pcv filter location

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pcv filter location

Postby jim327monza » Sun Feb 26, 2017 3:05 pm

On the factory breather/air filter set up the filter for the pcv is located in the breather but out side the air filter. due to the limited space I an using an open style 15" oblong air cleaner with no provision for the pvc filter. Can I mount the pcv filter inside the air filter? I am talking about putting a hole in the bottom plate and putting a factory style pcv filter inside the footprint of the air filter. I know that it would need to be sealed to prevent unfiltered air from entering the carb.
Thanks, Jim H
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Re: pcv filter location

Postby cjbiagi » Sun Feb 26, 2017 4:23 pm

I have a open element 14" air cleaner and it has a provision in the base for the PCV hookup. Although I am not using it since I just have a breather/filter in the passenger side valve cover it would basically be exactly as you are asking about. Since your hookup would be inside the air filter element (filtered air) you should be able to just connect a hose from there going to the opposite valve cover that the PCV is installed in. You would not need a additional filter since you are already in a filtered area.
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Re: pcv filter location

Postby jim327monza » Mon Feb 27, 2017 8:08 pm

Ok, filter location solved(thanks Clyde). Now for the pcv valve. I am assuming that the one for the 4.3 in the car now will not work for the 69 327 that will replace it(l-79 cam z28 hi rise intake, 600 vacuum seconders 041 heads 9:1 cr ) . My starting point should be the the 69 327/350 4brl camaro . From reading up on this I know that the wrong one can cause problems from bad idle to too lean or too rich fuel mix.Any one with experience or thoughts? And I though that this change would be simple!
Thanks Jim H
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Re: pcv filter location

Postby cjbiagi » Mon Feb 27, 2017 9:06 pm

I remember doing a lot of research many years ago on this. I forget exactly which PCV I ended up selecting but I may have the info at home, I can check in a day or two when I get home. Basically, you want to match one for a similar size engine and vacuum level that you have. A high performance engine making less intake manifold vacuum needs a differently calibrated valve than a stock engine. Are you using a press in PCV that goes in the valve cover? Something like a Fram FV178 may work well. This is designed for a 1971 HP350cid engine. PCV valves are pretty inexpensive so you could try a few and see what works best.
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Re: pcv filter location

Postby chevyart » Mon Feb 27, 2017 11:56 pm

cj that PCV valve should be just about perfect. last year on speedtalk, the guys recommended a PCV from a 1970 Z_28 hi-po engine for a high horse musclecar engine. Art
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Re: pcv filter location

Postby jim327monza » Wed Mar 01, 2017 8:45 pm

Clyde, I plan on using the factory set up as much as possible, so yes it will be the push in valve. If my memory serves me the last year of the factory l-79 327 was 68 so i will see what cars had the L-79 (Camaro Chevlle ect) compile a list of pcv valves and start with the most common one and work from there. AC Delco Cv746c is one that seems to pop up for the HO camaro.
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Re: pcv filter location

Postby chevyart » Thu Mar 02, 2017 12:25 am

the l-79 cam is a very mild cam. only has a .447 lift with just a little overlap. any 327 chevy engine PCV valve will work OK. your engine should have a nice high vacuum reading so i cant imagine any idle problems because of an incorrect PCV valve. some of the hotrodders put a petcock in the line to regulate air to custom tailor your idle. art
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Re: pcv filter location

Postby cjbiagi » Thu Mar 02, 2017 9:52 am

The PCV valve is designed to flow very little at idle (high vacuum). So, its basically a matter of picking one with the correct spring to operate properly for whatever vacuum level your engine is producing. Same principal applies to a vacuum advance modulator. If the valve is designed to open at say 14" and you engine only produces 12" of vacuum at idle then it is going to be flowing more at idle than it should. High vacuum opens it, low vacuum opens it......that is why high performance engines use a different valve. So picking one from that application should put you in the ballpark.
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Re: pcv filter location

Postby chevyart » Fri Mar 03, 2017 3:08 pm

CJ thanks for the picture on PCV valve at work. Art
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Re: pcv filter location

Postby MonzaRacer » Sun Mar 05, 2017 8:36 pm

There is an adjustable one out there. http://mewagner.com/?p=444
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Re: pcv filter location

Postby cjbiagi » Tue Mar 07, 2017 10:14 am

I did some research on that adjustable pcv and it does get good reviews. Seems interesting, I just wonder what type of real world difference it would make? For $129 I would hope it would be noticeable.
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Re: pcv filter location

Postby jim327monza » Tue Mar 07, 2017 6:39 pm

After some research it would seem that the bulk of the 1968 4 brl 327's ran a fram fv-181. Since my 327 will be basically a replica of this motor, I will use this as a starting point. This should allow me to get the motor in the car, break it in , tune the carb, get an accurate reading on the vacuum, and then swap out -pcv's and gauge the effect. The pcv inlet on a holly 4160 is located on the passenger rear, to get the shortest hose run possible I mounted the valve in the passenger rear valve cover, fresh air inlet from air cleaner to driver front valve cover. This is opposite of the factory set up on the 262 but should not cause any problem. I looked at the adjustable valves but though that the price was to high.
Thanks Jim H
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