The Stovebolt Site Forums The Parking Lot Big Bolts 1955 chevy 261c.i. PCV valve

My engine came with the steel pcv valve chevy #5647228. The spring was broken so I tossed it and was planning on converting to a new pcv system but I found a new old stock valve. My question is how well that original valve works. Is anybody running a 235-261 with the steel pcv valve? My valve cover doesn't have the ventilation slits but has a tube fitting going to the air cleaner for fresh air intake

There nothing more that a one way check valve. As long as you can blow air in one direction and not the other, I would consider them good. If the part number is correct, your good to go.

1929-57 Chevy Master Parts List
Section 1.745
49-57 ALL 6 cyl VALVE, crankcase ventilator 1544935

1961 Chevy Parts and Accessories Catalog
1544935 USE 5647228

1971 Chevy P&A
49-61 All (6 cyl.),
5647228

Originally the crankcase ventilator was intended for military use but was also sold as an option to use on cars and trucks (RPO 217) for use in a dusty environment.
Beginning 1964 to 66, California adopted a PCV requirement for new and a retrofit to most 1950's cars and trucks.
Later on the EPA required all new cars and trucks to have PCVs.

The valves are ENGINE SPECIFIC and I would use what Chevrolet listed.
The AC catalog says the CV469 (GM 5647228) is a "replacement" valve for "heavy duty" usage.
Like the original OEM Chevy valve, it is made to fit the road draft tube with the threaded hole.

AC also lists CV208 or CV609 and CV695 for retrofit. Some have hose connections. Some screw into an adapter on the intake manifold.
I haven't looked into an alternative valve but if you search this forum you can find a lot of PCV information.
I prefer the original RPO 217 look but some prefer to hide the metal lines or rubber hoses.
It's all a matter of taste.

Does the steel PCV valve work? Definitely! It's currently on my 55 1st with a 261 that came out of a 6400.
You can take the valve apart for cleaning which is something you can't with the new valves.
Is a PCV beneficial? Yes. For the health of the engine.
The thing that makes the valve fail is an oil-burning engine where blow-by sludges the valve till it can't operate.
It that case any PCV is useless.

Here is a picture of the part the fits into the crankcase that the PCV valve screws into.

Phak1, yes, that is the standpipe I have but you're incorrect about the valve. This PCV valve is not a simple check valve, it has a movable venturi with a small hole in the center that is connected to a spring inside. Under high vacuum the venturi is pulled open by vacuum allowing a larger amount of air to flow around the venturi. Under low vacuum the spring pushes the venturi to the closed position only allowing air to pass through the small hole in the center. At least that's my understanding of how it works. Actually I think I have that backwards. The valve closes at high vaccine and closes at low vacuum.
Bouymaker, thanks for the info. I'm running a 1954 261c.i. bored .040 over. The original PCV threaded into the top of tube that replaced the road draft tube with a steel line to the intake manifold. I'm not sure what would make the PCV that I'm looking at "heavy duty" but I'm going to run it.

Your right, but I was trying to simplify it‘s operation, not knowing your degree of knowledge on the subject. The amount of air flow, at all different engine speeds and loads is critical to proper operation.

The PCV valve will also protect the engine in case of a backfire, which will force the PCV valve closed, so that the backfire flame can't reach the crankcase.

Here is a very simple illustration of a PCV valve that explains it’s operation.

The "Heavy Duty" was probably the term used for application on big trucks back in the early 50's (also WW2) not that the valve itself is heavy duty. Big trucks were the ones that usually eat a lot of dust and sand like during construction. Also the military working in the desert or fording a river. The valve was called crankcase ventilation. Fast forward in time, the California law required PCV (Positive Crankcase Ventilation) because of the severe smog in that state. The idea was to have an engine that is sealed-up. No leaking rocker arm cover(s) and lifter galley side cover to let engine vapors escape. Clean air in through air cleaner and combustion vapors and gases go out to the intake. AC made checkers (CT-1, CT-2 and CT-3) that tested the effectiveness of the sealed system. Hot Rod (Jerry) is familiar with this and installed a few of these retro kits in his day. Then comes the Federal (EPA) requirement for all cars and trucks in the USA.

I also have the metal tube from the road draft (actually crankcase tube, no drafting) to the intake adapter. Metal elbow with sealing pad on the valve cover and air cleaner. 5/8" hose between the elbows. It's important to have the correct diameter hose and metal tube for the flow through the CV 469.

phak1 It's metered