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The Cars => Replicas and Tribute => Topic started by: Side-Oilers on April 20, 2021, 10:36:48 PM

Title: Catch Can with or without PCV? Which is best?
Post by: Side-Oilers on April 20, 2021, 10:36:48 PM
My Kirkham 427, with a fresh aluminum 482 engine, is getting a bit of blow-by on the passenger side during deceleration, from approx 3000 rpm and up.   The engine is great other than that.

I installed an M/E Wagner adjustable PCV, connected to passenger side valve cover, and to a vacuum port under the carb.  I tuned it for the optimum vacuum, etc.

The other valve cover has a period-style Ford breather.

I'm now thinking I need a catch can.   So, is it better to run a closed system that retains the PCV, or an open system with no PCV, and vent(s) on the catch can?

I've read that the vented can scenario is the race car type (not really necessary on my street driven Kirkham) and will emit a fuel or oil vapor when the car is idling, like at a traffic light.

I'd appreciate anyone's thoughts, opinions, best plumbing ideas, recommended hose sizes, and anything else.  8)
Title: Re: Catch Can with or without PCV? Which is best?
Post by: s2ms on April 21, 2021, 12:22:22 AM
I'm using a Bob's Machine oil separator on my 66. Otherwise stock PCV valve and closed breather setup. Works great and fits with no modifications, the bracket is attached to one of the export brace bolts. Probably overkill at this point as I finally was able to fabricate a baffle that is working well, originals were removed to fit roller rockers/polylocks, but it still does catch some oil so keeping it installed for now. I used repop PCV hoses and cut to fit.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 21, 2021, 07:48:44 AM
My Kirkham 427, with a fresh aluminum 482 engine, is getting a bit of blow-by on the passenger side during deceleration, from approx 3000 rpm and up.   The engine is great other than that.

I installed an M/E Wagner adjustable PCV, connected to passenger side valve cover, and to a vacuum port under the carb.  I tuned it for the optimum vacuum, etc.

The other valve cover has a period-style Ford breather.

I'm now thinking I need a catch can.   So, is it better to run a closed system that retains the PCV, or an open system with no PCV, and vent(s) on the catch can?

I've read that the vented can scenario is the race car type (not really necessary on my street driven Kirkham) and will emit a fuel or oil vapor when the car is idling, like at a traffic light.

I'd appreciate anyone's thoughts, opinions, best plumbing ideas, recommended hose sizes, and anything else.  8)


I am running this setup and it's my opinion (sometimes I even argue with myself though) that it is more of a skimmer then anything and is only going to have a percentage of effectiveness.

I find very little oil in my "catch can", mostly an inch or two of water.

So really, it's anyones guess how well it really works?


Maybe look for a catch can from a current tight emissions car and see if there is internal switching on them.

Thinking about it, I think there is an electrical connection to the one on my Audi and I need to investigate why.

They are most likely on the car to protect the cat from further contamination from oil deposits?


Good question but I don't know the answer to your question. Just speculation since I'm only as far along as you are.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 21, 2021, 10:05:49 AM
I found that the best setting on the Wagner is using the under 10 inch method. It completely shuts off the valve at idle and results in higher idle vacuum.

I went from 12 inches to 16-17 inches at idle on the same 236@.050 cam. That's all in the pcv system. I'm very happy about that.

That was basically just changing the spring in the Wagner valve.


I don't think that you need an open breather in the valve cover. The air cleaner is essentially functioning that way already. Take off the top of the aircleaner while the engine is idling. Look at the water vapor coming out of the connection. That thing is open already.

Try closing up the open valve cover. See what the results of that are? If you really want to be scientific, you could hook up a vacuum gauge somehow to the pcv system. You don't want more then about 12inches otherwise you'll suck in things like the crank seals which I would predict to be a bad thing.

The header scavaging system provides something like only 6 inches but most racers use it these days, but talk about sucking oil out of the covers and making a mess? That's it.

The suction point is too low and will encourage siphoning oil out of the valve covers.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: pbf777 on April 21, 2021, 11:58:33 AM
.................... a bit of blow-by on the passenger side during deceleration, from approx 3000 rpm and up. 


      I gather with your concerns of valve cover attachments that your reference of "blow-by" is as observed from the valve cover breather?  Not from the tail pipe?      :-\


Quote

I installed an M/E Wagner adjustable PCV, ....................................  I tuned it for the optimum vacuum, etc.


     "Optimum vacuum"?  A control setting for the implied "ideal" operation?  Really!  And how is this "ideal" actually going to be established "in-the-field" and with which parameters for observed function or result?    ???

       Now I'm aware of perhaps (depends on the application) an observed loss in the vacuum value (change in manifold pressure) within the induction system when a P.C.V. valve is instituted, and a at times real concern for this effect (particularly on a carburetor) but?           

       In my opinion this is a perfect example of creating an implied need, then with a product (gadget) to solve no real issue, but in the price range that will lead to many a "what-if' or "why-not" sale!  But it is a cool billet gizmo anyway!    ::)

      Scott.
     
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 21, 2021, 12:38:15 PM
.................... a bit of blow-by on the passenger side during deceleration, from approx 3000 rpm and up. 


      I gather with your concerns of valve cover attachments that your reference of "blow-by" is as observed from the valve cover breather?  Not from the tail pipe?      :-\


Quote

I installed an M/E Wagner adjustable PCV, ....................................  I tuned it for the optimum vacuum, etc.


     "Optimum vacuum"?  A control setting for the implied "ideal" operation?  Really!  And how is this "ideal" actually going to be established "in-the-field" and with which parameters for observed function or result?    ???

       Now I'm aware of perhaps (depends on the application) an observed loss in the vacuum value (change in manifold pressure) within the induction system when a P.C.V. valve is instituted, and a at times real concern for this effect (particularly on a carburetor) but?           

       In my opinion this is a perfect example of creating an implied need, then with a product (gadget) to solve no real issue, but in the price range that will lead to many a "what-if' or "why-not" sale!  But it is a cool billet gizmo anyway!    ::)

      Scott.
   

Not to defend the indefensible but in my case I wanted a pcv that fully closed at idle.

That is the identified issue. The Wagner was the selected solution.


It wasn't as large an issue with the 2-4's but the IR with the Webers on the Cleveland was only giving me 11-12 inches.

Could I have run open breathers and have them dripping all over the valve covers and running on the headers? Sure. How is that a solution?

I could cook a pizza on top of the hot engine too but I don't see that as successful or desirable multitasking and in addition, the dripping valve cover vents would ruin the pizza.

I wouldn't even do that to a TVR.  ;)


The Wagner isn't just a pretty face gizmo, it's a highly engineered gizmo. How do you know you need it? How do you know you need 1,000hp?


If you want to run a car on a track these days a catch can is required for the pcv AND the radiator overflow, so it isn't exactly a solution searching for a problem.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: s2ms on April 21, 2021, 12:59:48 PM
I am running this setup and it's my opinion (sometimes I even argue with myself though) that it is more of a skimmer then anything and is only going to have a percentage of effectiveness.

I find very little oil in my "catch can", mostly an inch or two of water.

So really, it's anyones guess how well it really works?

Yes, how well it works is the big question. FWIW, I recall reading That Ford Performance uses the Bob's Machine separator on the GT350 Track Attack cars.

I haven't tried the Wagner valve but did talk with the one of the owner's about my situation, super nice and helpful guy. Ended up not getting it because my situation looks under control with the new baffle. I believe what little oil is still getting into the can is due to my Lunati cam as well, ~11 in at idle, 239@.050, I bet the Wagner would clean that up using the under 10 inch method. Looks like a solid product, IMO if you can measure the difference in oil collection it's at least a gizmo that works as intended.

When I first started to evaluate how well the new PCV baffle design was working, I was using 2 of the cheapo Steeda cans in parallel, seen in the pic below, to measure oil collection. The first can always had ~2x more oil than the second. The Bob's Machine can picks up more than both of the Steeda cans together.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 21, 2021, 01:16:31 PM
At the risk of repeating myself, repeating myself, my issue with every Ford small block I've owned is that the "factory" pcv system ALWAYS siphoned oil out of the valve covers and into the intake manifold. Always.

Now take that, the requirement of a track catch can and looking for more idle vacuum for the brakes without a vacuum pump, this all got mixed into an attempt at a COMBINED SOLUTION.


After seemingly going through every pcv  part number conceivable, the Wagner became a logical and economical solution.

I eventually stopped blaming China for poor quality pcv's and realized that by design, NONE completely closed at idle. Not even the L88 version with that lumpy factory idle.

What I DISCOVERED with the Wagner is that if I followed instructions the darn thing didn't completely close at idle but "discovered" by chance, if I changed the spring to the 10 and under instructions, all of a sudden it did, and I had mega vacuum available.


So that's my story and I'm sticking to it and yes, don't even ask the question, at times I do think I'm delusional? My oldest son is the kindest. He just says, "you have too many parameters open at the same time. How can you possibly understand what is going on at any one moment". Bless him! ::)
Title: Re: Catch Can with or without PCV? Which is best?
Post by: s2ms on April 21, 2021, 03:11:55 PM
At the risk of repeating myself, repeating myself, my issue with every Ford small block I've owned is that the "factory" pcv system ALWAYS siphoned oil out of the valve covers and into the intake manifold. Always.

And......the Cobra intake design makes matters worse since that PCV system dumps directly into the intake right next to cylinder #4, so it get's hammered.

At least that should not be an issue with the OP's concern since his system is connected to a vacuum port under the carb, the PCV siphoned oil should be distributed more or less evenly between all cylinders, in theory anyway.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 21, 2021, 03:57:59 PM
At the risk of repeating myself, repeating myself, my issue with every Ford small block I've owned is that the "factory" pcv system ALWAYS siphoned oil out of the valve covers and into the intake manifold. Always.

And......the Cobra intake design makes matters worse since that PCV system dumps directly into the intake right next to cylinder #4, so it get's hammered.

At least that should not be an issue with the OP's concern since his system is connected to a vacuum port under the carb, the PCV siphoned oil should be distributed more or less evenly between all cylinders, in theory anyway.

Well I think that the height of the intake port is significant. The higher it is the less it SHOULD siphon.

I think of two exceptions to that thought or maybe where that just didn't matter.


My 68 302 had a spacer under the carb to give the pcv a higher connection. No dice. Sucked it in.

Parents 76 302 Granada. Same type of spacer under the carb. Sucked the pan dry (under waranty).


A side thought here as well. There are people that will argue on the small block, the FE and the Cleveland, that there were significant bottom end failures due to lack of oil.
They blame everything under the sun for them. NONE of them take into consideration this major fault of siphoning oil.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Side-Oilers on April 21, 2021, 04:04:57 PM
Thanks one and all...

My M/E Wagner is set up for 8-inches of vacuum at idle, and about 10 at 2000 rpm. 

Here's a pix of my setup.   I was still running the back of block vent then. I now have it capped off.  Also, this pix is before the carb base plate was installed.

Doug, as you mentioned...is the carb base plate where the PCV hose is connected my biggest problen?

I'm also till thinking about running a catch can.    I'd like anyone's thoughts and experience in running a closed system (no breathers on the catch can) vs an open system (with breathers.)
Title: Re: Catch Can with or without PCV? Which is best?
Post by: SFM5S000 on April 21, 2021, 04:09:48 PM
Well hereís my venting setup. Because I run Weberís, I have no provisions for a PCV. My only option or should I say the direction I took was to run twin breathers plumbed to a vented Catch Can. The can was mounted without drilling a single hole.
Hereís a birds eye view which can be easily duplicated in a cobra engine bay regardless of induction system.

Cheers,
~Earl J

Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 21, 2021, 04:40:25 PM
Thanks one and all...

My M/E Wagner is set up for 8-inches of vacuum at idle, and about 10 at 2000 rpm. 

Here's a pix of my setup.   I was still running the back of block vent then. I now have it capped off.  Also, this pix is before the carb base plate was installed.

Doug, as you mentioned...is the carb base plate where the PCV hose is connected my biggest problen?

I'm also till thinking about running a catch can.    I'd like anyone's thoughts and experience in running a closed system (no breathers on the catch can) vs an open system (with breathers.)

If you ask me after describing the symptoms that you are concerned about, I think that spacer connection is as the "Ghost Busters" might say, "is spook central". LOOK at the way the hose drops down below the oil level in the valve covers with the engine running. That's siphoning oil right there. That hose needs to be elevated.

You can see, even with Earl's post, that we are all dealing with similar situations.


I explained my observations of what my catch cans are doing. I can tell you that on my Audi TT, the catch can to that group is a PITA and is doing the same thing of largely collecting water and some oil droplets. However, the thing is connected differently away from the valve cover possibility of siphoning out oil.


Earl. What started this therapy session for me (working out these types of issues is therapy to me although I just heard a new term referring to me. What does "Bat s hit" mean? Is that good?)


Here's the pictures of my Pantera system. You can see the vacuum plumbing but the collector of those tubes is a fuel log under the heat shielding. More importantly, look at the catch can, plumbed to the valve cover and that runs to the "vacuum log".

I relocated the pcv port into the valve cover also as you might notice?


So here is a IR Weber system with a pcv, so don't say you can't do it.

Webers dump a lot of fuel because of this, "let's mash the throttle" mania that comes over you just because you can.

That eventually does a job on the top compression ring because of the cylinder washing. IF EVER there was an engine that would welcome more piston ring sealing BECAUSE of a pcv system, it's a Weber system like this?

Does it actually work? Maybe? ::)

OH LOOK, you have one just like it? Small world? ::)


These pics are mostly for Earl. You can plumb the Webers for vacuum and then add pcv to that system.
If you don't want to drill the intake, fabricate spacers for under the carbs that you can add a vacuum port to.
Necessity is the mother of invention.  ;D
Title: Re: Catch Can with or without PCV? Which is best?
Post by: pbf777 on April 21, 2021, 05:24:25 PM
Not to defend the indefensible but in my case I wanted a pcv that fully closed at idle.

Could I have run open breathers and have them dripping all over the valve covers and running on the headers? Sure. How is that a solution?


     Often even the most incapable function will find usefulness, somewhere, somehow, and prove a capable, usefully ally!  But I am attempting to reference the most commonly encountered scenarios one can expect to encounter.

    And I perhaps understand your intention wishing to have the vacuum loss to the P.V.C. system defeated at idle, this apparently to aid in carburetor function (a concern mentioned previously), or perhaps just for better vac. booster effect but what is it that you expect from the P.V.C. system at higher engine speeds?

    Oil carry-over control from the valve covers(s) or other orifice openings from the crankcase to atmosphere are not in the realm of responsibility of the P.C.V. system though some arbitrary value is had particularly at idle (I guess not in your case though) and perhaps low engine revolutions, but as this system has limited flow capacity and the by-pass sums from particularly combustion pressures quickly increase with load and R.P.M.'s this does outstrip this potential possibility.


Quote
If you want to run a car on a track these days a catch can is required for the pcv AND the radiator overflow, so it isn't exactly a solution searching for a problem.


    Why would and what would a "catch-can" requirement do in the P.V.C. plumbing circuit as this system amounts to a sealed pathway from crankcase access (valve cover is common to American V8's) to that of the low pressure manifold area meaning that nothing is going to be escaping or leaking on the ground (the concern for "catching the oil), but rather any oil carry-over is going to routed thru the combustion process leading to only fume out the tail pipe?  On the opposite valve cover of the typical "closed crankcase system" (again as is common to American V8's) again a sealed plumbing pathway is provided from the air cleaner canister to the crankcase area for the purpose of first presenting an atmospheric source for the P.V.C. system to ultimately access as this is drawn thru the crankcase and secondly where when the blow-by (or some prefer "blow-down") sum becomes to great for the P.V.C. plumbing to handle, there will be a reversal in flow direction with the excess volume is then vented to the, again lower than atmospheric pressure, air cleaner canister to be still ingested by the engines' combustion process and out the tail pipe.  This presenting a "closed crankcase ventilation system", what's to "catch"?        :o

     Now the engine may present whether with or without the presents of a P.V.C. valve, an "open" (to atmosphere) crankcase breathing access, now this does obviously require a "catch-can" and so may some rulings from some race organizations on the prior "closed system", but I am just posing the statement for thought of.........WHY?       :-\


     And also realize that it is not the purpose or intention to actually utilize the P.V.C. system to create a vacuum sum on the crankcase area or as a substitution for the intention of say a dedicated crankcase vacuum pump.      ;)

Quote
I wouldn't even do that to a TVR.  ;)

     Does this statement qualify as automotive racism?   I think I'm offended!      ::)

     Scott.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: s2ms on April 21, 2021, 05:41:04 PM
I'm also till thinking about running a catch can.    I'd like anyone's thoughts and experience in running a closed system (no breathers on the catch can) vs an open system (with breathers.)

Personally I would install one of the cheap catch cans, like I show in reply #6, just to get a quantitative idea of how much oil is getting through the PCV and into the intake via the spacer connection. You can plumb it in using stiff hosing and you won't have to attach it to anything, the hose will keep it in place. You're welcome to borrow my setup if you like, just let me know.

Don't know if it would help but I think in your situation you can connect the PCV to the rear of the intake and take the valve cover siphoning out of the equation. There are kits for FE's like this:

https://www.ebay.com/itm/284265816138 (https://www.ebay.com/itm/284265816138)

I don't have any experience with the open catch cans but there are lots of choices if you want a PCV connected oil seperator. I chose the Bob's Machine unit due to it's very good reputation and haven't been disappointed.

Dave
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 21, 2021, 05:45:55 PM
I'm also till thinking about running a catch can.    I'd like anyone's thoughts and experience in running a closed system (no breathers on the catch can) vs an open system (with breathers.)

Personally I would install one of the cheap catch cans, like I show in reply #6, just to get a quantitative idea of how much oil is getting through the PCV and into the intake via the spacer connection. You can plumb it in using stiff hosing and you won't have to attach it to anything, the hose will keep it in place. You're welcome to borrow my setup if you like, just let me know.

Don't know if it would help but I think in your situation you can connect the PCV to the rear of the intake and take the valve cover siphoning out of the equation. There are kits for FE's like this:

https://www.ebay.com/itm/284265816138 (https://www.ebay.com/itm/284265816138)

I don't have any experience with the open catch cans but there are lots of choices if you want a PCV connected oil seperator. I chose the Bob's Machine unit due to it's very good reputation and haven't been disappointed.

Dave

ALL excellent questions to ponder of which proportional thought will be applied to.  ;)

Here's one for you. Do you have to sleep only on the right side of the bed? ::)
Title: Re: Catch Can with or without PCV? Which is best?
Post by: s2ms on April 21, 2021, 09:26:05 PM
Here's one for you. Do you have to sleep only on the right side of the bed? ::)

Well yes, the correct side!  :o
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Side-Oilers on April 21, 2021, 09:47:14 PM
Thanks guys.  Great advice.


Should I keep the PCV in the valve cover, or install it in the "rear of the manifold" location, which is currently capped off?


The Bob's Machine catch cans look like a good product.  I'll try it. Thanks.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: 2112 on April 22, 2021, 12:05:05 AM
Impressive that a pristine Autolite cookie cutter valve cover cap has been drilled for a PCV connection.

 ;)
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Side-Oilers on April 22, 2021, 12:14:26 AM
I'm using a Bob's Machine oil separator on my 66. Otherwise stock PCV valve and closed breather setup. Works great and fits with no modifications, the bracket is attached to one of the export brace bolts. Probably overkill at this point as I finally was able to fabricate a baffle that is working well, originals were removed to fit roller rockers/polylocks, but it still does catch some oil so keeping it installed for now. I used repop PCV hoses and cut to fit.

Thanks for the photo.  My Kirkham doesn't have that much space to mount the Bob's can, but I can hopefully fab something that will work.  I now understand the idea about having the can higher than the carb vacuum port.  8)
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Side-Oilers on April 22, 2021, 12:18:28 AM
Impressive that a pristine Autolite cookie cutter valve cover cap has been drilled for a PCV connection.

 ;)

It's not NOS.  ;D   

Drake, I think.  I like the look of it better than a bunch of other options on the market.   Plus it says "Autolite"  Cool  8) 8)
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 22, 2021, 06:54:04 AM
I'm using a Bob's Machine oil separator on my 66. Otherwise stock PCV valve and closed breather setup. Works great and fits with no modifications, the bracket is attached to one of the export brace bolts. Probably overkill at this point as I finally was able to fabricate a baffle that is working well, originals were removed to fit roller rockers/polylocks, but it still does catch some oil so keeping it installed for now. I used repop PCV hoses and cut to fit.

Thanks for the photo.  My Kirkham doesn't have that much space to mount the Bob's can, but I can hopefully fab something that will work.  I now understand the idea about having the can higher than the carb vacuum port.  8)

Personally I'm not completely sure of what the exact combination is to break the siphoning effect. Everything mentioned seems to help some

My experiences at the moment are on the small block and the Cleveland. My 428 is still on the engine stand but one of the subjects discussed on the 67 GT500 engine is why was the pcv hose plumbed to the bottom of the air cleaner base rather then the vacuum port on the intake?

I speculated that perhaps this "issue" of oil siphoning isn't imaginary and the quick fix was the hose relocation? Maybe that is in effect a stroke of genius?  ::)

I'm thinking that maybe before emissions wasn't such a big issue, some oil in the intake wasn't a bad thing? Thinking of the original Ford system of using those rubber umbrellas on the valve stems, it seemed to be just a system of reducing the quantity of oil to the valve stems rather then eliminating it?

Title: Re: Catch Can with or without PCV? Which is best?
Post by: 2112 on April 22, 2021, 10:22:09 AM
Impressive that a pristine Autolite cookie cutter valve cover cap has been drilled for a PCV connection.

 ;)

It's not NOS.  ;D   

Drake, I think.  I like the look of it better than a bunch of other options on the market.   Plus it says "Autolite"  Cool  8) 8)

I had no idea Drake made them. It looks good. Kudos to the machinist who cut the hole without  fubarring it.

I bought two real NOS caps. Don't ask how much.   :o
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Bob Gaines on April 22, 2021, 11:32:57 AM
Impressive that a pristine Autolite cookie cutter valve cover cap has been drilled for a PCV connection.

 ;)

It's not NOS.  ;D   

Drake, I think.  I like the look of it better than a bunch of other options on the market.   Plus it says "Autolite"  Cool  8) 8)

I had no idea Drake made them. It looks good. Kudos to the machinist who cut the hole without  fubarring it.

I bought two real NOS caps. Don't ask how much.   :o
Don't feel bad about your purchase just yet. The one that Drake sells in ether black or chrome is the the 70's style cap with a hole and not the closed emission cap like 67 thermactor cars used. FYI the one's used on 67's typically were plain and not marked with Autolite .
Title: Re: Catch Can with or without PCV? Which is best?
Post by: 2112 on April 22, 2021, 12:01:23 PM
Impressive that a pristine Autolite cookie cutter valve cover cap has been drilled for a PCV connection.

 ;)

It's not NOS.  ;D   

Drake, I think.  I like the look of it better than a bunch of other options on the market.   Plus it says "Autolite"  Cool  8) 8)

I had no idea Drake made them. It looks good. Kudos to the machinist who cut the hole without  fubarring it.

I bought two real NOS caps. Don't ask how much.   :o
Don't feel bad about your purchase just yet. The one that Drake sells in ether black or chrome is the the 70's style cap with a hole and not the closed emission cap like 67 thermactor cars used. FYI the one's used on 67's typically were plain and not marked with Autolite .

Ahh,

I do feel better now.  ;D
Title: Re: Catch Can with or without PCV? Which is best?
Post by: pbf777 on April 22, 2021, 01:48:20 PM
Should I keep the PCV in the valve cover, or install it in the "rear of the manifold" location, which is currently capped off?


     The answer is: it depends!   Aesthetics aside, although every engineering attempt should include this consideration, I would advise on an FE mounted in a modern Cobra to have two "open" breathers mounted, one to each valve cover, of a type with baffling consideration for resisting oil loss to the exterior, and the P.V.C. valve inserted into the rear intake manifold breather opening also with the required baffling to impede oil entry into this plumbing.  Although this does provide a certain sum of symmetry, it's functional in that first as indicated previously the plumbing is routed uphill from the valve to the entry to the manifold which also as mentioned previously should be under the carburetor presenting particularly the oil contamination in the plenum area thereby dividing this sum among the cylinders and not the presentation into a singular inlet runner.

     In this layout initially at idle and low engine revolutions with reduced load the air flow routing enters the crankcase thru the breathers mounted to the valve covers, being one in each cover increases the available area reducing the velocity and drawing or shall we say flushing the unappreciated by-products of combustion fume and water condensation from both internal sides of the engine toward the P.V.C. valves' central mounting.  This presenting access to the crankcase thru the intake manifold valley cover is an area well shielded from oil throw-off from rapidly moving components.  But understand not immune as we currently have a 427 T.P. mounted on our dyno in which the assembler (not us!) failed to install the gasket for sealing between the tin valley pan and intake, in short order of operation one has a swimming pool of oil accumulating on top of the cover pan.

     As the engine increases in speed and load the blow-by sums greatly increase, soon to the point beyond the flow capacity of the P.C.V. plumbing and now these excessive sums are emitted from the "open" valve cover breathers, and this is the happening that creates the greatest incident of oil escapage and the point of need of typically as defined an "oil catch can".   Again this makes for sound intention as with the area of two "open" breathers velocity is reduced (vs. having only one), and other than oil directly thrown up the pipe (evidence of poor baffling) it is this velocity rate that effects the weight of the oil carried in the air stream and thru the plumbing, and as not to nitpick terminology, your not actually "siphoning the pan dry" as in a straw stuck in you soda can.  The breathers mounted high on the engine also aid in the separation of oil as the atmosphere being evacuated is emanating in path from lower in the crankcase where the heat and turbulence is greatest and the bulk of the mixing of the oil in the atmosphere takes place here and with the required lifting of this heavy mixture enroute to the valve cover mounted breathers much of the oil is permitted the opportunity to drop-out even before it becomes a concern for a reasonable attempt to baffle your breather system in an attempt to preclude the remainder escaping.

      The P.V.C. valve installations' greatest perceived value, in your street driven Cobra, is to reduce the obnoxious fume emanating from the breathers, this generally noted particularly with the engine (oil) hot, and say when at idle stopped at a traffic light, this can even perhaps escalate to the point of presenting a not so pleasing cloud about your vehicle that may not only be odifferous but not present the best presentation for your vehicle.  And yes, there is the benefit of "less" oil escapage and this rather messy presentation upon opening the hood, or if permitted even to the point of dripping on the ground, with the joking statements that your car is marking its' territory every were it's parked.  But again in reality the bulk of the oil carry-over whether external or in the plumbing, particularly of the "closed" venting systems, takes place when your on the throttle, and this is beyond what a properly intentioned P.V.C. system is designed to cope with.

      With a track car, I would eliminate the P.V.C. plumbing, then along with the valve cover breathers, utilize the rear manifold mounting for another crankcase breather outlet.  If permitted reasonably baffled to open breathers work best; sometimes you just can't improve on simple!  If plumbing to catch cans(s), as stated previously mount the reservoir(s) as high as possible, route the plumbing up-hill, particularly as closer to the point of the mountings on the engine (example: in the photo presented in reply #11, the driver side breather hose fitting is pointed in the worst way, down), and use the largest possible (reasonable) plumbing lines and fittings (again, (and he's going to hate me!) in reply #11, this is a minimal size hose in plumbing, but perhaps acceptable on a well sealed small block) as this reduces the velocity allowing the heavier oil mist to drop-out in the line, and if it's downhill to the valve cover, the oil will just drip back into the engine where it belongs.  Its' best to be diligent at keeping the oil out of the plumbing rather than trying to figure out what to do with it once it's here.   ;)

      The problem with most of these cute, billet "bling-bling" catch-cans is that they lack enough internal area to create the velocity reduction required to make them function, and not enough effort in the baffling to make up for this, but perhaps often incorporating something that looks like a filter element(?) which it is implied "separates" the oil from the atmosphere, which it will to some degree, or is it that with the restriction created by this element, particularly once saturated, oil that contacts it is rather infused back into the air stream?  But we already have some previous statements made where they have found minimal remnants of anything, so how well is this working?  Or, was it really needed to start with, so how good does it really need to be?  And then if it were to capture any real volume they lack any capacity for storage, which further defeats their abilities.  Also, if a track car with any great singular on track duration time intended, plumb the catch can canister drain back to the engine (oil pan?) as if you are "siphoning" the oil out of the engine, it will also be automatically flowing back in and not draining the pan.   ::)   

     Scott.

     
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Side-Oilers on April 22, 2021, 04:22:56 PM
^^^ Scott, that is an excellent explanation of the process and the benefits/downsides of PCV vs no PCV.   

When I bought the car, it had only a breather on each valve cover, and on the back of the manifold. No PCV system. This was with the pre-rebuild aluminum FE with 482 c.i.

It ran well on Willow Springs, and aside from pushing some oil out of each valve cover breather and onto the headers, it seemed okay.

On the street, however, it gave off oil smell when at a stoplight.  (Again, this was with No PCV.)


With the rebuilt aluminum 482 (now 483 c.i.) the same breathers and the same No PCV gave heavier smoke/odor on decel (than before rebuild) as I described in my original post.  Much more of both on the right side...thus that's where I chose to mount the M/E Wagner PCV valve in attempt to mitigate the problem.

But, I have learned from your posts that the downhill flow of the PCV to the vacuum port is probably a big source of the problem.


So, I've been monkeying around it, as described, with some gain, but it's not even close to my liking. 

The engine only has about 500 miles on it.  Any thoughts about a ring in the right bank not being fully seated?

If so, what I do, aside from taking the engine apart, to fix it?  Drive it hard for a bunch of miles and hope it seats?


I have just ordered the Bob's Machine catch can that others have recommended as being high quality and effective. 

Running larger diameter hoses for slowing the velocity makes good sense.

I will use that setup, with the PCV mounted at the back of the intake, going into the catch can, and then routed correctly to the front-vacuum-port spacer plate under the carb. A good quality breather on each valve cover will be also employed. 

I'll hopefully be able to get to that install within a couple of weeks, and I will post on how it's working.

Thanks again to everyone who has helped on this topic!  I think I'm better edjumacated now.  ;)
Van
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Bob Gaines on April 22, 2021, 04:50:37 PM
Here are some pictures of the historic configuration of the competition 427 done on a CSX 4000 car . In this scenario the high mounted catch can is mounted high on the firewall . Threaded inserts are in the backside of the can and it is bolted from the passenger side. Vent from intake to the can ,another down low to drain can oil buildup back to pan and the last has hose attached to vent away under the car. The cans started life as gas cans for old style mowers and other small engine applications. This is a historic type setup like used back in the day . Even though it is improbable that oil could get done the final vent tube given the configuration in a measurable amount the venting to the road would be considered a no no by todays open track rules. It would have to be routed differently . This is not meant to be a solution to your dilemma but it is meant to give ideas to possible adapt to your situation so that you don't have to have the out of character (for the car) pvc plumping/catch bottles and what not . I think a 55 year technology style car is better suited with items that don't stand out as from another era when you can help it . If you can't help it so be it . Hopefully it will give some useful ideas . Just my opinion others have theirs.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 22, 2021, 05:05:37 PM
I like that tank. That's cool. I remember those on lawnmowers! Yikes! Ebay or Craigslist? Now they're gonna' be hot!

You can probably solder one up out of copper tubing and make it look like that?


With all due respect to exactly which gizmo tank to select, it has a lot to do with which car you are working on and where you can fit it in "gracefully". I just found that vertical tanks fit better in my applications.

The Daytona Coupes had the engines lowered in the chassis about one inch. Could you do that to a BB Cobra? If you can't get the tank any higher, lower the river, I mean the engine?
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Bob Gaines on April 22, 2021, 05:15:06 PM
I like that tank. That's cool. I remember those on lawnmowers! Yikes! Ebay or Craigslist? Now they're gonna' be hot!

You can probably solder one up out of copper tubing and make it look like that?


With all due respect to exactly which gizmo tank to select, it has a lot to do with which car you are working on and where you can fit it in "gracefully". I just found that vertical tanks fit better in my applications.

The Daytona Coupes had the engines lowered in the chassis about one inch. Could you do that to a BB Cobra? If you can't get the tank any higher, lower the river, I mean the engine?
Yep if you can find a tank that is how they are done . The tanks have been hard to find for a number of years now. My post was specifically addressing the Kirkham Cobra application of the OP.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: pbf777 on April 22, 2021, 05:32:48 PM
In this scenario the high mounted catch can is mounted high on the firewall . Threaded inserts are in the backside of the can and it is bolted from the passenger side.

 I think a 55 year technology style car is better suited with items that don't stand out as from another era when you can help it . If you can't help it so be it .  Just my opinion others have theirs.


     Yes, this is where we have mounted the tanks before also, as it provides for a high mounting, for simple straight forward pluming, has generally proven to be available area, though if already utilized whatever is there can be relocated, and almost as important, with the proper selection of canister and plumbing it can provide an aesthetically reasonable representation of what one would expect "in-period" as Mr. Gains pointed out.       :)

     Rather than some, just to shinny "bling-bling" import car kiddie crap!    ::)

     Scott.
     

     
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 22, 2021, 07:46:25 PM
As far as the oil drain back from the "catch can" into the oil pan. My canton has a 3/8npt plug in the right side pontoon. Right below my catch can.

Initially I considered a simple drain back tube. When I discovered that every time I ran the car, essentially I would get about an inch and a half of water in it, I thought that would not be a good idea.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Bob Gaines on April 22, 2021, 07:59:35 PM
As far as the oil drain back from the "catch can" into the oil pan. My canton has a 3/8npt plug in the right side pontoon. Right below my catch can.

Initially I considered a simple drain back tube. When I discovered that every time I ran the car, essentially I would get about an inch and a half of water in it, I thought that would not be a good idea.
If the water is the result of condensation it will not make any difference because it is coming from the oil galley anyway regardless of if you had a catch can or not. Besides it will evaporate with the high temp of the oil like it normally would if you didn't have a catch can. If the water is the result of something other what is normal given the heat cycle then that is different.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: pbf777 on April 22, 2021, 08:37:01 PM
.......... I discovered that every time I ran the car, essentially I would get about an inch and a half of water in it, .
If the water is the result of condensation it will not make any difference because it is coming from the oil galley anyway regardless of if you had a catch can or not. Besides it will evaporate with the high temp of the oil like it normally would if you didn't have a catch can.


     This is another reason to be sure you have provided adequate breathing capability to the crankcase ventilation system one chooses to create as for if not, yes the water will evaporate into the atmosphere available when heated, that is to it's saturation point anyway, but unless that saturated atmosphere is removed form the crankcase, as it cools after shutdown, the water drops out and condenses on the cooler interior surfaces such as the interior of the valve covers where it is often witnessed.     ;)

     And this would not provide a good environment within the crankcase over time!  I have even seen instances where engines were in an environment of high humidity (I'm in Florida) where they were operated frequently but not for durations lengthy enough to cook-off the moisture, but rather acquire it, to the point where the indicated oil level rises on the dip-stick as the water accumulation in the oil sump displaces the oil upward (remember water is heavier the oil) and the engine ends up starved oil but drowned in water!  Doesn't do much for the bearings!    :o

     Scott.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: 2112 on April 22, 2021, 11:35:59 PM
Might find something adaptable here;

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2060353.m570.l1313&_nkw=vintage+lawnmower+gas+tank&_sacat=0
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Bob Gaines on April 23, 2021, 12:39:02 AM
Might find something adaptable here;

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2060353.m570.l1313&_nkw=vintage+lawnmower+gas+tank&_sacat=0
If someone wants to try their hand at making one using the the round type long like what was used back in the day then the bare metal one I showed a picture of is sitting on my shelf as a extra. PM me if interested.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 23, 2021, 06:45:15 AM
As far as the oil drain back from the "catch can" into the oil pan. My canton has a 3/8npt plug in the right side pontoon. Right below my catch can.

Initially I considered a simple drain back tube. When I discovered that every time I ran the car, essentially I would get about an inch and a half of water in it, I thought that would not be a good idea.
If the water is the result of condensation it will not make any difference because it is coming from the oil galley anyway regardless of if you had a catch can or not. Besides it will evaporate with the high temp of the oil like it normally would if you didn't have a catch can. If the water is the result of something other what is normal given the heat cycle then that is different.

In my case, adding an oil drain back is a solution in search of a problem.

I think of my catch can as more of a skimmer then anything else and the fact that I have no oil in it is likely an indication that I have the siphoning under control or even solved.

Adding water to the oil pan is not a good idea and is likely a doomsday device for the bearings.

So if it isn't broken, don't fix it.


I think that the Off Highway booklet showing the Boss 302 valve covers with drain backs to the oil pan was the seduction/eye catcher here but those were attempts at solving a different issue.


I wouldn't be surprised if I eventually experience some indication of some oil in the intake under hard deceleration, but I haven't as of yet. Vacuum is at it's highest level at that point. So I probably am not running hard enough yet?

I personally prefer braking to using the transmission as a decellerant. I've killed more clutches with using the transmission to slow the car then anything else. "Brakes are cheaper then transmissions", Brock Yates once wrote.


If you have some oil in the intake unless you are causing a spark plug misfire/fouling situation or you are contaminating a cataleptic converter, exactly what harm is it doing?

A hard cooked oil build up on the top of the valves or that part of the valve stem isn't desirable but that seems to come from worn valve guides with lousy stem seals?
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 23, 2021, 10:26:46 AM
I'm using a Bob's Machine oil separator on my 66. Otherwise stock PCV valve and closed breather setup. Works great and fits with no modifications, the bracket is attached to one of the export brace bolts. Probably overkill at this point as I finally was able to fabricate a baffle that is working well, originals were removed to fit roller rockers/polylocks, but it still does catch some oil so keeping it installed for now. I used repop PCV hoses and cut to fit.

Thanks for the photo.  My Kirkham doesn't have that much space to mount the Bob's can, but I can hopefully fab something that will work.  I now understand the idea about having the can higher than the carb vacuum port.  8)

If you use the manifold pcv adapter and the gas can collector, you have minimized the plumping and made it look period correct-ish! I like that idea in a Cobra.

Then you can go back to the carb base plate for vacuum and it should eliminate the potential for siphoning?
Title: Re: Catch Can with or without PCV? Which is best?
Post by: s2ms on April 23, 2021, 03:47:14 PM
Wherever you install the PCV itís important to make sure the valve bottom is not touching, or even close, to anywhere oil can accumulate and get sucked in. I discussed this at length with one of the Wagner owners and he felt that was really important, IIRC he said at least 5/8Ē from any baffling or filter media. You can use a thicker grommet, probably canít see it in the first photo I posted, but I use 2 o-rings under the valve to raise it. In my case, the nice thing is if I want a totally stock look it only takes a few minutes to remove the catch can and replumb everything stock.
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 27, 2021, 09:41:54 AM
Try one of these Moroso pcv grommets. It will help some.  ;)


Going over my notes here, I actually picked up some idle vacuum after I pressure tested the "catch can" and found that it was leaking pretty bad. Even with an o-ring. I also was trying some 1.7 rocker arms and when switched back to 1.6, all issues flew away with the flying monkeys.

I went through several of the tanks to find a good one. They leak around the cap bolts.


In addition, I can't testify as fact that the Wagner valve is completely closed at idle. I'd have to test the entire system with a vacuum gauge somehow in line there which isn't worth the effort.

I do have some water vapor showing at the connection to the air cleaner base idling so it looks like it's open some? Wagner says 1in open at idle.

Just adding this in attempt to be scientific here which doesn't really seem possible in my case? "Too many parameters open" and I keep seeing the flying monkeys, so?  ;)
Title: Re: Catch Can with or without PCV? Which is best?
Post by: shelbydoug on April 27, 2021, 10:02:09 AM
one more

No one noticed that the Cleveland valve covers don't normally have any access holes on the right side? Hum. Not very observant. :o
Title: Re: Catch Can with or without PCV? Which is best?
Post by: Side-Oilers on April 27, 2021, 07:18:21 PM
one more

Thanks Doug!  I will try it.