Catch Can with or without PCV? Which is best?

[pbf777]

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.
     

     

[shelbydoug]

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.

[Bob Gaines]

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.

[pbf777]

.......... 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!   

     Scott.

[2112]

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

[Bob Gaines]

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.

[shelbydoug]

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?

[shelbydoug]

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. 

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?

[s2ms]

Wherever you install the PCV it's 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 5/8" from any baffling or filter media. You can use a thicker grommet, probably can't 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.

[shelbydoug]

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? 

[shelbydoug]

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.

[Side-Oilers]

one more

Thanks Doug!  I will try it.