The Stovebolt Site Forums The Shop Area The HiPo Shop 235 PCV valve

Hello all you fellow stovebolters; My question is, I just had my 235 motor rebuilt and want to install a pcv valve. My intentions are to remove the downdraft tube and install a freeze plug in the hole with a 90 degree pcv valve in this location and run the vacuum line to the intake manifold. I'm also installing a breather on the valve cover for fresh air. Is there any reason that this will not work? I remember seeing something concerning this in one of the posts, but can't find it now. Any suggestions? I appreciate all the input and advise...Thanks...Richard :hammering:

Hi Richard,

I have tried several combinations to add a PCV, all of which gave less than satisfactory results. On my recently installed rebuilt 235 I elected to stay with the road draft tube. I'm no purist but because it worked as designed.

My first attempt with my decent running (low blowby 235) was with the pcv valve plumbed into the top of the road draft tube which was plugged at the bottom. Ran a 3/8 OD hard line around and tied it into the side vacuum port on the intake. Used a vented cap which drew air from the air cleaner.

My second attempt was with a valve in the rear of the valve cover....added a baffle inside to cut down on splash. Used basically the same plumbing. Neither did the job....noted oil being forced from my front and rear seals.

I figured that the problem was the lack of volumn of vacuum through the 3/8" OD hard line and through the 1/8NPT port in the intake.

If you are trying to comply with your state's testing standards I would try a 3/8" ID line and open up the vacuum port on your intake to 3/8NPT. Won't offer any guarantee but I do think it will give you a better shot at scavenging your engine. Hope this helps.

Maybe some of the others will have a better idea. Think I have some pics in my album.

Dave

My 302 GMC has a good factory PCV setup. It has an oil breather/filler where the road draft tube would go and a valve that runs from the valve cover over to the intake manifold through a 3/8" hard line.

You need a good sized line from the valve to the intake. Put a tee where the vacuum line goes to the wipers and use that.

The factory setup on my '54 Chev. sedan had the pcv in the top of the former oil filler/road draft tube and a non vented oil filler cap in the valve cover. It worked just fine, no blow by and no oil leaks.

Hey chevman - are you sure that's factory? I don't remember ever seeing a pcv setup on a '54.

Bebop - welcome to the 'bolt!! I don't know what year your rig is but if it didn't have a pcv setup on it originally, why go there? The roaddraft tube does it's job just fine.

A PCV system was available in '54 on all truck engines, in all sizes of trucks. And, it was set-up as described by bebop40, except the oil filler had no breather and the valve cover had no slits in it (either would allow non-filtered air to enter the valve cover).

Passenger car options might have been different, but the 1508 Panel Delivery had a PCV option in 1954 (so, it would seem that other passenger cars had the a PCV option).

Hi Guys, thanks for your input; The only reason that I considered a pcv was because the shop that rebuilt the motor said that I needed to install one or it would leak oil, but most of the comments that I have received from the forum and others is that it's not needed so guess I'll just stick with the road draft tube. Thanks...Bebop40

Waldo, I bought it new from a Chevrolet dealer, so I guess it was factory.

Well, just shows to go ya', I learn something new almost everytime I'm on the Stovebolt Pages!

the TF trucks had a [primitive] PCV setup , prolly the same as the 54

Tim, that's "1508 Sedan Delivery"

Bill