The Stovebolt Site Forums The Shop Area Engine Shop 235 stand pipe pcv

All,
Quick question - in which part of this stand pipe is the actual PC valve? The fitting on the end (unattached in photo) is where I expected to see something of a ball or flapper that only allows air through in 1 direction. There is no such apparatus in this fitting. I can see through. As far as the stand pipe, it does appear that air only moves through in 1 direction.
So my question - is the fitting bad or exactly as it should be.
I cant date this stand pipe but it came out of a 235/261

For a future project to convert the draft tube to this setup, but only if it does what it is supposed to.

It has been so long since I modified mine I could be wrong. But I don't think it was obstructed in any it is the fact that it is a downdraft and the air over it at speed pulls the old air out and the vents in the valve cover let air back in to help scavage more air out.

I’m setting up the exact PCV on my ‘59 235 and the direction of flow should be from the crankcase to the intake manifold. The valve should operate in the direction of flow and close if flow reverses. Fresh air is from either the vented oil fill cap on the valve cover or a vent line from the air cleaner to the valve cover.

Phil, yes but where is the 1way valve? Is it integral to the pipe or is it a fitting attached to the pipe. Do you have a good picture of the fitting I question ?

Air should be able to flow through the standpipe freely in both directions. It's simply a baffled tube that prevents splashed oil from the crankcase from getting sucked into the intake by the manifold vacuum. The "valve" in your photo appears to be simply a calibrated vacuum leak, not a true PCV valve. It would draw a small constant air flow through the crankcase and into the intake, purging blowby and water vapor without severely affecting manifold vacuum. Later valves had a pulsating flow caused by a spring-loaded shuttle valve that reacted to intake pulses to take small sips of air from the crankcase. If that's the original equipment valve, just clean it thoroughly and reinstall it. It should work OK. I'd suggest giving the standpipe a vigorous cleaning with something like a strong solution of Trisodium Phosphate and hot water, followed by flushing with a pressure washer. The crud that comes out of a well-used standpipe or a road draft tube is pretty impressive! Back in the dark ages, we would fill one with gasoline, light it off, and let it burn for a while, and then shake the soot out of it.
Jerry

Here is a picture of the disassembled PCV valve that they used on the optional PCV system. It's part # 1544935 in the picture Phak1 posted.

Well there it is. I found that part number. Mine appears to be one piece. Maybe the guts were pressed in? But the valve piece does spring in and out. Thanks for the inputs.

I think you will find that it will come apart if you want it to. However, it's pretty simple; a solvent bath is probably good enough to clean it.

OK- - - -if the inner section is spring loaded, the orfice in the middle sets the minimum flow rate. Higher manifold vacuum causes the entire plunger to move, allowing more flow under high vacuum conditions. That's how all PCV valves work, even the Mickey Mouse disposable ones we have today. That one was designed to be serviced periodically, and last the life of the engine or longer.
Jerry

While my 261 was being rebuilt, I did a thorough cleaning as Jerry suggested on the standpipe and vent line that runs over the top of the valve cover. It was amazing the amount of crap that came out of both. Several cleanings with TSP/hot water and then a pressure washer and pressurized air for drying off got them squeaky clean.

Cleaning is on the project list this weekend.