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Air breather

Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=48087
Printed Date: March-28-2024 at 9:48pm


Topic: Air breather
Posted By: AlfaDon
Subject: Air breather
Date Posted: September-26-2019 at 9:19pm
I want to change the air breather that’s on the valve cover of my 351W. It it possible to rotate it to change the breather hose orientation?   Or, is it ok to remove it and use a breather that sits on top of the valve cover, one that you can pull out to fill the engine oil? Is it a problem to vent the blow by gases into the dog box instead of the hose that sits in front of the spark arrestor?

The current hose configuration blocks my view of the fuel pressure gauge

Thanks
Don



Replies:
Posted By: 8122pbrainard
Date Posted: September-26-2019 at 9:38pm
Don,
I feel it'd best to relocate the gauge rather than mess with blow by.

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54 Atom

/diaries/details.asp?ID=2179" rel="nofollow - 77 Tique

64 X55 Dunphy

Keep it original, Pete
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Posted By: KENO
Date Posted: September-26-2019 at 11:18pm
Originally posted by AlfaDon AlfaDon wrote:

I want to change the air breather that’s on the valve cover of my 351W. It it possible to rotate it to change the breather hose orientation?   Or, is it ok to remove it and use a breather that sits on top of the valve cover, one that you can pull out to fill the engine oil? Is it a problem to vent the blow by gases into the dog box instead of the hose that sits in front of the spark arrestor?

The current hose configuration blocks my view of the fuel pressure gauge

Thanks
Don


You must be talking about the oil fill pipe with the hose that goes from the side of the pipe over to the flame arrestor.

I don't see any problem with rotating it if you can or removing it and just putting a breather/fill cap in it's place .

If you look at a diagram of how the PCV system works, air goes into the engine through that tube or cap and ends up carrying blowby gases through the PCV valve back into the intake manifold

Depending on PCV valve condition, the amount of blowby, and engine vacuum, blowby gases can come out of the breather/fill cap instead of clean air going in.

If you google "PCV system" you'll find various explanations of how the system works

The automotive system draws air from inside the air filter to get clean air without dirt,sand etc flowing into the engine. The marine system on a PCM 351 draws air from outside the flame arrestor since you really don,t have to worry about dirty air

Another reason I figure it should work is one of my boats has the fill cap/breather setup with no hose running up to the outside of the flame arrestor along with the normal original PCV valve setup and there were no differences in how it runs as compared to the original setup.

I'm not sure on long term affects, it's only gone a few thousand or so hours this way

Why are you still looking at fuel pressure? I thought your new pump and overflow line hookup had it running good.

I never tried to rotate that tube, but I have an old valve cover with that tube and I can try to rotate it in the morning and see if it turns easily, breaks or just refuses to move.

I'll let ya' know


Posted By: KENO
Date Posted: September-27-2019 at 11:41am
Don

If what you have resembles what's in the picture, it will rotate. I had to delicately use a pipe wrench for some leverage but nothing broke or twisted.

And I even rotated it back to it's normal position again



Posted By: AlfaDon
Date Posted: September-27-2019 at 3:37pm
Thanks guys,
Pete, I understand you concern. That’s why I asked. I can put a 45* fitting behind the gauge and it should Move it out of the way enough to accomplish what I’m trying to do.

Keno, My filler looks just like yours. I tried rotating mine with a pair of channellocks and despite being cautious all I did was put a dent in the neck.   I finished modifying my spark arrestor to accommodate the vent hose. I’ll post a few pics to the other thread later tonight.


Posted By: KENO
Date Posted: September-27-2019 at 6:22pm
Originally posted by AlfaDon AlfaDon wrote:

Thanks guys,


Keno, My filler looks just like yours. I tried rotating mine with a pair of channellocks and despite being cautious all I did was put a dent in the neck.   I finished modifying my spark arrestor to accommodate the vent hose. I’ll post a few pics to the other thread later tonight.


You obviously need more practice at "delicate brutality"


Posted By: KENO
Date Posted: September-30-2019 at 7:32pm
Don

I stumbled into this picture of a 302 Ford in a Tique with just the breather cap and no hose up to the flame arrestor. like I mentioned earlier.

I just can't for the life of me remember who it belongs to, Pete might know   

Like I mentioned, I have an engine set up the same way



Posted By: Gary S
Date Posted: September-30-2019 at 9:43pm
I think they did that with alot of older engines



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http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS
95 Nautique Super Sport



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