new hardlines for the clutch master cylinder was fun, so that got me into thinking about maybe making up a solution with hardline...
So I get some 1/2in copper tubing from the hardware store, plus a 1/2in spring mandrel to bend it with. The little handheld tubing bender we used for the clutch lines isn't big enough to handle 1/2in tube. What you do, is you insert the spring into the tube, then bend it by hand, and the spring prevents the tube from kinking.
First things first, I have to remove the stock breather tube, which is held in place very tightly with some sealer, which has gone hard over the years.
But eventually it's out...it may look bigger than the new fitting, but the stock tube has an inner diameter of 12mm, and the new one is 11, so that's pretty close I think.
At first I thought it would look nice like this. The copper line would run along the top of the cam cover, and it would be parallel to the copper hardline I already have for the brake booster line.
This is now the AN fitting works. AN stands for Army/Navy, and is a mil-spec standard that was developed in WW2, but since then has been adopted as pretty much the gold standard for motorsport applications. It's what is inside those pretty blue and red fittings you see on race cars. First you flare the end of the tube, but unlike the brake tube, where we had to do this complicated double flare, this is just a single flare, like a trumpet in profile.
The flared tube then butts up against the male AN fitting, and when you tighten it up, that sleeve you see will compress the tube end against the AN male, and you get a nice super-tight seal. I should point out that the brake flaring tool I used flares the tube at a 45 degree angle, whereas AN really requires a 37 degree angle. So if say we were making a high pressure fuel connection, it would probably leak. But since this is just to carry low-pressure air, I reckon we're ok.
But then I realised that the end of the tube closest to the firewall is unsupported, there isn't anywhere on the cam cover where I can attach a bracket to hold the tube still while the engine vibrates. I think what will happen is that the tube will wobble about and stress the joint at the fitting. So that ain't gonna work.
The alternative was a fair bit more complex....what I quickly discovered was that making one bend in the middle of a tube is pretty easy. Just insert the mandrel, then use something like a socket, mounted in a vice to make your radius.
But if you want to make a more complex shape, then it's almost impossible to bend the stiff tube by hand, and you have to get creative.
Just the same, it was impossible to get the bends tight enough, so I needed to make a little bracket
So the tube can sit alongside the brake booster tube. The plan was for it to sit above the booster tube, but I just couldn't get the bends tight enough to sit closer to the cam cover. If I used a smaller socket to get a tighter radius bend, it would get a nasty kink in it (notwithstanding the mandrel spring inside) so this was about the best I could do.
Then we assemble the Greddy catch can, which has a nifty little tube so that you can see the oil level. The fittings are industrial brass compression fittings that I got from Pirtek, which as you will see work a little differently to the AN fitting.
This kind of fitting doesn't require the tube to be flared, you just insert the tube into the fitting, and when you tighten it, that "olive" that you see in the middle will compress into the tapered ends of the fitting, which will then crush down onto the tube and form a nice seal. It isn't quite as strong as the AN-style of fitting, but will do for our purposes.
Then we drill a hole into one of the filter covers. I'll insert a 90 degree fitting, which will be held in place by that brass nut you see there...
...and if you're thinking that we really, really don't want that nut to come undone and fly into the engine, then we're on the same page
So I drill a 2mm hole into the nut and fitting, and then insert a splitpin. Hopefully this means it stays together forevermore.
This is what it'll look like, the fitting only protrudes inside the filter a little bit
And I attach some flexible oil-safe hose.
Do up the brass compression fittings...
And we're done!
Very possibly the stupidest, most overcomplicated breather can arrangement ever
But it looks appropriately vintage I suppose. Bending the tubes was a reall pain in the arse (you should see the mountain of dead tubes under the bench) so I'm not sure if I'd ever do it like this again