COCHEV
1/2 ton status
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what are the small tube pieces with the 45 degree cuts on them for? is there a picture of this set up installed?
CK5
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77K5. The IronMaiden...9/2 headed for Blazer Bash 20!
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jack of all trades build, overland, dunes, rocks, trails
what are the small tube pieces with the 45 degree cuts on them for? is there a picture of this set up installed?
So run the two breather/separators from the valve covers to a common breather mounted to the firewall then? No need for a vacuum source from the engine to draw vapors out?
there has been much debate about the pcv system on the big blocks. i run a pretty simple, stockish set up with the one line from the carb to one valve cover and the other from the valve cover to the air box (i run a stock air box w/ stock cai) it seemed to help with oil consumption over the breather/filter on the pass side.
your idea seems pretty cool, but maybe over killbut then again, mine is a straight up beater compaired to your build....
Hey thanks Jason....
so that one line from the carb to the valve cover, does that have PCV in it, or just open tubing?
and what is stock cai?
The pictures show a system based on the venturi principal, and is a header sourced crankcase evacuation system.
On the right are the breather/separators that are old chrysler type valve cover items.
going left is the check valves that mount to the pipe which has to be put in the header collector at a 45* angle to get the venturi effect. This creates a vacuum at rpm to draw out vapors and create a better ring seal in the cylinder.
Many racers are using a vacuum pump now to create more vacuum in the crankcase to help with ring seal.
This may help better than my explanation:
They should always be installed in a no pressure area of the exhaust, and downstream of mufflers/cats to prevent contamination.
COCHEV
1/2 ton status
wow, i've never seen a set up like that. very cool.
cai= cold air intake. basically i have the stock air box and snorkle tube to the firewall. i swapped both my rigs back to this from the open air elements they had when i bought them. i noticed no drop in power and get a lot longer life out of my air filters...
cai= cold air intake. basically i have the stock air box and snorkle tube to the firewall. i swapped both my rigs back to this from the open air elements they had when i bought them. i noticed no drop in power and get a lot longer life out of my air filters...
COCHEV
1/2 ton status
oh, and the one from the carb to the valve cover does have the little pvc valve thingy. open tubing from the other cover to the air box.
i've never seen the exhaust used to crank ventalation.
why is all this crank ventalation so critical with big blocks?
i've never seen the exhaust used to crank ventalation.
why is all this crank ventalation so critical with big blocks?
From the couple BBC's (older carb types) I've had, they like a little bit of oil, and I want to minimize this by keeping it out of the intake charge.
I also want to prevent any water from getting into the engine from a simple valve cover breather that would be open to the atmosphere.
Therefore the reasoning behind my (probably) overthinking of the subject.
I also want to prevent any water from getting into the engine from a simple valve cover breather that would be open to the atmosphere.
Therefore the reasoning behind my (probably) overthinking of the subject.
COCHEV
1/2 ton status
that makes sense. are you building your rig for mud and deep water?
my 454 uses some oil, but at this point i don't know if its a 454 thing or simply a getting older thing.
however, i used to have the 8.1 liter and with only 30-40k on it, it would use a quart between oil changes. just wondering why the big blocks do this and the 350s don't seem too...
my 454 uses some oil, but at this point i don't know if its a 454 thing or simply a getting older thing.
however, i used to have the 8.1 liter and with only 30-40k on it, it would use a quart between oil changes. just wondering why the big blocks do this and the 350s don't seem too...
I would recommend setting up the PCV system as was factory (PCV valve in one valve cover and a clean air tube to the air cleaner in the other. This way has worked the best for the last 50 years.
well, most marine apps just run an open tube from each vc up to the flame arrestor... when a motor develops some blowby, the arrestors need to be cleaned every so often...
you could install an oil/air seperator between the PCV and your vac source if your concerned about keeping the intake charge clean...
Fred_M1010
1/2 ton status
x2
If you don't use vacuum to lower the pressure inside the engine, it will be more prone to leak oil.
And if you use the hose to the air cleaner instead of a breather, you'll have no problem with water.
If you get water in the air cleaner, you've got bigger problems anyway
hmmm good points Scott and Fred....eventually I'd like to make the induction at the cowl area, to keep water out to a greater extent. I like to play in the water.
So maybe I'll run those two breathers on the valve covers, one to the air cleaner, and one to a pcv on the base of the intake/carb......for now
Paul, you still have me thinking on this one
I'm thinking the front/upper part of the valve cover position would be better than toward the rear to make these holes in my covers.
thanks for the input guys.
So maybe I'll run those two breathers on the valve covers, one to the air cleaner, and one to a pcv on the base of the intake/carb......for now
Paul, you still have me thinking on this oneI'm thinking the front/upper part of the valve cover position would be better than toward the rear to make these holes in my covers.
thanks for the input guys.
yeah, I would definitely run a pcv style system on a vehicle... like i said, you could add an oil/air seperator to the system if need be... maybe come off the pcv over to a seperator on the firewall, then over to your vac source... source side, either off the cleaner or maybe a filter source up high on the firewall depending on what your air filter setup is...
Thanks Paul, I'm still leaning more towards that concept. That way I could tell if any oil accumulates also, and if so, that would have been oil in the intake system.
So now, how big of an oriface can I use for a vacuum source?
What size oriface's are available in PCV's?
My thinking is the bigger the vacuum source the more vapors to be scavenged out of the crankcase.
So now, how big of an oriface can I use for a vacuum source?
What size oriface's are available in PCV's?
My thinking is the bigger the vacuum source the more vapors to be scavenged out of the crankcase.
most pcv's i've seen are usually 1/2"
your right, they use a sliding plunger against a spring....now I member!
The oriface was in my Vette's Crankcase evac system.
It used a fixed oriface from the intake manifold breather tube to the carb.
Gotta keep my junk straight. They seem to blend together sometimes.
The oriface was in my Vette's Crankcase evac system.
It used a fixed oriface from the intake manifold breather tube to the carb.
Gotta keep my junk straight. They seem to blend together sometimes.
If you're getting oil in the little breather inside the air cleaner then your system isn't working correctly OR you have too much crankcase pressure (bad rings) and the system can't handle the excess crankcase pressure.
Scott, that fact came from 2 different vehicles, both 100K+ mileage, but not really oil burners, maybe a quart every 1000 or so. Just seemed like everytime I'd check the air filter, the housing would be wet around the area of that crankcase breather filter that goes in the side of the A/C housing. I kept the PCV's clean, and generally was up on the maintenance side of things with them. Both using factory air cleaners too.
So that would indicate there was high crankcase pressure forcing airflow in reverse of the way the system is supposed to function right?
So that would indicate there was high crankcase pressure forcing airflow in reverse of the way the system is supposed to function right?
chulisohombre
1/2 ton status
i didnt mean have a open breather on the valve cover.but it does need a clean air source to come into the engine.so it needs some kind of breather maybe farther up on the firewall than the air intake and a breather on it.then the pcv in the other side going into the accumulater seperator and finally into the carb at full vaccuum.the reason the stock breather gets some oil accumulation is that when you give it gas and there is enough vaccuum,the pcv closes and the some air pressure is back vented out of the breather and some particulates in the gases are going to eventually look like oil is coming back up the breather tube.thats about the only way to do it correctly.i may be wrong but if you put dual breathers into the vaccuum canister (oil accumulater) it would create more air pressure inside the engine than relieving them and getting rid of them.im not sure how many pounds of pressure the carb can potentioly pull in vaccuum but that may create more oil consumption with the extra pressure.they have ran the stock setup for 50+ years but it can always be improved upon.
gotta take time for enjoying the summer
It don't last real long in MI, so I've been working more on my camper, getting ready for a weeks vacation at Silver Lake with the kids, and my Dad...wish I was taking the Iron Maiden, but I'll be taking the Jeepster up this time. I've had some work to do on the camper, and some mods to the Jeepster, so it can take more than 2 at a time. Also been getting the Fatboy ready for some mileage....doing the 30000 mile service finally to get ready to go for a ride to the Mackinaw Bridge and Sault Ste. Marie shipping locks.
The ride of choice for this trip:
It don't last real long in MI, so I've been working more on my camper, getting ready for a weeks vacation at Silver Lake with the kids, and my Dad...wish I was taking the Iron Maiden, but I'll be taking the Jeepster up this time. I've had some work to do on the camper, and some mods to the Jeepster, so it can take more than 2 at a time. Also been getting the Fatboy ready for some mileage....doing the 30000 mile service finally to get ready to go for a ride to the Mackinaw Bridge and Sault Ste. Marie shipping locks.
The ride of choice for this trip:
