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PCV question

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GMacLaren View Drop Down
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    Posted: May-29-2015 at 5:06pm

(Ford 302 V-8, circa 1974.)
Here’s a photo of the “spacer” between the carburetor and intake manifold.
It’s “upside down” showing the path it imposes on the crankcase fumes picked up
via a PCV valve in valve cover. The “spacer” piece is 1-1/8 inches in height.
I’d like to eliminate that 1-1/8 inch by routing fumes directly into the intake manifold.
There is already a threaded hole in the manifold, now plugged with a pipe plug, making it
a simple thing to unplug that hole, and route the fumes there, instead of into
this “spacer."
Your thoughts?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote GottaSki Quote  Post ReplyReply Direct Link To This Post Posted: May-29-2015 at 5:23pm
I prefer to distribute the vapors amongst all runners vs one, so to not create a lean condition in one jug and risk burning a piston.

That said, some route that way without incident.

Newer carbs have the pvc port right on them. If your carb is on the way out, its a simple solution.
"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 81nautique Quote  Post ReplyReply Direct Link To This Post Posted: May-29-2015 at 5:24pm
you can certainly do that George although there is concern about leaning out the cylinder/s on that intake runner. Not sure that it's been proven to be a problem or not though and several, myself included, have a PCV plumbed that way.

Can I ask why you are removing the spacer?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hollywood Quote  Post ReplyReply Direct Link To This Post Posted: May-29-2015 at 5:35pm
Because of the engine tilt, aren't the rear most cylinders fairly rich already? Given the choice you should plumb to back.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GMacLaren Quote  Post ReplyReply Direct Link To This Post Posted: May-29-2015 at 5:35pm
Originally posted by 81nautique 81nautique wrote:

Can I ask why you are removing the spacer?

I'm trying to make the engine box smaller -- narrower and lower. It's always seemed (to me) to be "too big" for the boat. The "spacer" is 1-1/8 inches high, and employs two thick (@ 1/8" each) gaskets instead of one.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GMacLaren Quote  Post ReplyReply Direct Link To This Post Posted: May-29-2015 at 5:55pm
If the "spacer" was phenolic, I thought it might be an insulator to help prevent carburetor boiling or heat soak. But being aluminum, I doubt if it helps much -- if at all. Could it be needed to improve vaporization? I'm not sure where the existing plugged hole enters the manifold circuit -- and would rather not remove manifold to see. If I do the plumbing, I'm quite sure it would be very tight fitting -- no risk of leak.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cboland Quote  Post ReplyReply Direct Link To This Post Posted: May-29-2015 at 6:33pm
I don't mean to threadjack here, but speaking of PCV valves, I've never paid much attention to mine. Is this a part that should be replaced periodically? I'm at 1100 hours on my engine and I know I haven't done anything and I doubt previous owners did.
Bud

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Post Options Post Options   Thanks (0) Thanks(0)   Quote GMacLaren Quote  Post ReplyReply Direct Link To This Post Posted: May-29-2015 at 6:42pm
Originally posted by cboland cboland wrote:

Is this a part that should be replaced periodically?   
It's my understanding that if you remove the valve, shake it, and hear it rattle, it's good.
There are some good descriptions of its care and function on the web.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GMacLaren Quote  Post ReplyReply Direct Link To This Post Posted: May-29-2015 at 6:49pm
On my boat, the "clean air" intake is via the filler cap.
And the blowby/oil vapor fumes are introduced via the spacer shown above.

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