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


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14 hours ago, M2M3 said:

3 is how it is done with the S14.

Sort of.   S14 has a centrifugal separator with liquid drain to the pan and has a much more significant oil separator in the valve cover than the M10 has.  Vapor is routed to the air box.  One can be easily built for the M10 with a grab of SS pot scrubber in the tube with a liquid drain to the pan.  I make one for the M10.  Most oil carryover from the vent was captured.  The pot scrubber provides surface area for the oil to coalesce onto and form drops large enough to drain instead of being carried along to where ever the tube is routed to, i.e. air cleaner).

 

1 hour ago, '76mintgrün'02 said:

  I've also read that EFI systems like that number, but carbs prefer it a bit richer... depending on the circumstances.

Those EFI systems that use narrow band O2 sensor only control to 14.7 A/F ratio because the sensor produces a 0-1 volt output with a curve that cannot be controlled outside of +/-0.5 A/F tolerance. So the EFI systems with a narrow band sensor flip the A/F ratio back and forth across 14.7 A/F ratio (GM called it switchover count)

Today wideband sensors are readily available and can be controlled at ratios between 10.0 and 20.0.  The engine may not fire at the extreme of A/F ratios but the control loop is not limiting.

Liquid fuel is not what burns, fuel vapor is what burns.  Carbs can run ok at 14.7 if it can be tuned.  They take more fuel because unvaporized fuel does not burn efficiently.  FI (EFI or HP mechanical, i.e. KF) sprays evaporate fuel faster and so better fuel economy.

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11 hours ago, '76mintgrün'02 said:

That seems like a vacuum leak to me

This is the way everything was plumbed when new.

I've thought the same thing...vacuum leak, but find no evidence with a gauge or plugging/unplugging to see any change.

The small tube on the air cleaner is connected to the large vacuum port on the intake manifold...so it is not "ported".

This also sucks through the charcoal canister, which is also vented to atmosphere. 

Soooo... the fuel tank vent sucks air in through the charcoal canister as fuel level drops, manifold sucks air in when engine is running, valve cover is spewing oil fumes into the air cleaner, and (cool) fresh air is feeding the carb through the snorkel. 

If everything is connected properly, everything should balance out (no leaks) ?? 

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3 hours ago, jimk said:

Sort of.   S14 has a centrifugal separator with liquid drain to the pan and has a much more significant oil separator in the valve cover than the M10 has.  Vapor is routed to the air box.  One can be easily built for the M10 with a grab of SS pot scrubber in the tube with a liquid drain to the pan.  I make one for the M10.  Most oil carryover from the vent was captured.  The pot scrubber provides surface area for the oil to coalesce onto and form drops large enough to drain instead of being carried along to where ever the tube is routed to, i.e. air cleaner).

yes.  that is the basic idea.  i was intentionally simplifying.  vapor goes to intake, oil goes to oilpan.

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On 6/9/2021 at 6:34 PM, 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.  

 

Haha, super newbie question here. Why is the cute little air filter a bad idea, aside from the potential for making a mess? Honestly need to know, as that's what my car has.

 

It certainly is darn cute, and dead simple, which is why I've kept it. The engine was built by PO in 2012 and doesn't seem to blow a terrible amount out of there. I guess I've had to wipe away some greasiness a time or two over the past couple years in the ~3,000 city and canyon miles that I've put on the car, but nothing that has seemed unreasonable to me. Are there other downfalls of running that?

 

Edited by toddfx
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7 minutes ago, toddfx said:

 

Haha, super newbie question here. Why is the cute little air filter a bad idea, aside from the potential for making a mess? Honestly need to know, as that's what my car has.

 

It certainly is darn cute, and dead simple, which is why I've kept it. The engine was built by PO in 2012 and doesn't seem to blow a terrible amount out of there. I guess I've had to wipe away some greasiness a time or two in the ~3,000 city and canyon miles that I've put on the car, but nothing that has seemed unreasonable to me. Are there other downfalls of running that?

 

you must not drive it hard.  at any "fun" rpm, the filter clogs with oil, then blows out making huge mess.  bought a car that was set up like that.  after one round of cleaning up oil, the filter was tossed in trash and breather bottle installed.

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6 hours ago, Leucadian said:

I'm dealing w/ some blow-by issues as well. 

I used the dashpot from the original Solex to crack the throttle open a bit during deceleration. This dramatically reduced the white smoke out of the exhaust pipe. Not sure what effect it has on the blow-by from the valve cover, but will test my catch can soon.

For those who haven't seen a dashpot on a Weber...here it is, with a sketch on how it operates.

Weber Linkage.jpg

Speed Relay.jpg

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The following shows my catch can setup with a stock, late model air cleaner. I sourced an oil/fuel compatible hose that had pre-formed 90 degree ends, cut the hose in half and mounted the catch can to a repurposed bracket of some sort I found in the basement of the house my wife and I bought a few years ago. This setup works well.

 

Doug

 

cc_far.jpg

cc_close.jpg

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1 hour ago, doog said:

The following shows my catch can setup with a stock, late model air cleaner. I sourced an oil/fuel compatible hose that had pre-formed 90 degree ends, cut the hose in half and mounted the catch can to a repurposed bracket of some sort I found in the basement of the house my wife and I bought a few years ago. This setup works well.

 

Doug

 

cc_far.jpg

cc_close.jpg

That looks like just the right setup for me. How often do you have to empty the catch can? Do you notice it fills more during “spirited driving “? Does the vapor mess up the inside of your air cleaner? Did you get the hoses off the shelf at an auto parts store?

 

I’m thinking I might also follow Toby‘s advice and shove some stainless steel kitchen scrubber in the first hose to catch/condense the oil so that it can drip back into the valve cover

 

Thx!

Jeff

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I check, and empty if necessary, the catch can every 1,500 miles or so. While it always contains something, it's never, literally, full.

 

With the catch can in place, there's a lot less crap on the underside of the air cleaner.

 

I bought the hoses from either Jegs or Summit Racing: can't remember which.

Edited by doog
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