Pcv-positive crank venalation - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**67sss** · 05-01-2003, 12:16 AM

I 've seen some pics of engine and have noticed some have breather/filler caps on both valve covers, sometimes on the same end, I thought motors were to breath internally and that the breather/filler caps were to be opposite of each other. Just a thought.

Longhorn Man · 05-01-2003, 12:20 AM

The best way to set them up (IMO)is a breather on one side, and a PCV valve on the other.
It just sucks when you start getting a little blow by and it starts to puke on your purdy chrome valve cover.

Hooter · 05-01-2003, 12:22 AM

Thats why every chevy has rags under the seat

mikep · 05-01-2003, 12:39 AM

Old chevies had only breathers on the engine or a combination of breathers and road draft tubes. Neither one of which did a very effective job of ventilating the crankcase. Modern open and closed PCV systems allow filtered dry clean air to be drawn through the crankcase and with minimal negative affect on the air fuel when the PCV valve is in good condition. Aside from the emissions benefits this cuts down on the amount of condensation that forms inside the engine and reduces the amount of sludge formation inside the engine. Tear open a 200,000 mile chevy engine from 1959 sometime and you'll see what sludge formation is all about. It also cuts down on the carbolic acid formation in the crankcase which extends the service life of the oil and reduces engine wear. The only real time that PCV isnt a good idea is when you are on the cutting edge of detonation as suspended oil droplets in crankcase gasses can agravate detonation problems in very hi performance motors.

71-longbed · 05-01-2003, 02:21 AM

i have pcv on the driver side and a tube that runs from the valve cover to the high rise throat on top of my q jet .....what is that tube call .....and what is a flame arrestor ??? just curious if these work ...ive had no problems ....

**67sss** · 05-01-2003, 01:57 PM

I have a 60's series 327 in my truck ,which B4 I rebuilt it had a internal tube in the valley. Now I have 1 breather filler on the front drivers side, and the valley tube(?) still there. At the time of the rebuild this was a stock 12:1 vette engine, it is now a 10:1. Am I getting enough air flow internally?.......getting my thinking from my brain to my fingers to type what I mean isn't one of my gifts, if ya know what I mean..

71-longbed · 05-01-2003, 02:27 PM

i hear ya man ...fingers dont operate like they use to

67cst · 05-01-2003, 03:15 PM

i have a mid 60s 327 in my 67, it doesnt have any breathers on the vavle covers

73stepside · 05-01-2003, 06:27 PM

take out one of the breaters and put in a pcv valve. pretty easy. you should be getting enough air flow but the only engines that see breathers on both sides of the engines are usually race engines that barely see the bottom side of the rpm scale. dual breathers prolly won't hurt but if you want to change over, it's pretty simple.

05-01-2003, 12:16 AM	#1
67sss Registered User Join Date: Nov 2002 Location: Mt. Vernon, WA.. Posts: 2,324	Pcv-positive crank venalation I 've seen some pics of engine and have noticed some have breather/filler caps on both valve covers, sometimes on the same end, I thought motors were to breath internally and that the breather/filler caps were to be opposite of each other. Just a thought.

05-01-2003, 12:22 AM	#3
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	Thats why every chevy has rags under the seat __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

05-01-2003, 12:39 AM	#4
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	Old chevies had only breathers on the engine or a combination of breathers and road draft tubes. Neither one of which did a very effective job of ventilating the crankcase. Modern open and closed PCV systems allow filtered dry clean air to be drawn through the crankcase and with minimal negative affect on the air fuel when the PCV valve is in good condition. Aside from the emissions benefits this cuts down on the amount of condensation that forms inside the engine and reduces the amount of sludge formation inside the engine. Tear open a 200,000 mile chevy engine from 1959 sometime and you'll see what sludge formation is all about. It also cuts down on the carbolic acid formation in the crankcase which extends the service life of the oil and reduces engine wear. The only real time that PCV isnt a good idea is when you are on the cutting edge of detonation as suspended oil droplets in crankcase gasses can agravate detonation problems in very hi performance motors. __________________ No truck :-(

05-01-2003, 02:21 AM	#5
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	i have pcv on the driver side and a tube that runs from the valve cover to the high rise throat on top of my q jet .....what is that tube call .....and what is a flame arrestor ??? just curious if these work ...ive had no problems .... __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

05-01-2003, 01:57 PM	#6
67sss Registered User Join Date: Nov 2002 Location: Mt. Vernon, WA.. Posts: 2,324	pcv I have a 60's series 327 in my truck ,which B4 I rebuilt it had a internal tube in the valley. Now I have 1 breather filler on the front drivers side, and the valley tube(?) still there. At the time of the rebuild this was a stock 12:1 vette engine, it is now a 10:1. Am I getting enough air flow internally?.......getting my thinking from my brain to my fingers to type what I mean isn't one of my gifts, if ya know what I mean..

05-01-2003, 12:20 AM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	The best way to set them up (IMO)is a breather on one side, and a PCV valve on the other. It just sucks when you start getting a little blow by and it starts to puke on your purdy chrome valve cover.

05-01-2003, 02:27 PM	#7
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	i hear ya man ...fingers dont operate like they use to __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

05-01-2003, 03:15 PM	#8
67cst i love summertime Join Date: Jul 2002 Location: Kelowna BC Posts: 4,303	i have a mid 60s 327 in my 67, it doesnt have any breathers on the vavle covers __________________ 1967 shortbox stepside Chevy, 365 hp 327, th400. GLOVE BOX LIGHTS FORSALE, click link for info http://67-72chevytrucks.com/vboard/s...d.php?t=273724

05-01-2003, 06:27 PM	#9
73stepside Registered User Join Date: Feb 2002 Location: Moore OK 73160 Posts: 974	take out one of the breaters and put in a pcv valve. pretty easy. you should be getting enough air flow but the only engines that see breathers on both sides of the engines are usually race engines that barely see the bottom side of the rpm scale. dual breathers prolly won't hurt but if you want to change over, it's pretty simple. __________________ 04 GMC Sierra RCSS 70 CST LWB 04 HD Sportster 1200 Custom



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