[C2] 63 PCV system
Pro
Joined: Jan 2016
Posts: 605
Likes: 199
From: Born and Raised in South Detroit (Windsor) Ontario
Pcv
Thanks Mike,looked at my brass 90* and it does have a smaller hole. On the bottom of said 90 there are 3 letter P set in a circle,does that sound correct?
Ric
Ric
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
Some guys here think that is a standard sized hole in that fitting. 5/16ths or 3/8ths' and then wonder why their car runs rough.
Last edited by MikeM; Oct 26, 2017 at 06:35 PM.
Le Mans Master
Joined: Feb 2012
Posts: 5,407
Likes: 1,216
From: Glen Allen VA
If I'm not mistaken, at least some of the oil fill tubes that the vapors are pulled from have a baffle in them to separate the oil from the air stream. I'll go look here in a minute. Been a long time since I eyeballed an oil fill tube up close. Edit: Based on a sample size of one I had handy, I can't verify the baffle.
In any case, there is not a lot of oil flying around inside the oil fill tube compared to the rear of the block with the crank, cam and lifters throwing oil everywhere.
The post above was simply to point out that the FI intakes used two different directional flows, just like the carb engines.
In any case, there is not a lot of oil flying around inside the oil fill tube compared to the rear of the block with the crank, cam and lifters throwing oil everywhere.
The post above was simply to point out that the FI intakes used two different directional flows, just like the carb engines.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
Did you note that the (later) ones that pull vapors out of the oil fill tube also have a flame arrester in the flow path going in the back of the block? Maybe that tomato can is useful in preventing a backfire from going in the crankcase? Don't know, just a thought but the way the bean counters do business, I'm inclined to believe there was a purpose for it or it wouldn't have been there.
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,270
Under high load or high blowby situations the '64-'65 valveless system may flow "backwards". Crankcase vapors will exit the rear of the block and enter the air cleaner housing, so the liquid vapor separator is still required, and the screen in the air cleaner on carbureted cars serves as a flame arrestor.
Under low to moderate load air flows from the air cleaner to the back of the block and then into the carburetor via the flow restrictor.
FI engines may not have a flame arrestor, and don't really need one because the manifold is not "wet", so a backfire flame can't propagate into the plenum and crankcase.
This system was replaced in '66 with a valve type system, albeit a different architecture than '63, so I guess Chevrolet was not satisfied with the valveless system.
These early PCV systems also had another "problem". The architecture didn't allow good ventilation of the rocker boxes, which is why they redesigned the system to draw fresh air into one rocker cover and exit the opposite rocker cover. This architecture first showed up on the '65 big block and small blocks followed suit beginning in '68.
Duke
Under low to moderate load air flows from the air cleaner to the back of the block and then into the carburetor via the flow restrictor.
FI engines may not have a flame arrestor, and don't really need one because the manifold is not "wet", so a backfire flame can't propagate into the plenum and crankcase.
This system was replaced in '66 with a valve type system, albeit a different architecture than '63, so I guess Chevrolet was not satisfied with the valveless system.
These early PCV systems also had another "problem". The architecture didn't allow good ventilation of the rocker boxes, which is why they redesigned the system to draw fresh air into one rocker cover and exit the opposite rocker cover. This architecture first showed up on the '65 big block and small blocks followed suit beginning in '68.
Duke
Melting Slicks
Joined: Jan 2007
Posts: 2,842
Likes: 622
From: Pasco Florida
Under high load or high blowby situations the '64-'65 valveless system may flow "backwards". Crankcase vapors will exit the rear of the block and enter the air cleaner housing, so the liquid vapor separator is still required, and the screen in the air cleaner on carbureted cars serves as a flame arrestor.
Under low to moderate load air flows from the air cleaner to the back of the block and then into the carburetor via the flow restrictor.
FI engines may not have a flame arrestor, and don't really need one because the manifold is not "wet", so a backfire flame can't propagate into the plenum and crankcase.
This system was replaced in '66 with a valve type system, albeit a different architecture than '63, so I guess Chevrolet was not satisfied with the valveless system.
These early PCV systems also had another "problem". The architecture didn't allow good ventilation of the rocker boxes, which is why they redesigned the system to draw fresh air into one rocker cover and exit the opposite rocker cover. This architecture first showed up on the '65 big block and small blocks followed suit beginning in '68.
Duke
Under low to moderate load air flows from the air cleaner to the back of the block and then into the carburetor via the flow restrictor.
FI engines may not have a flame arrestor, and don't really need one because the manifold is not "wet", so a backfire flame can't propagate into the plenum and crankcase.
This system was replaced in '66 with a valve type system, albeit a different architecture than '63, so I guess Chevrolet was not satisfied with the valveless system.
These early PCV systems also had another "problem". The architecture didn't allow good ventilation of the rocker boxes, which is why they redesigned the system to draw fresh air into one rocker cover and exit the opposite rocker cover. This architecture first showed up on the '65 big block and small blocks followed suit beginning in '68.
Duke
The 64-65 FI system had a flame arrestor between the rear crankcase tube and the air cleaner adapter.
Last edited by Critter1; Oct 27, 2017 at 10:49 AM.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
Over the years, I've pulled the top lid off the FI plenum on four different units that had some miles on them. Two that drew vapors through the back of the plenum through a PCV valve and two that used the restrictor in the front of the plenum. Both designs displayed about an equal amount of dried, coked oil deposits laying on the plenum floor, just below the intake port suggesting that both designs would pull in a little oil.
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