2: Does anyone have a recommendation on which catch can to purchase and any hoses? with considerations given to make sure that the outlets in the breather and the catch can can be connected with the same size hoses/lines
I have never purchased or installed a catch can so any other recommendations or relevant info would be useful
I'm going to be going down the same path soon, I have the same breather, and am installing carbs.
I'll give a couple thoughts, and maybe there will be an answer for you within my thoughts.
1st you have to decide whether you want your vapors from the crank case to be ingested back into combustion or whether you want to just vent to atmosphere. Obviously with the original fuel injection set up you are re ingesting those vapors, and the catch can on a normal modern fuel injected car is there so that the oil is not being injected but basically only the air. If you are running carbs, as you know, they are really not set up to be re ingesting that vapor either with or without a catch can.
I suppose with a customized intake manifold you might be able to do this. I have heard of some people making a custom exhaust so that the vapors are brought into the exhaust stream by vacuum.
Personally I don't think all of that is worth it.
So with all of that said, in my opinion all you really need to do is get a hose that goes up high enough above the crankcase vent that you pictured. You can then put a filter on top of that. With no real world experience so far on this particular motor with this issue, I would guess that by just having a bit of length of hose and a filter on top is all that is going to be needed. The pressure can escape through the hose out through the filter but the oil vapor is not really going to want to travel uphill up a hose. I think that the stock breather that you pictured works pretty well as a separator anyway so honestly I don't think it's going to take that much length of a hose.
Basically by doing that you are duplicating what thousands and thousands of American V8's have done for decades and decades by having just a tall open breather cap on a valve cover. It is venting to atmosphere, there is no provision for it to be sucked back into the carburetor.
I'm sure at least one will come in here and tell us that won't work. Lol.
But that is my plan. I am going to get a 90゚ hose (probably silicone) that will fit on that breather and then get a filter to go on top of that hose. I will make it as tall as possible without hitting the carbs. I will have to revisit it and see how much length I can get away with, if it's not very much length I might bring the hose more somewhat horizontal and then try to raise it off to the side of the engine near the transmission.
As to what hose size just measure that nipple that is coming out of the breather. Don't measure the flared part but the main diameter of the tube.
Mine is about 1.25" or about 33 mm. Assuming yours is the same.
There are some breathers in that size range, we will have to get creative on which one to buy and how to attach it to a hose. Most of the time those breather filters do not have an inside tube included with them they have a rubber tube that is sized by their ID so that they can go on to a metal tube. And basically there will be 2 choices, the gauze type filter like a K&N or the chrome domed metal breathers that you will see often on a V8 valve cover. The completely metal ones will not need to be cleaned like the gauze ones, but then again if the breather is working right and it is up high enough, we really shouldn't be getting much vapor all the way to that filter anyway.
As for the block off plate that you mentioned, in my opinion I am not really a fan of decreasing the size of the breather tube so much from what it was stock. That block off probably would work fine for a car that is still using fuel injection and has the other end of a catch can going back into the intake manifold where it has enough vacuum to pull the pressure and vapor through that smaller tube fitting. I don't think you are doing any favors for yourself on a carb set up when you have no vacuum pulling on that small diameter tube. And remember, the smaller the diameter of the tubing, the velocity going through it will increase. That will help push oil up further.
Thanks for taking the time to right a comprehensive reply my friend!
While searching through the forum I did see some people that had did do exactly what you describe but none were on a carb'ed motor. With my setup I definitely do not had enough room to go vertically from the breather as there isn't enough room to go high enough. Because of this a catch can might aesthetically look better than a hose coming off the stock breather at at 30 degree angle to the right with the filter on it. Unless the carbs can hide the filter a little. I'll look into the for sure. When I bought it I was advised by the builder of the car that a catch can would be a good idea. I currently has a K&N gauze filter clamped onto the end of the stock breather and it has a good amount of oil saturation. I am also trying to pinpoint an oil leak at the same time.
I'm like you, I care about the looks of things on my engine, but function always comes before form. If it doesn't work, then it doesn't matter what it looks like.
I am glad that you mentioned that your breather filter is oily.
That tells me that we definitely need to have a higher routed hose.
I may very well still end up with a catch can, but I will most likely make one myself, keeping the hoses all large like original. Again, I don't believe in making a restriction if there's no vacuum to compensate.
Do as you wish, but if it was my engine, I would get that blow-by gases back into the intake where it belongs. Having it vent to the atmosphere is just wrong in so many ways. Sure it was done back in the day, but back then dumping oil in the ground was ok too.
There are many ways to make it work and have it look good. It just takes some planning. Mann [Provent] makes an aftermarket separator that works great and has designed the oil drain so it does not have to be dumped.
Again, do as you wish but you could design a system that 'looks' right and functions properly. I'm certainly not a green person but if I can spend a little time and money to make the world better, why not. I know it may be a fashion statement, but those little breather filters look bad.
today i pulled off the breather to measure for hosing. The hose will need a 1 1/8 inch inside diameter hose to attached the the stocker breather outlet with a hose clamp.
with the ID of the hose being quite large. I have not been able to find a catch can with the same size inlets. most are 1/2" or 3/4" NPT so it will have to be reduced. Becasue of this I'm still thinking that the breather plate from techtonics Tuning might be the easiest way to go. I have read that the reduced size of the hosing my cause some problems i dont understand this. Can anyone explain?
Also, if I was to not vent out from the catch can, how/where would the return line be run to for the gases?
Again, unless you are drastically modifying the DUAL CARB manifold, you will have no source for vacuum to pull gas/vapor through a catch can.
The dual sidedraft manifold is just not made for that.
Because of this, you are not wanting the block off plate with its smaller hose setup. Without vacuum, smaller hose means more restriction.
That block off plate is ideal for those running Fuel Injection with a catch can.
Can it be done? Maybe on the longer runners of the Pierce manifold or maybe others if you plumb in a fabricated "log" to each runner.
Certainly not an option for my very short runners.
Not sure about you, but my car is a sunny Sunday driver, driven to car shows and an occasional back roads toy. I don't stress about a little bit of oil smell.
I bought a Cheena puke tank off ebay - mounted to right fender in front of EDIS coils
It "helped" but was only venting to atmos
Enter the DBilas carb plenum with internal filter
In the top rear of the plenum you see a red hose clamp - there is a vacuum nipple there on the plenum this connects to the clear hose on the puke tank.
I made an alu plate for the breather hole in the block. It has a fitting to the black hose on the puke tank.
IT is so much better with the vacuum pulling, oil consumption has dropped to an acceptable level.
Nice setup. I may go with something like that eventually, but an air box is definitely down the road for me right now. I've got a world of stuff to figure out, that will come later. Are you using a vented catch can or non vented?
How much fluid are you getting in your can, say, every 3k miles or so? Reason I'm asking is I'm curious how much vacuum you're seeing from in front of the carbs.
It has never been a lot of oil in the puke tank, especially with the vaccum pulling now. I empty it less than once/year. I probably drive 1500-2000 miles a year. I dont have numbers but at steady running it is sufficient and I am running Schrick 276 cams which actually run very smooth on carbs compared to CIS.
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