Just reposting this as some were having difficulty finding the old link,

Drilled and tapped to suit 1/4 NPT valve AC Part number CV726C

Apparently standard on a 1968 C*** Camaro

I have run a hose from here into the rear of the manfold vacuum fitting which is facing rearward straight out and down to the PCV.

Dutchy. Thanks for reposting. One of those tips that just gets better over time.

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Here’s the link for the original thread where you originally submitted the process of installing the PCV valve at the rear of the block as opposed to installing it in the valley pan or a valve cover.
Installation of PCV valve into the top of the block

The '64 Ford truck part has flow "checked " from the threaded end and throttled from the "hose" end.

The AC part has flow throttled from the threaded end and "checked" from the hose end.

The check valve prevents a backfire from blowing back into the valley.  

I'm going to give that one a try.

Dan

I saw one at my NAPA store (for a 283 BelAir) and found it is BLOCKED when you blow in the threaded end.  These valves have no arrow or other indicator as to direction of flow.  You have to test each one.

There are lots of pcv valves that can be used, including the "double hose ends" if you want to do your own modification.  Some have an ell at one end, which helps too.

If you have a carb spacer, you can tap the hole and screw a modern PCV into it (available everywhere for three bucks).

The one you bought can be used if you screw it into a 1" carburetor spacer.
You cannot screw it into your valley pan or block.

See previous posts.

The valve is installed so that under high vacuum conditions, ie idle, the pintle moves away from the full flow position to allow a small amount of air to flow.  At low vacuum conditions, ie cruise, the pintle moves to the full flow position for maximum scavenging.  At idle, if the valve were full open, it would be a huge vacuum leak.  A backfire would be the opposite of high vacuum, since it is pressure.  The pintle would move to full flow and would not restrict the backfire pressure from entering the crankcase.  If the system is workinig properly, there shouldn't be any explosive gases in the crankcase anyway.

I found an old pcv in my box of "stuff" this morning that works properly when threaded into the crankcase, ala Dutchy's installation.  It is an AC #CV590C.  Unfortunately I can't reference what size engine it came from.  Anyione have an AC catalog?

I didn't stutter when giving that advice.   Ford had Paxtons back in Y-Block days, but they separated intake from crankcase gasses.  If intake pressures EVER get higher than crankcase, that valve is not supposed to inject even the smallest amount of blended air/gas mixture into the crankcase.  In fact, if the PCV doesn't stop like a check valve, DON'T USE IT!

You may have missread your manuals, John.  Could you scan those sentences to share with us?  I think you are confused about when the PCV operates at idle speed (most vacuum) and 'most restricted' flow.  I'm sure the manuals are calling this condition a controlled orfice.  As the vacuum goes down under normal driving speed, the valve lets more crankcase air in.  At Wide Open Throttle (zero vacuum), the PCV is about useless.

Dave Dare

I have 3 Paxton blown '57 Fords.  Of course the intake is separated from the crankcase. There weren't pcv valves in '57.  All three of my cars are equipped with road draft tubes.

As for the manuals, I didn't mis read them.  Sorry, I can't scan, but I'll mail you copies if you need to see them.  Do you have access to any Ford manuals of that era?  Remember, except for Corvairs and Olds F-85s, there weren't turbocharged cars then.  Corvairs had draft tubes, I don't know about F85s.  My GM manual is Buick, no turbos in '65.  No turbo '68 Fords either.  That's why there wasn't a section in the manuals about pcvs and turbos.  I stand by my statement.  Thanks for your input.

Dave.  Here are the picture posting instructions in case you missed them in the past threads.

Generalized picture posting instructions

For those of us on dial up, your particular picture hosting site inhibits the threads in which you insert picture links from coming up in a speedy manner.  Thanks.

Two references I cited above are not year specific.  PCV valves haven't changed, either.  They vary in size and configuration (straight or ell, threaded or not), but they all work exactly the same way.

Retrofitting a new PCV to an old engine block is easy, but must be done properly.  If you had a good understanding of the operation of any generic PCV, you would not have made your false and dangerous statements.  Do your homework and never criticize correct safety information.  I only pray nobody gets hurt.

To my fellow Y-Block restorers and enthusiasts:
PCV's rarely get changed because they last so long under normal wear.  Some books ask you to rattle as an indication that it is still good.  That is NOT a good indication because the spring can be broken (and it will still rattle).  Also, make sure your PCV blocks in the backflow direction to prevent explosive gasses from entering your block.

Dave Dare
Ford Motor Co., Dearborn

I did not refuse to quote because I would be proven wrong.  I'll go ahead and quote, but you still have the option of telling me again that I can't read, or that I changed the wording.  Here goes, 1968 Ford/ Mercury manual, section 8-33, under the heading "CLOSED CRANKCASE VENTILATION SYSTEM": The first part of the explanation tells how the air gets into the crankcase and how it circulates within it.  Do you want that quoted too?  Then it continues:  "During idle, intake manifold vacuum is high.  The high vacuum overcomes the spring pressure and moves the valve to the low speed operation position (Fig. 10).  With the valve in this low-flow position he ventilating air passes between the valve (jiggle pin) and the outlet port.  In this position there is minimum ventilation but it never completely seals off the air flow.

     As engine speed increases and manifold vacuum decreases, the valve spring forces the valve to the full open position (Fig 10).  This increases the flow of ventilating air."  End of explanation.  Next words on the page are the heading for the next section, "EXHAUST EMISSION CONTROL SYSTEMS".  I would go ahead and quote the GM manual, but if I can read it correctly, it says essentially the same thing.  So does the Chilton.  I quoted the Ford manual for your benefit, Ford man that you are.

Now to my fellow Y Blockers on this site.  I apologize for extending this thread to this extent, and I will have nothing further to add.  Thank you for bearing with me.

When engine is at idle with high vacuum the jiggle pin moves toward the right when vacuum has overcome the spring and closes down the flow past the jiggle pin where marked "to intake manifold" on top picture, you will notice the spring is more collapsed in this condition and the rear of the jiggle pin is more open.

When engine is in high speed operation/low vacuum the jiggle pin is more toward the left with a greater opening on the "to intake manifold end", however the "from crankcase end" is more closed and restricting the flow caused by the spring. Notice the flat end on the jiggle pin by the dual arrow at the "from crankcase or rocker cover" end. Air flow does not pass through the jiggle pin. It passes around it as the jiggle pin is a solid piece with no through hole.

If in a backfire or blowback condition the jiggle pin will more toward the left (ie) pressure has come from "to the intake manifold" end forcing the jiggle pin towards the left and closing off the orifice hole to the "from crankcase or rocker cover" end by the flat end of the jiggle pin.

marv

any guy that can get his car out of a shed after winter put it on a truck & without raising the hood can pull 11sec runs on a drag strip knows what he's doing, i believe the original thread of dutchys was a simple re-post of his old thread which seems to have got highjacked .

btw dave as you have only been with us a short time the reason your specified thread from mr4sppedford didnt get told about picture posting is john may have broadband so he woudnt have trouble loading it & as ted hasnt said anything its possible being as busy as he is may not have seen that post yet & both are the moderators for the whole site as jim the owner cant keep an eye on everything while he works in the back ground so we can all benefit from y-blocks forever. thats all im going  to say.