Another PCV question...

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Oct 5, 2006 | 12:20 AM

josh390

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Another PCV question...

First, let me thank ya'll for the help so far! I know the PCV valve is important, and I plan on replacing the worn out hose on it when I get my new heads and throw my 390 back together. My question is this: I have a chrome breather assembly... chrome valve covers, chrome oil filler cap. The PCV valve on the other valve cover is where it's supposed to be, but I don't have the hose that runs from the breather to the oil filler cap. It's just a chrome mushroom cap, no hole for the hose. How important is the hose going into the oil filler cap? Do I really need it along with the PCV, or will just the PCV be enough? It's an after-market breather assembly (obviously), so I'd have to rig a way to route a hose from it to a "proper" oil filler cap. This will detract from the "clean" look of the engine, which I'd like to avoid, but I also want the engine to run right when I get her put back together.

Thanks in advance

Oct 5, 2006 | 01:37 AM

Hypoid

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From: Golden, CO

Are there holes in the cap? That's pretty common to see. The vacuum through the PCV pulls the bad air out, but where does the good air come from before it goes through the crank case?

Set up a filtered source for air to enter the crankcase and you'll be good to go.

Oct 5, 2006 | 02:26 AM

josh390

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That's what I'm saying... I don't have the original breather, valve covers, or oil cap for this truck, so I'm not sure. I'm *assuming* that the original breather had a line going into the oil cap, but this one doesn't.

Ok... so another question. Do I need to get one of those breather caps, or does the air into the oil inlet *have* to come from the breather on the carb?

Oct 5, 2006 | 10:12 AM

Redmanbob

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Joined: Oct 2005

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From: Mddl A MexCans

On my 352 the passenger valve cover has a similar hole in the top at the rear with a rubber grommet, that the PCV valve inserts into. Then a hose is connected from that to the Phenolic plate under the carb or breather one ?.. I think, need to look at it..has been a while. The filler cap is at the front of the driver side and is only a filler cap with funnel kneck 2pcs... would seem easy enogh to just drill a hole for the grommet in the custom cover and hook it up.

Oct 5, 2006 | 10:13 AM

tomw

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From: suburban atlanta

As Hypo said, you need a filtered source of air for the crankcase ventilation system. If you can find a chromed (matching) filler cap with a built in filter, you'd be fine. If you can find filters that you could mount on one or both rocker covers, you'd be fine with that. I can't think of another place to feed air to the crankcase w/o lots of non-sheetmetal work.
It does not have to come from the air cleaner if you can filter it before feeding it into the crankcase.
tom

Oct 5, 2006 | 10:16 AM

krewat

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From: Long Island USA

How big is the oil filler cap? Is it just a cap or a breather?

If it's 2" or so high, turn it over and look at the bottom, and see if there are holes around the outer edge, and if there is any filter material in it. If it's just a flat cap, that's not good.

The stock setup is PCV in passenger side rear of valve cover, breather cap on front of driver's side cover.