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Discussion Starter · #1 ·
I've got a question. My 454 has two odd things on its valve covers, that Im not sure what they are, or at least which are which. The driver side has a large cylindrical thing with a fat hose that plugs into the bottom of the aircleaner (aftermarket edelbrock). The passenger side has an L shaped valve thing that is connected to the same vacum fitting on the back of my carb that the brake booster goes too. What are these things? Do I need them? Or can I clean up the compartment some by replacing them both with breathers. Or one with a breather and one with an oil fill cap. Will changing this around adversely or positively affect performance?

What do you guys suggest?


Eric
 

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Eric,
Leave it as it is! The hose that hooks into the bottom of the air cleaner draws fresh air into the crankcase, while the other device is the PVC valve which "meters" the flow of crankcase vapors into the combustion chambers. This process helps burn off harmful crankcase contaminants and also keeps them from being released into the atmosphere. The system, as designed, works very well as long as it is maintained. Usually, the carb is calibrated for the addition of this system. You won't gain anything by taking it off and could possibly cause yourself problems by doing so...problems like leaking seals, etc.

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MalibuJerry350
Original owner '70 Chevelle.
540,000+ miles on car.
My Chevelle: http://hometown.aol.com/erie614/myhomepage/index.html
 

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The valve thingy on the pass side is the PVC valve and you need it. It should be changed with each tuneup. Put new stuff on and it will look ok. The canister on the left side is the crankcase breather and you also need one. You can replace it with an aftermarket chrome one if you want, but you also need this to accomodate the evacuation of the engine by the PVC valve. Don't know your emmisions requirements but CA may require you to keep the "closed" system that breathes through your air cleaner for the visual part of the test. Neither hurts performance.
 

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I agree , keep it working as is, with one exception. If you can find a good place to hook the brake booster to its own source of vacuum, do so. Having the booster hooked in with the pcv valve will reduce the vacuum signal to the booster.
 

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the pcv(positive cranck case ventilation) valve(the one that plugs into the vaccum off the carb) draws pressure out of your motor and draws the oily vapor into your carb to reburn. The tube that goes into your breather is were it draws air from. Dont get worked up and afraid about burning lots of oil, if everything is working well it aint much and if the system is working well then why fix it right? But in answer to your ? you could just stick breathers in both hole and any pressure would just bleed off. It wont help your performance at all unless your system is having problems.

Sorry I read the post and took off 1/2 through the respose so when I got back and posted it is just redundant info.

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Philip Blackburn
Primer black 69 velle (far from done)
my motors done...
454-60 over
iron merlin rec port heads
Compcams promagnum rockers roller cam
.646int.653exst 280/286 w/110separation
10.25 compression
RPM airgap eagal rods
ARP bolts and studs
will run an auto
ACES # 04287

[This message has been edited by ratlover (edited 03-29-2001).]
 

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Discussion Starter · #7 ·
Ok, so the PCV valve stays.....but can I replace the breather that plugs into the air cleaner with its own open element one with no ill affects? I just really like the look of the K&N open element breather caps. replacing the crankcase breather with one of those would be the same thing right?
 
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