Stovebolt.com Forums The Shop Area The Engine Shop NOS GM PCV Valve

I’ve been wanting to install a PCV system on my ‘59 235 for several years now. Couple of years back, I purchased a NOS PCV riser to replace the down draft tube. I need the PCV valve that screws into that riser and is listed as GM part #1544935. I can’t find a cross reference to that number. I did a search on PCV system on this site but seem to go down a rabbit hole.

I found a valve that physically would work on ebay, but want to confirm it will work before I spend 35 dollars on something that may or may not work.

Here is a link to the valve I’m looking at. https://www.ebay.com/itm/1447013202...r=&widget_ver=artemis&media=COPY

That looks like it. I don't know why you didn't find the info on this site. e.g.

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/942997/1.html

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1422635/235-stand-pipe-pcv.html

Gord, I found both of those threads, in fact I posted info to one, but I can’t find the cross reference to the GM part #1144935.

I do agree that the eBay item I posted does look correct, but was hoping for a direct cross reference or somebody that actually installed one to say “you need this AC part number…” and it works! Thanks for your suggestions!

Hopefully I’ll get some more input!

Phil,

Take a look at this previous thread on the subject.

Member "bouymaker" provided some detailed original and replacement GM part numbers along with the corresponding "AC Catalog" information in his reply post.

I just did a quick check on eBay and saw several NOS GM# 5647228 items being offered for sale.

Hope this helps out.

Dan

Perfect! That is the confirmation I was hoping for. I went ahead and ordered it.

Thanks Dan and Gord for your help!

GM parts wiki says that 1544935 was replaced by 5647228.

That's what the eBay listing says the part for sale is.

Best if it looks like & fits like the original, but that does not determine how it works.
There are only 3 important data points:
1. high vacuum orifice (cruising, light throttle)
2. low vacuum orifice (big throttle opening)
3. internal spring which sees engine vacuum and moves the internal restrictor cone to select 1. or 2.

If the engine is stock, a PCV from a very similar engine (size, power, tune) may work well.
If the engine has a big cam, the stock PCV will not work as intended.

I purchased a PCV valve sold as P/N 5647228, CV-469C a while back. It came in a silver and orange foil package. The valve was black with PAT. 32633699 stamped on it. Both ends were a correct fit, the air flow direction is correct and it has a similar spring-loaded plunger as the original AC 1544935 valve I have. The main difference is the 1544935 has a hole through the center of the cone shaped spring-loaded plunger. Air will moves in both directions; the volume of air will be varied by the movement of the cone. Perhaps PCV technology improved the design of the replacement valve.

Does anyone know what kinds of threads the 5647228 has? Looks like maybe pipe thread on one end and flare on the other?

It’s 1/4” NPT pipe on the end that screws into the PCV riser (I have the riser) and the other I suspect an inverted flare fitting.

I believe the original steel tube from the PCV to the Intake manifold was 7/16" outside diameter. The threads on both male fitting nuts were 7/16 NF. That size tubing was not easily available to me at the time. I replaced the tubing with 3/8-inch OD having male fittings with 3/8 threads, cut off one fitting, bent the tubing to match the original shape and changed to an appropriate brass fitting in the intake manifold. For the end into the PCV valve I purchased a 90-degree hydraulic hose fitting with a 7/16 NF (-7) male inverted flare on one end and a 3/8-inch barbed hose fitting on the other. The hose fitting had a metal shield over the barbed tube that was cut off. I used a lathe but it could be cut off other ways. Then used a small fuel/oil tolerant hose to connect the pieces.

I recently abandoned the PCV system on my '62 261. It caused an erratic idle speed at all times and did not get along well with the large vacuum leak as the engine evacuated the vacuum tank for the hydrovac brakes, etc. I couldn't get the idle speed below 900 RPM and then it would surge especially when hot. I had carefully dismantled and cleaned the valve according to the 1962 drawings.

Aside from that there was evidence of oil being sucked into the manifold from it. We'll see if oil consumption drops with the re-installation of the road draft tube. I looked for a new valve but couldn't find one by the part number stamped on the valve. Perhaps the superceded number would work but I'll see how the road-draft tube works out before I go hunting.

The original PCV system from a 261 big truck currently installed on the 235 in my 1954 1300 Chevy is working very well. No oil being sucked into the intake, smooth idle and seems to have reduced oil leaking from seals. There is also less “engine smell” in the cab. Very happy with the installation. The 261 in my other truck will use the same system.

The pictures in my previous post does not show the completed installation. Changes include a rubber hose connecting the top of the oil bath air cleaner (filtered air) down to the side of the valve cover and the installation of a non vented oil cap on the valve cover. This allows clean air to flow into the crankcase and the vapors from the operation of the engine to be drawn into the intake manifold through the PCV valve.

I received my NOS PVC valve (AC-469) today. The threads on the inlet side are 1/4” male NPT and the outlet is 11/16”-18 female inverted flare. Thus the reason for this post.

I pictured buying a few adaptors and installing CuNi tubing to make the connection. Well that seems to be much easier said than done, as “No1300” found out, and I am finding out. An 11/16”-18 inverted flare is for 7/16” tubing. Difficult but not impossible to find but I don’t have a flaring tool for that size and I’m having difficulties locating an adaptor for this size tubing. Additionally, on the intake manifold I have a 1/4” pipe tee that I want to adapt the tubing to. So I would need a 1/4” male pipe to 7/16” tubing inverted flare adaptor which seems impossible to find.

Thinking that using 3/8” tubing would be much easier to find the adaptor fittings needed, I started searching for the adaptors. That is also proving to be difficult. I can find a 1/4” male pipe to 3/8 tubing but finding a 11/16”-18 inverted flare to 3/8” tube fitting or even a adaptor to go from 7/16” to 3/8” has produced no results.

My next thought for a possible solution would be to find a power steering fitting (11/16”-18 inverted flare) to AN connector, cut off the AN side and tap it for 1/4” female NPT. Then I can buy 1/4” male pipe to 3/8” tube (5/8”-18 inverted flare) fittings.

And of course I could try to find an original setup.

I really would like to keep it hard piped, so if any of you ‘bolters care to brainstorm, I’d appreciate your input.

Just brainstorming….

One of the PCV setups for a mid 60s 283 v8 is pipe thread on one end and a barb on the other. Could you adapt that to the manifold end, use a very short section of rubber to a length of Nicopp in a size of your choice, and then hardline all the way to the PCV riser?

Wouldn’t be totally stock appearing, but the short section of rubber would be in a pretty hard to spot.

The information I supplied on the thread size for the 7/16“ outside diameter tubing was incorrect as Phak1 pointed out. The -7 fitting does have 11/16-18 threads. If you are willing to use 3/8”od tubing you could purchase the fitting shown in the earlier post and cut off the tubing just after the 90-degree bend and weld the 3/8 tubing to it.

I was unable to find a fitting to match the 11/16-18 fitting on the original pipe so I cut the fitting off and welded a piece of 3/8 fuel line tubing with the flared nut attached. The brass fittings to connect to the manifold were not hard to find. The 3/8” tubing slid nicely inside the 7/16” tubing and was an easy weld. If you look closely at the driver's side picture in the earlier post you can see the reduced tubing size and smaller fitting near the intake manifold.

As I mentioned above, I have abandoned the factory PCV setup in favor of the road-draft tube. Yesterday I returned from a 500mi road trip with camper loaded. That's ~9,000 lbs gross. Oil consumption was nil, weather was 80ish F, oil temp about 210, water temp 180-200F. No odors and no apparent oil underneath from the breather.

Despite the success of the road-draft tube, I'd rather have the PCV working. Perhaps I can clean the oil/vapor separator can as I did with the road-draft tube a while back. But I still have to come up with a new PCV valve. The one I have has the part no. Phak1 showed in his post. It is apparently worn out. I have all the necessary fittings and hard line.

That PCV valve will come apart so you can inspect it.

I did that and cleaned it. The pintelle shows a wear mark and once assembled it doesn't function well. So I'll look for a new one before proceeding.

So I ended up buying a 13/16” inverted flare to 6AN fitting and turning off the 6AN side. I drilled and taped that side out for 1/4” female NPT. I ended up shortening a 1/4” pipe tap to get more and deeper threads due to the short 13/26” inverted flare adaptor. I Also bought two 1/4” male NPT to 3/8” inverted flare adaptors and a 4’ length of 3/8” CuNi tubing with pre flared ends.

The 13/16” inverted flare screws directly into the PCV valve, the 1/4” to 3/8” tubing adaptor screws into the fitting I altered then the tubing attaches to that. The manifold end has an existing female 1/4” NPT Tee that screws into the manifold, so the other end of the tubing and adaptor will go there. Unfortunately, My tubing bender only goes to 5/16”, so I need to buy another larger one. My “not so” local HF was out of stock, so I am stalled waiting until I can buy one. Hopefully tomorrow then I can Install my new system.

In the meantime, I assembled the fittings and PCV valve, cleaned up the assembly then painted it with my favorite rattle can satin black.

I installed the PCV system today and all of the pieces I collected fit together well. I don’t like all the extra fittings but the system is operating and seems like its working well. I tweaked the idle screw on the carb, but I don’t really think it needed it. Took it for a test run and it ran great.

I think I’ll keep my eye out for the original tubing and manifold that attaches to the intake but in the meantime it’s installed.

Phil,

Looks like a really nice job IMO. Not sure there is lot you can do to change the manifold fitting setup without some serious parts hunting.

Thanks for showing the finished work.

Dan

Did your route the vac linehigh enough to allow removal of the valve cover without having to disconnect the line?

I thought about that when I was planning out the job and figured that it would be easy enough to remove two flare nuts to get it out of the way. I looked at the original routing and it didn’t appear to be that high over the cover.

The drawing looks like its actually resting on the valve cover. I wouldn't think that was correct, though.

I have the factory setup and I remove the tube before removing the valve cover. Running the engine with the valve cover off requires replacing the tube or plugging the vacuum port under the carb. The tube does not rest on the valve cover.