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Instead of catch can, why not delete PCV?


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3 hours ago, flyingfool said:

Have you checked your fuel trims after you breather valve cover mods? you might be causing issues  

 

seen this before on racecars, but the vacuum on the engine case is much lower than a stock pcv would draw, so it's not optimum in regards to the benefits of a pcv system, maybe utilize both ideas somehow

 

you could install a super tiny motorcycle turbo dedicated only to crank case vacuum,  run it off of an exhaust primary you only need enough low pressure to keep the cank case in low pressure state and blow it out the muffler

 

Fuel trims and everything are just fine, the truck is custom tuned anyway but has no problems or CELs

 

The Exhaust flow passing by the Evac Nozzles cause a Venturi and actually pull 3-5 inHg from the other side of the almost 8ft hose on the vacuum meter I tested.

 

Seriously, it, works very well.

 

If you want to get technological about it, for race applications they sell electrical or belt driven vacuum pumps for this, but is too much money for something I can achieve with the evacuation kit:

 

1-640x479.jpg

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Anyone remember the first PVC valves?  It was a check valve stuck in as I remember on the Ford drivers side valve cover top rubber grommet  and the hose was routed directly into the air cleaner housing, before the filter element.

 

    So all that stuff was filtered before getting sucked into the Carb intake.  When the bottom of the air filter housing got covered with oil or the air filter element got oily you know you had problems. I had overhauled a couple of engines from that era and never noticed  a lot of carbon on the intake valves.  

 

   Maybe the air filter housing and filter element were acting as a catch can?

 

 

Edited by wmgeorge64
Catch Can which one is better?
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22 hours ago, wmgeorge64 said:

Anyone remember the first PVC valves?  It was a check valve stuck in as I remember on the Ford drivers side valve cover top rubber grommet  and the hose was routed directly into the air cleaner housing, before the filter element.

 

    So all that stuff was filtered before getting sucked into the Carb intake.  When the bottom of the air filter housing got covered with oil or the air filter element got oily you know you had problems. I had overhauled a couple of engines from that era and never noticed  a lot of carbon on the intake valves.  

 

   Maybe the air filter housing and filter element were acting as a catch can?

 

 

The PCV valves back in the 60s were a simple one way check valve that did two things, it allowed the engine to draw air from the crankcase by way of a large vacuum port on the engine, and it also prevented backfires from reaching the crankcase.  Most mechanics back then would pull the valve from the rocker cover and shake it, listening for a rattle and secondly, they would look at the crankcase side for crap.  When PCVs first came out, pcv manufacturers would send out their sales team to show mechanics what to look for.  The big thing was not the pcv valve, it was the breather on the other cover.  That breather is what you are referencing, they ran a line to underside of air cleaner so that clean air would be drawn into the crankcase by the vacuum being applied to the other side of the crankcase.  The breather would have a negative air pressure on it only if the engine was so tight there was no leakage around the rings.  Saabs from the 80s had their crankcase under a vacuum when running, and their fuel injection system would not allow the engine to even start if the oil dip stick was not inserted.  We had a regular customer who always had a Saab for company car that loved to trick the new oil change kid with it.  He would run a big tale to the kid about how careful he had to be with everything, don't touch this part or that part,  he had this story down pat.  When the kid was nearly finished, just had to start it to check for leaks as well as check the level again afterwards, the customer would watch, and if the kid left the stick out, about half oil change kids leave the stick out for whatever reason, or if he didn't the customer would reach in pull the stick out about an inch and just make some comment about a finger print or a spot of grease, whatever it took to cover the stick being lifted.  When the car would not start, the kid would keep trying.  Their faces would start to go red and he kept trying.  He would come out and check everything he thought he had touched.  The kid would be talking the whole time about how he only did this or that, with the customer adding more bullshit to the story.  As they were both looking around the engine the customer would push the stick back in as he reached across the engine.  He would end the hoax by grabbing the kids hand and asking him if he wiped his hands really well, the kid would insist he had, he would ask the kid if it was a clean rag, and the kid showed him the rag.  The customer told the kid that rag wasn't clean enough, so the kid got a fresh rag wiped his hands well, reached in and the car started right up.  Nobody would let him off of the story until the customer brought his car back in 2 months later.  Somebody would ask the kid if that was the car he had a hard time with, knowing full well he remembered.  The proof of that happened when the kid was going around looking for a new rag so he could start the car.

 

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Sorry Doug those PVC valves had a hose directly to that air cleaner as I described, how else could they pull a vac on the CC?  That valve had a hose that went to the air cleaner so the carb could pull the vacuum.  The air entering the CC was through the oil fill cap which had a mesh screen filter open to the atmosphere on the opposite bank of the V8. I worked on many of those setups. The air cleaner is always in a vacuum when the car is running with a carburetor.  My first car I purchased in 1958 and it was a 49 Ford flat head six. 

http://econofix.com/pcv.html     for reference. 

Edited by wmgeorge64
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18 minutes ago, wmgeorge64 said:

Sorry Doug those PVC valves had a hose directly to that air cleaner as I described, how else could they pull a vac on the CC?  That valve had a hose that went to the air cleaner so the carb could pull the vacuum.  The air entering the CC was through the oil fill cap which had a mesh screen filter open to the atmosphere on the opposite bank of the V8. I worked on many of those setups. The air cleaner is always in a vacuum when the car is running with a carburetor.  My first car I purchased in 1958 and it was a 49 Ford flat head six. 

They did it the same way for decades.  They ran a vacuum line from the base of the carburetor or from the intake manifold to either rocker cover, that had a pcv valve to connect to.  You are simply confusing the vented line that went to the air cleaner.  Think about it, have you ever had the air cleaner off of an engine?  How could it run with that enormous vacuum leak?  There is no vacuum above the air horn on a carburetor.  

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54 minutes ago, Doug_Scott said:

They did it the same way for decades.  They ran a vacuum line from the base of the carburetor or from the intake manifold to either rocker cover, that had a pcv valve to connect to.  You are simply confusing the vented line that went to the air cleaner.  Think about it, have you ever had the air cleaner off of an engine?  How could it run with that enormous vacuum leak?  There is no vacuum above the air horn on a carburetor.  

 

  You have never ran an engine without an air cleaner? 

  

"PCV TO THE RESCUE!!! 

To save the driveways of America, auto manufacturers came up with POSITIVE CRANKCASE VENTILLATION or PCV. With this system, a vacuum is drawn on the engine crankcase from the intake manifold or carburetor base. A valve is put in this line which closes under low vacuum. This enables the engine to have no PCV action when starting, or at low vacuum. When the engine runs, air is sucked through the pcv valve, taking the blowby gasses into the intake manifold, where they are burned. To prevent a vacuum from developing in the crankcase, fresh air is admitted through a special filter. This filter was originally the same "filter cap" that the draft tube used. Later engines have the filter on the air cleaner, usually with a tube leading to one valve cover."

Edited by wmgeorge64
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  • 4 weeks later...

So I will try to help here as I have been tuning using hptuners and see first hand results of using a sealed catch can, vented catch can or free air venting the cc, or utilizing the stock PCV system.

 

Using a sealed can improves performance and longevity like a vented can does but still allows a slight amount of carbon buildup on the valves of a DI engine. I’ve seen the stock pcv system cause preignition due to carbon deposits on the spark plugs and combustion chamber. This obviously hurts gas mileage and performance. When venting the cc to atmosphere and giving the engine a nice treatment of seafoam, the preignition caused by the ingestion of oil vapors disappeared and performance returned. Using a sealed catch can is better than not using any sort of modification at all and worth it from my experiences. I’ve ran my cc vents to atmosphere on all of my vehicles since I’ve started tuning engines and I will continue to do so to keep engine cleanliness and longevity as long as possible.

 

The only reason the OEM uses a pvc system is for emissions purposes and nothing more. If OEM would use some sort of small injector that soaks the intake valves periodically to clean them around service intervals (like the fuel injectors in port fuel injection engines use to do full time) this carbon buildup wouldn’t be an issue for the longevity of the valvetrain and engine performance for the most part.

 

Venting the cc to atmosphere is second best to using a high volume vacuum pump pulling a vacuum on the cc at WOT not recirculating the oil vapor back into the intake tract.

 

I work on race cars all the time and though the tech they use in most of them is nothing new, it’s because the EPA doesn’t care learn how to not hurt the performance of fossil fuel burning engines. I’ve seen engines without emissions equipment produce less harmful emissions than some bone stock vehicles with catalytic converters and a functioning pcv system.

 

Downside to running the little pod filters off the valve covers is misting the top of the valve covers with oil vapor which will collect dust and make a mess with time. Also if you do this, there will be a vacuum leak and DTC if you don’t plug the little port going to the intake manifold from the pcv tube and venting the cc vent under the tb to atmosphere as well as the vents on the fronts of the valve covers. 2c51535aaf85690a29f5360f444c6e5e.jpg

 

 

Sent from my iPhone using Tapatalk

 

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3 hours ago, emaxxer86 said:

So I will try to help here as I have been tuning using hptuners and see first hand results of using a sealed catch can, vented catch can or free air venting the cc, or utilizing the stock PCV system.

 

Using a sealed can improves performance and longevity like a vented can does but still allows a slight amount of carbon buildup on the valves of a DI engine. I’ve seen the stock pcv system cause preignition due to carbon deposits on the spark plugs and combustion chamber. This obviously hurts gas mileage and performance. When venting the cc to atmosphere and giving the engine a nice treatment of seafoam, the preignition caused by the ingestion of oil vapors disappeared and performance returned. Using a sealed catch can is better than not using any sort of modification at all and worth it from my experiences. I’ve ran my cc vents to atmosphere on all of my vehicles since I’ve started tuning engines and I will continue to do so to keep engine cleanliness and longevity as long as possible.

 

The only reason the OEM uses a pvc system is for emissions purposes and nothing more. If OEM would use some sort of small injector that soaks the intake valves periodically to clean them around service intervals (like the fuel injectors in port fuel injection engines use to do full time) this carbon buildup wouldn’t be an issue for the longevity of the valvetrain and engine performance for the most part.

 

Venting the cc to atmosphere is second best to using a high volume vacuum pump pulling a vacuum on the cc at WOT not recirculating the oil vapor back into the intake tract.

 

I work on race cars all the time and though the tech they use in most of them is nothing new, it’s because the EPA doesn’t care learn how to not hurt the performance of fossil fuel burning engines. I’ve seen engines without emissions equipment produce less harmful emissions than some bone stock vehicles with catalytic converters and a functioning pcv system.

 

Downside to running the little pod filters off the valve covers is misting the top of the valve covers with oil vapor which will collect dust and make a mess with time. Also if you do this, there will be a vacuum leak and DTC if you don’t plug the little port going to the intake manifold from the pcv tube and venting the cc vent under the tb to atmosphere as well as the vents on the fronts of the valve covers. 2c51535aaf85690a29f5360f444c6e5e.jpg

 

 

Sent from my iPhone using Tapatalk

 

 

It is very easy to tune an engine that has zero emission controls.  Decades ago I got stopped in my pro street 78 Mustang that I put a 71 boss 351 with a tunnel ram, 2 Carter competition series 750 cfm carbs, high lift long duration camshaft and no catalytics.  The cop sent me to the ministry of environment for emission testing and inspection.  Before going to the test site I brought the car into the shop and made changes to the carbs jetting and metering rods, as well as raised the idle a bit.  I got the emissions down to below max. Car drove like crap.  Car passed both inspection and the 2 specific tests that they could test for back then. 

 

The only thing that should have been looking for was oxides of nitrogen.  Oxides of nitrogen are created by hot combustion.  Race engines kind of depend on high temp in combustion chambers.  Manufacturers have been using EGR systems to help cool combustion chambers thereby reducing oxides of nitrogen. 

 

Your race engines with zero emission controls installed cannot pass the complete emissions test with a 5 gas test machine. 

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A long time ago in a land fa, far away they built single cylinder motorcycle motors and used a device called a 'duckbill'. A thin walled rubber tube with the end formed nearly closed and attached to the crankcase just below the cylinder. When the piston descends air is expelled and when it rises the hose end is forced closed which draws a small vacuum on the crankcase. On the next descent the only thing that could be expelled would be anything getting by the rings. In a well sealed motor this meant that vapor traffic was nearly zero and the tube end stayed fairly dry. When it started to wet the bike down you knew your rings were done. :lol:

 

In a multi-cylinder motor there is one piston rising for everyone falling so the pulsing gets to be nearly zero. Some very low pressure is built during warm up but motors with low leak down rates have nearly zero vapor traffic. 

 

Under WOT there is precious little manifold vacuum at the time when ring leakage is highest. Might even be positive if the plenum is large enough.(NA motors only) Huge vacuum when the throttle is low and ring leakage is near zero which is the case for about 3/4 of the two cycle event even at WOT.

 

Sort of why racers like exhaust Venturi  systems. That could be done on a modern street motor if those were placed after the cats. 

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So in reading all of this...  Is there a simple way to eliminate the introduction of oil into the intake?  Can we simply route the crankcase vent to the air, or to a catch can that would not rely on vacuum?  Just have it go to the can, deposit any oil and vent to the atmosphere?  Same with the vents on top of the heads?

And then simply cap the vacuum line so it's not sucking air or throwing a CEL?

What would be potential problems with this type of setup?  I feel like if pressure builds up in the case, it pushes how the hose into the catch can...  The only drawback might be allowing humidity into the case because the catch can vents to the air and therefore isn't a "sealed system"....So in reading all of this...  Is there a simple way to eliminate the introduction of oil into the intake?  Can we simply route the crankcase vent to the air, or to a catch can that would not rely on vacuum?  Just have it go to the can, deposit any oil and vent to the atmosphere?  Same with the vents on top of the heads?

And then simply cap the vacuum line so it's not sucking air or throwing a CEL?

What would be potential problems with this type of setup?  I feel like if pressure builds up in the case, it pushes how the hose into the catch can...  The only drawback might be allowing humidity into the case because the catch can vents to the air and therefore isn't a "sealed system"....

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1 hour ago, SquireSCA said:

So in reading all of this...  Is there a simple way to eliminate the introduction of oil into the intake?  Can we simply route the crankcase vent to the air, or to a catch can that would not rely on vacuum?  Just have it go to the can, deposit any oil and vent to the atmosphere?  Same with the vents on top of the heads?

And then simply cap the vacuum line so it's not sucking air or throwing a CEL?

What would be potential problems with this type of setup?  I feel like if pressure builds up in the case, it pushes how the hose into the catch can...  The only drawback might be allowing humidity into the case because the catch can vents to the air and therefore isn't a "sealed system"....So in reading all of this...  Is there a simple way to eliminate the introduction of oil into the intake?  Can we simply route the crankcase vent to the air, or to a catch can that would not rely on vacuum?  Just have it go to the can, deposit any oil and vent to the atmosphere?  Same with the vents on top of the heads?

And then simply cap the vacuum line so it's not sucking air or throwing a CEL?

What would be potential problems with this type of setup?  I feel like if pressure builds up in the case, it pushes how the hose into the catch can...  The only drawback might be allowing humidity into the case because the catch can vents to the air and therefore isn't a "sealed system"....

I capped my PCV line to the manifold, not a problem.

 

You can Cap the intake breather tubes and run the Valve cover breathers to the atmosphere, or to an atmospheric catch can or like I did: to the Exhaust with a Crankcase Evacuation System.

 

Its been years and I haven't had any issues whatsoever.

 

You can get a glimpse of my set up in the video explaining how to delete the Vacuum Pump:

 

Edited by VdellaV
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So if I understand this...  I can  run the crankcase vent and the valve cover vents to a catch can that vents to a little pod filter, to prevent anything from getting back into the system, and to help capture as much oil as possible to reduce any mess under the hood...  All 3 lines could be spliced to a single catch can... And then just plug the manifold vacuum line.

This would work, and prevent ANY oil from the crankcase from entering the intake system...

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7 minutes ago, SquireSCA said:

So if I understand this...  I can  run the crankcase vent and the valve cover vents to a catch can that vents to a little pod filter, to prevent anything from getting back into the system, and to help capture as much oil as possible to reduce any mess under the hood...  All 3 lines could be spliced to a single catch can... And then just plug the manifold vacuum line.

This would work, and prevent ANY oil from the crankcase from entering the intake system...

The only way to prevent Oil from returning to the engine is to NOT RETURN ANY LINE to the engine.

 

You can cap and delete the little 3/8 pcv line and just run the two 5/8 Breather Lines to an Atmospheric Catch can.

 

This is exactly how I was running my set up before the Evac System

 

You would need a catch can like this one, that vents the air out of a filter.

 

5/8 Breather lines from the engine go into each fitting and  they vent out of the filter:

PLM-CATCH-CAN-SMALL-V2-2.jpg?v-cache=156

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So I would have 3 lines total, right?  The crankcase vent line, plus one each from the valve covers...  The one going back to the manifold, the vacuum line, gets the cap.

Correct?  I can use my current catch can, where I can simply take the "exit" line that was connected to the manifold vacuum line, and put one of those pod filters on that...

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