Crankcase Breather vent pressure
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Road Warrior
Joined: May 2013
Posts: 1,430
Likes: 55
From: Florida
Crankcase Breather vent pressure
Ok, I'm fabricating a breather vent to a catch can, My prototype works well. So I'm going to drill and tap my chrome SE breather backplate and use two hoses, Eliminating the tee. While out rounding up parts I found a small threaded filter, the kind that looks like a clump of copper grains packed together, Which got me wondering how much pressure does the vent put out, and would this filter be too restrictive? The catchcan is located/hidden in the cowbell with a petcock on the bottom and so far I've left the hole on top empty, no pressure on the vent at all. Any thoughts or input? Photos soon.
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Road Warrior
Joined: May 2013
Posts: 1,430
Likes: 55
From: Florida
Update, the good, the bad and the ugly, Changes from prototype, First I found another filter that's a lot less restrictive but taller and cone shaped. So I moved the can down about half an inch. Moved the petcock to the outside so it wouldn't show under cowbell, put a plug in the bottom hole. Drilled and tapped 2 90deg fittings in catchcan and breather backplate. Just eyeballing I could tell the front hose was gonna be close to head fins, but too late to turn back now. Was right, close fit but finally got both hoses through after fn with it for a few hours, over,under,around and back. OK good enough to test and see if I melt the front hose. I really wanted to go for a ride today. So as I'm tightening the bolts into the throttle body, oops,shiat, dammit, that didnt feel good. Stripped the threads out of the TB! That's it I'm done for today. After calming down and having dinner, I remembered I have some extra brass inserts for fairing screws and they are 1/4 x 20 threads also. So tomorrow I'll drill and tap one of them in and should be good to go.
Here' a couple pics of the project.
Here' a couple pics of the project.
Last edited by Smokey Stover; Dec 3, 2014 at 08:52 AM.
Outstanding HDF Member
Joined: May 2008
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From: Ashland Ohio
Going uphill with a vent line makes a plumbing p trap. Not good, IMHO. The line should always run downwards for its whole length.
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Road Warrior
Joined: May 2013
Posts: 1,430
Likes: 55
From: Florida
I know that's why I was trying to find out how much pressure it puts out at idle and at higher rpm's .
I figured if it pumps oil up to the top of cylinder head then a small hump might be ok. It's mostly vapor until it condenses right? Anyway I should have been more clear, The hoses are level with breather bolts now, then down to to can after they're past the intake manifold. I was trying different routes to keep the front hose away from the head heat. Was difficult because I didn't pull the gas tank this time,It's nearly full. If the head melts the hose I'll have to go back to the tee into one hose, I went to dual hoses because
I thought a tee being so close to the source that the pulses would be competing with each other for the exit, Or blowing mist back and forth, If that makes sense. I'll try to snap a photo later when it's all apart again. Hard to see anything under tank between the heads, it's all black lol.
I figured if it pumps oil up to the top of cylinder head then a small hump might be ok. It's mostly vapor until it condenses right? Anyway I should have been more clear, The hoses are level with breather bolts now, then down to to can after they're past the intake manifold. I was trying different routes to keep the front hose away from the head heat. Was difficult because I didn't pull the gas tank this time,It's nearly full. If the head melts the hose I'll have to go back to the tee into one hose, I went to dual hoses because
I thought a tee being so close to the source that the pulses would be competing with each other for the exit, Or blowing mist back and forth, If that makes sense. I'll try to snap a photo later when it's all apart again. Hard to see anything under tank between the heads, it's all black lol.
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Road Warrior
Joined: May 2013
Posts: 1,430
Likes: 55
From: Florida
Thanks for the reply Wurk_ Truk, I appreciate and respect your opinions, You help lots of members.
So, Backplate is off again, takin a smoke break before drilling. Snapped a couple more pics,
First from right side, You can see hose running parallel to bottom of front rocker cover.
And from left side, going under temp sensor and thermostat wire to Wards FCS. This is where I was worried about heat off of the fins, It doesn't actually touch but looks like it in photo.
So, Backplate is off again, takin a smoke break before drilling. Snapped a couple more pics,
First from right side, You can see hose running parallel to bottom of front rocker cover.
And from left side, going under temp sensor and thermostat wire to Wards FCS. This is where I was worried about heat off of the fins, It doesn't actually touch but looks like it in photo.
Thread Starter
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Road Warrior
Joined: May 2013
Posts: 1,430
Likes: 55
From: Florida
The rest of the story, Had all my tools out was sitting on my stool just staring at the stripped out threads, Thinking I don't want to drill this,There's not much meat around that hole already and running a tap in might just crack it. So I just sat there until it came to me. One time too much red locktight leaked out the backside of the hole and the threads on the bolt were only 3/8" into it. So I ran a 1/4x20 tap in to chase the threads all the way through, Found a 3" stainless machine screw and started digging through my nuts an bolts trying to find a sleeve the same length or close as the spacer on the original bolt, No luck but I did have plenty of locknuts, So I put the screw through the air filter then a locknut then another with a flange upside down locked em together same length as the original spacer from inside of filter to the plate, Screwed righ in, Made my day!