to pcv or not pcv....
#1
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Car: 91 Camaro RS
Engine: 350 bored .030 carbed
Transmission: t5
Axle/Gears: 3.08
to pcv or not pcv....
i was wondering if it would hurt/help anything if i got rid of the PCV on my LO3 and threw some nice looking valve cover breathers on there and just plugged the PCV line to the throttle body... also i never can get a straight answer on this, what exactly does the PCV do... is it for emissions? or does it serve a bigger purpose and should just be left alone?
#2
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Car: '86 Camaro SC
I'd leave the PCV. It basically prevents sludge buildup down in the crank case and other places. It puts a nice vacuum seal on the rings too.
Leave it.
Leave it.
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Car: 91 Camaro RS
Engine: 350 bored .030 carbed
Transmission: t5
Axle/Gears: 3.08
dammit, lol..... than why do you see alot of cars with just breathers on the valve covers if its bad? im not argueing, just asking..... would i at least be able to get rid of the stock ugly breather filter on the passenger back vc?
#5
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Car: 85 Z28
Engine: LG4 modified
Transmission: 700R4
The vapours floating around the crank case turn acidic after a time. You'll have to change your oil about once a week to keep up. It's not worth it, and you can get a nice looking chrome breather.
#6
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Car: 91 Camaro RS
Engine: 350 bored .030 carbed
Transmission: t5
Axle/Gears: 3.08
ok sweet.... but im still curious why alot of ppl dont run PCV's if hurts the motor that bad?
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#9
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Car: 84 Z28
Engine: 357
Transmission: TH-350C
Axle/Gears: 3.43
Pop in a PCV, They do nothing but good. For a couple bucks you can get a fancy breather to put on the other valvecover, which has to be done for fresh air to enter the crankcase.
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Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
my chrome topped K&N one shows the red filter paper, *and* is chrome, nothing looks better than that.
Definately a good thing to have.
Definately a good thing to have.
#11
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i could be wrong but i think the pcv valve is a one way valve that helps clear unburnt gases from the crank case (where they could ignite) for a street car i wouldnt run with out one for very long.........tao
#12
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yes it pulls vapors out of the crankcase
the pop in breather filter thingies are used for the return
filtered return
into the crankcase
the pvc is where the vapors are pulled out\
you need it
leave it
68 was the first year for this closed system
in 67 and older all it was was a huge open vent in the rear of the block into the air
it has nothing to do with emissions, nor is it an emissions system
if you dont have it it will cause problems in your engine over time
the big ugly breather on the vc was originallpy not there and instead was a return tube connected to the air cleaner assembly and had a little filter in it, this si where the clean filtered air was returned into the crankcase to make up for the vaporous air being sucked out(and burned) of the crankcase in the driver side VC
the pop in breather filter thingies are used for the return
filtered return
into the crankcase
the pvc is where the vapors are pulled out\
you need it
leave it
68 was the first year for this closed system
in 67 and older all it was was a huge open vent in the rear of the block into the air
it has nothing to do with emissions, nor is it an emissions system
if you dont have it it will cause problems in your engine over time
the big ugly breather on the vc was originallpy not there and instead was a return tube connected to the air cleaner assembly and had a little filter in it, this si where the clean filtered air was returned into the crankcase to make up for the vaporous air being sucked out(and burned) of the crankcase in the driver side VC
Last edited by Randy82WS7; 08-10-2006 at 08:54 PM.
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Car: 1988 Trans Am GTA
Engine: 350 4BBL
Transmission: 700R4
Axle/Gears: 3.27
What happens when the PCV is plugged off and this idle air is lost, is the carb idle circuit must be turned leaner. No big problem except the throttle plates must be opened to make up for the loss of air. You hear about people drilling holes in the throttle plates. If the carb is any good the main jets start to flow when the throttle is moved off of the idle position due to the increased air flow. What you wind up with is the idle circuit still flowing (because the plates are still closed) and the main jets dripping at idle due to the increased air flow. This will "wash out" the rings from the raw gas removing the oil at idle. Not to mention the vapors trapped in the crankcase condensing and forming sludge.
The humble PCV valve is more complicated than it seems also. It is not simply a check valve or an orfice that won't clog up. The valve is held almost closed at idle by engine vacuum since blowby is minimal. When the output of the engine increases the vacuum drops and the valve opens more to handle the increased blowby. Ain't that neat?
The reason you see multiple breathers on race-only engines is the thin rings (1/16") that they have to use for high rpm produce so much blowby that it overwhelms the PCV system. Watch tractor-pull setups and you will see 2 plumes of smoke coming from pipes at the bottom of the engine to handle this blowby.
End of PCV systems 101.
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