The Stovebolt Site Forums The Shop Area Engine Shop Deve's PCV system (valve)

On Page 95 of Deve's rebuilding the inline 6 book, he shows the Standard Motor Products V-237 installed. However it appears that the two photos in the yellow box on this page show a different valve: the left-hand picture has one male connector but the right-hand photo has two male connectors. He must have done an additional modification that he didn't describe?? Anyone have any experience with this?

Thank you

DEVE web site explains his testing of several PCV valves to get desired vacuum or flow.

http://devestechnet.com/Home/PCVInstall

Get ready to buy oil by the barrel if you use that method of installing a PCV valve. It will suck up splashed oil from the crankcase and turn your stovebolt into a mosquito fogger in some cases. The factory original PCV system used a baffled standpipe about a foot tall in place of the road draft tube to prevent oil splash from getting into the PCV valve.
Jerry

NOS pictures of factory set-up (there are others in the set).
https://www.flickr.com/photos/advance-design_parts_co/8460085515/in/album-72157631868452754/
Factory picture 1949.
https://www.flickr.com/photos/advance-design_parts_co/8665388167/in/album-72157633290718528/

Thanks guys. Good info

There is no way to get definitive proof, but I would think that the factory setup was just as good as Deve's

I'm sure the engineering department at General Motors asks him for advice- - - - - -right?
Jerry

Thanks for staying cool, Jerry.

Was that larger/longer road draft tube used in all years (1948-1955st, and through the end of 235/261 years)?

[I looked it up - see info below]
47-53 trucks (standard cab, downdraft tube) were the same as the part/box shown by Brad - part# 3693661
1948 was different (first year for PVC, I think - might have been for updraft engines only on 1948)?

1954 and later were different - does anyone know why/how?
(Note: the engine changed to high pressure oil system in 1954).

However, looking through Brad's photos - a similar height/style tube is shown on later engines.
Thank you, again, Jerry

Here's an image of the passenger car installation drawing from Chevy, original date '55, updated twice in Feb '56. Looks pretty much the same as Brad's parts, with the possible exception of the air cleaner attachment, and maybe some other pieces. Same style as the earlier version, with a tall tube on the breather.

I agree with drdoug

The lines/plumbing are most likely the only/main differences between the car and "standard" (down-flow) truck units.

Jerry,
Could the sucked up oil cause any engine running issues? I did this to my truck and , despite it running pretty well, when I did my first oil change after a few hundred miles it was low on oil. Really low.
Could it cause hesitation? Rich/lean conditions? I’m interested to see what you figure.
Thanks.

Most likely, you're getting oil-fouled spark plugs that are causing the performance issues. Once the oil gets into the intake, it's got to go somewhere- - - -into the cylinders, maybe? The only thing in the way of all that oil splashing around in the crankcase (thrown off the crankshaft and rods) is a little piece of sheet metal under the draft tube hole. Chevy wouldn't have gone to all the trouble and expense to make and install that standpipe if it was not needed to control oil splash. Ditto for the road draft tube- - - - -it is placed at the top of a tall, baffled tube- - - - -I wonder why?
LOL!
Jerry

Seems to me the more logical spot to locate the PCV valve and grommet, would be where the road draft tube is tee’d into the standpipe.

Your description is a little unclear to me, Phil (sorry).

Is the PCV tube the "stand pipe" that you refer-to? Most likely?

Your description sounds right since the PCV fitting is higher above the "draft hole" in the block on the GM PCV "draft tubes" (compared to the "height" in a standard road-draft tube.

This was an attempt to avoid "oil-mist" from fouling the PCV, when that "mist" was drafted/filtered out from between the PCV and the lower block and the oil pan.

I see what you mean. I was plagiarizing from HotRod Lincoln. He referred to the vertical cylinder that is connected to the block as a “stand pipe”.

Looking at the picture, if you cut the downtube off in the area pointed out by the arrow, and adapt the PVC valve and grommet to the cut tube near the tee, you would eliminate any oil splash and still be able to hook up the PVC system.

I’m quite sure I have seen this done before, But I can’t remember where.

If that is Deve's illustration - he must plug that out-flow tube?

And, is it high enough above the block that oil slosh/mist will not get to the PCV valve?

The picture is my current road draft tube with no PCV installed. I used it only to illustrate where I would locate the PCV valve. I believe its high enough because that is where the down tube (out-flow) is pulling its vacuum from. It seem logically a better place then directly from the block due to the increased height and the baffles installed in the “stand pipe”.

If you have a welder, you could always add an extension to the bottom by utilizing the cut off out-flow pipe, essentially duplicating the factory setup.

Just my thoughts.

If you can't make it taller, increase the diameter: the droplets will fall out of the air stream when the velocity drops, and drain into the block when the engine is shut off.

I just pulled the trigger on a NOS crankcase ventilator on ebay, the exact one that is illustrated in drdoug’s post, part number and all! My road draft tube was a bit loose and I was afraid of losing it. After talking about the PVC, I took a quick look and there it was at a reasonable price.

The Standard Motor Products V-237 valve used in the last 387 orders I have sent out of these PCV systems uses 2 inches of mercury out of an available 18-20. Meaning, the amount of vacuum is so small that it is not possible no matter how worn the engine is for there to be any oil or 'oil mist' entering into the intake.To prevent this problem further, I use a 3/8" diameter tube because the bigger the diameter, (panic is correct), the less possibility of liquids getting involved. Also, placing the valve further away from the bottom of the engine (perhaps further up the tube) wouldn't make the suction any less. Lots of testing and research went into this project (now years ago) to make sure just the right valve was chosen for these particular engines. No fouling of spark plugs, no oil usage, no problems.

To answer your original question, the new style V-237 has two ports. The 3/8" one is used and the smaller one is capped off. The smaller one can be used for testing the vacuum if you so choose. I keep in close contact with most of my customers and there have been no negative comments from those who have actually purchased it. I give full refunds and no takers so far. I am glad you are enjoying the book! PCV, stock or my system is a good idea to reduce crankcase gasses. Its a good conversation to have.The road draft tube works on the Venturi Principle after the vehicle reaches about 30 mph. The rest of the time, crankcase gasses are forming and wreaking havoc. The 235/261 engines were the last to NOT have PCV, My name was in the topic, so I felt the need to set the record straight. Hope this helps!

Link on Amazon for the engine book: https://www.amazon.com/Chevrolet-Inline-6-Engine-1929-1962-Rebuild/dp/1613254881/ref=sr_1_1?
Link on Amazon for pre-orders of the full restoration book: https://www.amazon.com/How-Restore-Your-Chevy-Truck/dp/1613255020/ref=sr_1_6?

(I hope all my old friends here on the premier forum for all things Advance Design are doing well! :))

I appreciate all the help from all the people on this site! Thanks Deve. Thanks Jerry. I will pull my plugs to see if they are oily. I’m not an expert by any means and both of you make a lot of sense to someone who is still a very young apprentice! I remain on the fence on this one! 😃

The PCV upgrade is one of the best things you can do for the engine health.
Another version for the GMC where the draft tube is also the oil fill.
This on is modified by cutting and turning the tube orientation and the road draft is removed.

Here is another GMC configuration I have seen and using on my GMC motor installations.

Interesting! In this setup it appears that the PCV is drawing air from the valve cover and drawing filtered air thru the crankcase. I assume the canister on the side would be for a filter.

yes. You are correct. A pleated paper filter is used. This set up can be used on a Chevy as well. I usually see these on the military 270's and 302's but have seen them used on 228's etc - for the pre-war trucks and later.

This type of draft tube and filter set up can be found on Ebay. I believe there are a couple on there now.

Locating an elbow or making an elbow for the valve cover should not be too difficult. One of my 261's has a home-made elbow that was tacked to a small metal backing plate, that was then tacked to the underside off the valve cover. A rubber line was then routed to the intake, that was drilled and tapped for a fitting and PCV valve. It works although not the prettiest I have seen.

Seems to make sense.

original filters can be found easy enough with a little patience and perseverance.

The round track small block V8's we built with extremely loose piston skirt and bearing clearances to prevent the engines from tightening up during extended periods of full throttle operation had massive amounts of blowby, more than any normal type of crankcase ventilation setup could handle. That's just a normal byproduct of race engine building- - - - -"Go fast for a little while- - - -win a few races- - - -blow up into a bunch of pieces of expensive junk!" Repeat as necessary. Run out of money!

The breathers we fabricated were made of two pieces of exhaust pipe about a foot tall, welded to the driver's side valve cover, with vented oil fill caps attached to the top. Quite often, we would zip-tie a couple of folded up shop towels around the breathers for extra filtering. I found that cutting angled slots into the pipes and welding pieces of thin sheet metal into them made the vapors and oil splash negotiate a kind of maze before reaching the top, and kept more of the oil from finding its way all the way to the breathers on top of the pipes. Something similar could be done to a standpipe fabricated to fit the breather hole in a stovebolt block, with the PCV valve at the top of the pipe. A sealed oil filler cap could be added if desired.
Jerry

I was wondering, would a baffled PCV in the valve cover like most engines I've ever seen make more sense, with a baffled breather on top of the draft tube, or at the other end of the valve cover?
Or, with a filtered breather on the outlet of the draft tube.

It makes perfect sense.That is why newer engines were fitted with them eventually.
I brought his very point up when Deve proposed his current design years ago.
All you would need to do is use an early draft tube which came with a oil fill cap, put a filtered oil cap on it, and close the lower end of the draft tube. Then put PCV valve on the top of the valve cover.
These old engines are prone to blow by when brand new due to loose tolerances compared to modern engines. This results in contamination of unburned gasoline and water vapor into the crank case. A good portion of these contaminants end up migrating upward and and can be seen wafting out of the vents of the valve cover at idle after a long drive. It also is the white oily gunk seen on the inside of the valve cover.
Having the PCV valve at the top of a ventless valve cover would effectively remove those contaminating fumes.
Having the PCV valve at the draft tube clearly would not. In fact, these fumes will be sucked down through drain holes in the heads and end up in the oil before the draft tube PCV has a chance to sip the fumes out of the crankcase. (PCV systems have a significant amount of restriction in them, so there is not huge amount of air rushing through them. If they did, it would act like a giant vacuum leak.)

Carl
resident armchair expert of nothing, but wordy, nonetheless

Agreed. The amount of suction for the total engine is between 18 and 20 inches of mercury, but for those of us who think more along the lines of pounds per square inch that is between 8.84 psi and 9.82 psi. So, the V-237 pulls out crankcase gases at about 0.98 psi. I would argue that it doesn't matter which direction the suction goes... from the valve cover or from the road draft tube location. Either way, the oil can mix with existing crankcase gases on its journey through the engine since all internal parts are coated with oil. The idea is to create a negative pressure where a slightly positive one exists. With no PCV, you have gases coming out of the valve cover AND the road draft tube which represents positive pressure. By adding a valve and connecting it to the intake, you have slightly (depending on the valve you use) negative pressure which pulls away the gases. (But only if the system is sealed. Valve cover and side cover gaskets aren't leaky, road draft tube port is sealed, and the dipstick has a good seal to the dipstick tube). Since this is all happening every second the engine is running, it's very effective.

I would also remind those of us who were there during the initial discussion years ago that we were all looking for the least invasive way to do this for all vintage 216/235/261 engines. The entire "Keep it Stock!" crowd who many of you are a part of didn't want holes in the vintage valve cover, or in the air cleaner, or in the road draft tube. When Dave and I and a few others engineered the system after lots of feedback from here, it was keeping that solidly in mind. With "Deve's PCV System" (which in actuality was a group effort) the PCV system can be removed, the road draft tube inserted and no harm, no foul.

Since the gases that are present are created on the bottom end as they are on the top due to friction, heat, oil and environmental characteristics, (thus the term crankcase gases) we did the best we could with the design Chevy gave us in the least invasive way. By inserting a freeze plug and grommet at the road draft tube port, we are sealing that hole completely which is important in closing the system for best performance for the valve. With about 1psi of actual pull, there is no chance of oil getting sucked into the valve or any other adverse effects with the added bonus of not affecting vacuum windshield wipers or brake boosters. This system works very well. Is it perfect? I am not sure any PCV system is perfect since you are combatting a problem that was created before the fact. (crankcase gases exist first). I only wish there was an easier way with our vintage GMC (stock) engines to accomplish the same thing. But a little effort and you can get it done anyway! Great conversation!

Research and how to make this system yourself is here: http://devestechnet.com/Home/PCVInstall

Thanks Deve and everybody

What about this course of action (keep in mind I am totally a rank amateur) for a truck that is a Sunday driver and not a daily driver: Leave the old original draft tube in place and just change the oil more often?

Thanks

An additional course of action (in addition to your excellent and practical suggestion, WarEagle1): always end a trip driving your truck for at least 15 minutes at 25+ miles an hour (if possible).

That practice/action will remove all foulness (mostly moisture).
(side benefit: you will not need to change your oil/filter more often than the prescribed miles/time)

I have never needed a PVC set up in any of my small 47-55st 216/235/261 trucks (however, I did need one in my 2-ton 1954 COE).

Untold numbers of antique engines got along just fine with the road draft tube ventilating system. They also were lucky to run 50K miles between re-ring jobs due to abrasive wear from ingesting dirty, unfiltered air. One of the positive results of the Clean Air Act of 1968 (entirely unintended , BTW) was an approximate doubling of engine life from using filtered air to ventilate the crankcase, and also purging acid-producing blowby fumes at idle and low vehicle speeds. Do it right, and a PCV system is a definite plus. If you're willing to keep a close watch on the oil level, put the PCV in a location where it can suck up liquid oil, and keep your valve guides well-lubed in the process!
Jerry

Think your theory is flawed. 6-8 qts of oil will not warm to 180-200* in 15 minutes. More like 90-120 minutes if ever, especially if your running 160* t stat. Very little moisture is moving out of the oil when the oil temp is 160*.

Likely if the outside temperature is 50-80* the stovebolt might never boil off water or even fuel without assistance from PCV. The PCV system performance is still hampered by oil temperature. It’s also the reason most say don’t start your old car in storage unless your really going to run it for more than a hour or two.

Thats the whole issue here and why the road draft were so poor at venting the crankcase........it need temperature and speed ........those two are rare so performance is poor because of poor design.

Data points from other sources on oil temperature:

1.When my coolant temp hits 190F, my oil is usually right around 130F.

2.My brothers Corvette has an oil temperature gauge on the DIC. There is no relationship between oil temperature and coolant temperature in his car. The biggest factor on oil temperature is engine speed, again, at least in his car. Loping around in traffic, the oil doesn't really go over 130-140*F (similar to jigen's experience). But drive a steady speed down the road at 3,000 rpm, the oil temperature will begin to climb, and can reach 180*F or more. Slow the engine speed down, and the oil temperature will fall back down.

"Very little moisture is moving out of the oil when the oil temp is 160*."

I am not trying to "boil off water".
That would be a silly undertaking.
My engines are in good condition.

If I had a PCV system, I would be trying to draft-out any vapors that get into engine from wherever.
Where/when/how do you suppose that water gets into the engine (I know a few ways, but not after 1955st; and, not in my 1954 engines)?

What does a PCV system do?

Point taken on combustion gas being vented off. PCV excels at removing those combustion by-products and blow by gases.

“That practice/action will remove all foulness (mostly moisture).” This statement was my concern on moving moisture.

The moisture and fuel contamination in oil will still be a huge concern. As you mentioned that why the oil change interval in the ‘50s were 1000 miles or less.

Just ran my 228 up and down the highway at 50 mph for 30 minutes........possibly the last drive of the season.
Engine temperature 180*
Oil temperature bottom of pan 110*
Outside temp 35*

I recently (last week) changed my oil/filter (15W-40 detergent oil) after 2,500 miles.

No sludge/moisture.

Lots of 15-30 minute cruises (and, four 200+ mile trips) in those 5 years.

What's the best possible air/fuel mixture? 14.7:1 by weight, known as a "Stoichiometric" mixture. Its only byproducts are CO2 and water vapor, since the carbon atoms in the gas are all converted into CO2, and the hydrogen becomes H2O. Combine CO2 and water vapor in the crankcase from blowby, and you get carbonic acid. (Add a little sugar and caramel color and you get Coca-Cola). If that acidic vapor isn't purged by some type of crankcase vent system, it eats bearings.
Jerry

Thanks, Jerry

"If that acidic vapor isn't purged by some type of crankcase vent system, it eats bearings."

Will the road draft tube be inadequate, if you follow my suggestion: " . . . always end a trip driving your truck for at least 15 minutes at 25+ miles an hour (if possible).

It's better than nothing, but virtually none of our engines are run the way they were designed. Get it hot, drive it like you stole it, and repeat the same thing every day. Truck engines in particular were meant to be worked like a rented mule, and probably stayed in better overall condition than the Chevy sedan driven a few blocks back and forth to work every day by the local spinster librarian. That's assuming the truck got regular maintenance and oil changes. Stubbornly sticking to a 70 year old crankcase vent system when something better is available is sort of like bathing once a week in a steel washtub with water heated on a wood stove, using grandma's lye soap, instead of showering every day with more modern personal hygiene products!
Jerry