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You guys are killing me! re: catch can for valve cover breat


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I’ve been pouring over all the threads on this and I think it would be great if some of you wise gentlepersons would drive a stake through it’s greasy heart. I have a de-smogged “75 (in Sahara!)

 

The following are my assumptions, please feel free to set me straight: 

-Original design was to let valve cover breath, and burn any gasses (not oil) by dumping them back into the carb (just a hose from valve cover to the air cleaner)

-Original design didn’t take into account a worn motor with blowby pushing oil into the hose (almost all our motors are worn now, right?). Culprit is worn rings?

-I’ve made a lot more assumptions I can’t think of right now

 

If stock is a hose straight to the carb what did the original engineers intend? And if that doesn’t work now what do we do?

I think it would be best to keep the oil inside the motor (modify inside of valve cover)? Not practical

2nd best: let oil drool back into the valve cover by making the hose long with a continuous slope back to the valve cover Not practical

3rd: catch can/breather with a drain to the oil pan/crankcase Not doin that

4th: catch can/breather with a hose to the carb My current plan

5th: catch can/breather with hose to the street below nope

6th: hose from valve cover straight to the carb (like stock?) and clean out your air cleaner as needed?

Else, let it blow & keep yer fingers xed?

 

All that’s for the liquid oil, but…

The vapor/atomized oil/unburned hydrocarbons (what’s in there anyway)?

Seems like the original engineers thought it was a good idea to make it a more or less closed system and run the vapor through the motor again

 

Diagrams & sketch (great sketch drawn by a member, can’t remember his name) of smog systems seem to not include the hose. The outlet on the valve cover is just open to the atmosphere??!!! So not important from an emissions standpoint? (back to: what’s in that vapor anyway?)

 

Also, what kind of driving are we doing? I assume most of us take the car on “spirited drives” so the system would need to be able to handle that. But what about on the track? Toby says his car pukes oil out of that hole but I imagine he has a highly modified motor and very sticky tires. If he’s pulling 1 lateral g in a right hand sweeper at speed, from the motors point of view it’s like he tipped the car up on 2 wheels and hit the throttle. I can see some oil finding its way out that hole. Maybe 1 system for the track and 1 for normal hooning? 

 

Thanks!

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4 hours ago, Oakland Jeff said:

Seems like the original engineers thought it was a good idea to make it a more or less closed system and run the vapor through the motor again

It was against the law to dump it to the road or environment.  What it had originally was state of the art in foreign stuff.  Domestic stuff had a PCV valve in the hose and it went to the intake, not over the carb inlet.

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33 minutes ago, M2M3 said:

3 is how it is done with the S14.

4 is the common right way do it.

 

don't overthink this.  the solution is simple.  

 

PS - you forgot the most common wrong answer.  put a cute little air filter right on the valve cover.  

Ha! I ruled out the cute little filter along time ago 🙂

 

 

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I've been mildly annoyed at the oil that accumulates inside the stock air cleaner.

I took a stainless steel coffee mug, drilled two holes in the screw top, and fastened a tube from one hole to the bottom of the mug and a small K&N oil filter to the INSIDE top of the other hole.

Valve cover vent will go to the bottom of the mug, and exit thru the filter to the stock air cleaner.

Haven't installed it yet, but will report results shortly. 

BTW, I also use the small vacuum hose attached to the manifold vacuum to help "suck" things along. (see lower part of sketch).

John

 

Fuel System.jpg

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1 hour ago, John76 said:

BTW, I also use the small vacuum hose attached to the manifold vacuum to help "suck" things along

 

That seems like a vacuum leak to me, but I think we've discussed this before.

 

I use the stock air cleaner setup and don't mind wiping a little oil off the lid when I open it.  It's a little gross in the winter though, when sour cream gets spewed up there too.

 

Today I waxed the underside of the lid, after wiping the oil off

 

IMG_9103.JPG

 

and then did the same to the dome.  Now the air just slides right into the carb.  Super ssslippery sssssmoooth.

 

IMG_9101.JPG

 

If you look inside the breather tube, you can see that they necked it down inside.  I think this is to help spray the oil over the carb.  It is also set up so that oil drips can run back into the valve cover.

 

I waxed the top side too, just for fun.  It's one of the only shiny parts of my car.

 

IMG_9120.JPG

No catch can on mine.

 

Tom

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7 hours ago, John76 said:

I've been mildly annoyed at the oil that accumulates inside the stock air cleaner.

I took a stainless steel coffee mug, drilled two holes in the screw top, and fastened a tube from one hole to the bottom of the mug and a small K&N oil filter to the INSIDE top of the other hole.

Valve cover vent will go to the bottom of the mug, and exit thru the filter to the stock air cleaner.

Haven't installed it yet, but will report results shortly. 

BTW, I also use the small vacuum hose attached to the manifold vacuum to help "suck" things along. (see lower part of sketch).

John

 

Fuel System.jpg

Hi John, yet another solution! Why does this happen? It couldn’t be a design flaw… no one would even suggest such a thing. 
 

BTW I referenced a great sketch of the smog system, that was yours, thx!

Jeff

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6 hours ago, '76mintgrün'02 said:

 

That seems like a vacuum leak to me, but I think we've discussed this before.

 

I use the stock air cleaner setup and don't mind wiping a little oil off the lid when I open it.  It's a little gross in the winter though, when sour cream gets spewed up there too.

 

Today I waxed the underside of the lid, after wiping the oil off

 

IMG_9103.JPG

 

and then did the same to the dome.  Now the air just slides right into the carb.  Super ssslippery sssssmoooth.

 

IMG_9101.JPG

 

If you look inside the breather tube, you can see that they necked it down inside.  I think this is to help spray the oil over the carb.  It is also set up so that oil drips can run back into the valve cover.

 

I waxed the top side too, just for fun.  It's one of the only shiny parts of my car.

 

IMG_9120.JPG

No catch can on mine.

 

Tom

That is a fine looking air cleaner! Didn’t you used to have a little snorkel in there that you made from a curved piece of hose you found it at wrecking yard? I may start with the straight hose/ no catch can method (utilizing the KISS principle) to see how it goes. I probably won’t be waxing the inside of the air cleaner though 🙂

Jeff

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Thank you.  The ribbed version was '76 only.  I did have a little rubber tip there, but took it off.  It kept oil off of the lid, iirc, but I don't miss it.

 

030.JPG032.JPG

 

 

That little snorkel was inspired by another idea I tried, back when I had the little Weber rectangular filter; where I did a little plumbing with copper pipe.

 

015.JPGI also plumbed the gas tank vent line into the breather fitting, for a little added boost, in the new fOrced induction situation.

108.JPG014.JPG

 

 

Adding the stock air cleaner might be the best things I've done for my car.

 

Tom

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9 hours ago, TobyB said:

I honestly got #2 to work. 

 

But it goes to an eventual catch can that's vented back to the intake,

 

so I guess I did #6.  #2 + #4...

 

t

 

Hi Toby, I was hoping you’d respond because in an earlier thread you said yours puked a crazy volume of oil, filling your catch can after just a few minutes of driving. I’m assuming you were on the track then (I’m planning on taking my car on the track too). So, does your puked oil now go back into the intake?

 

Also, years ago read a remark here that I attribute to you. I bought my car from the original owner and it needed everything refreshed. In trying to decide which parts to buy for track use I came across your (I think) remark to keep the car bone stock, learn to drive a slow car fast, then upgrade parts as you find their limits. Seemed very wise to me so that’s what lm gonna do. Thanks 

Jeff

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8 minutes ago, '76mintgrün'02 said:

Thank you.  The ribbed version was '76 only.  I did have a little rubber tip there, but took it off.  It kept oil off of the lid, iirc, but I don't miss it.

 

030.JPG032.JPG

 

 

That little snorkel was inspired by another idea I tried, back when I had the little Weber rectangular filter; where I did a little plumbing with copper pipe.

 

015.JPGI also plumbed the gas tank vent line into the breather fitting, for a little added boost, in the new fOrced induction situation.

108.JPG014.JPG

 

 

Adding the stock air cleaner might be the best things I've done for my car.

 

Tom

Ha! I love the copper faucet! You don’t mess around Tom. I have the Weber 32/36 jetted according to C. D.eisle’s specs w/ rectangle filter and the car goes like a scalded cat. So l’m not inclined to go back to the stock air cleaner. Too much fabbing, prepping, painting and waxing :) Maybe someday 

Jeff

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30 minutes ago, Oakland Jeff said:

I have the Weber 32/36 jetted according to C. D.eisle’s specs w/ rectangle filter and the car goes like a scalded cat. So l’m not inclined to go back to the stock air cleaner. Too much fabbing, prepping, painting and waxing :) Maybe someday 

 

I'm not trying to twist your arm, but the cool air intake snorkel would give you even more pOwer.  1% per 10 degree temp difference, so they say.

 

I use @c.d.iesel 's prescription too, with a larger primary air corrector to lean it out a little bit.  I used one I had on hand and it was three sizes larger, at 160.  (edit -- he suggests using 140)  It seems to cruise in the upper 13s on the AFR gauge most of the time, but will creep up over 14 on an incline when running on just the primary side.  It doesn't seem like enough of a problem to chase it (right now), but it is tempting to order a 155 air corrector and see what that does.

 

Tom

Edited by '76mintgrün'02
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17 minutes ago, '76mintgrün'02 said:

 

I'm not trying to twist your arm, but the cool air intake snorkel would give you even more pOwer.  1% per 10 degree temp difference, so they say.

 

I use @c.d.iesel 's prescription too, with a larger primary air corrector to lean it out a little bit.  I used one I had on hand and it was three sizes larger, at 160.  (edit -- he suggests using 140)  It seems to cruise in the upper 13s on the AFR gauge most of the time, but will creep up over 14 on an incline when running on just the primary side.  It doesn't seem like enough of a problem to chase it (right now), but it is tempting to order a 155 air corrector and see what that does.

 

Tom

We’re trying for 14.7 on the gauge, right? I am concerned about running too rich and dumping unburned fuel out the tailpipe. I have a 145 primary air corrector, no gauge though

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Just now, Oakland Jeff said:

We’re trying for 14.7 on the gauge, right?

 

Not really.  That is supposed to be the magic number, but it varies depending on the fuel.  Winter blends are a bit lower, so I've read.  I've also read that EFI systems like that number, but carbs prefer it a bit richer... depending on the circumstances.  My car idles best down around 12.5, for example and once it gets up around 13 it starts hunting a bit.  Supposedly you get the most power down around 12-12.5 and that's what I see when I mash the pedal, bringing in the secondary side.  Higher is better for fuel economy, of course.  Keep in mind, my experience/knowledge are quite limited.

 

Tom

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