Early Chrysler PCV valve from Plymouth Newsletter, 1948!

[MarcDeSoto]

I was surprised to learn that Plymouth offered an early Vacuumatic Crankcase Ventilator system as early as 1948.  It was invented during WWII for tank engines to be able to ford streams without flooding their engines with water.  In this 1948 version, it doesn't mention smog reduction, but for use in very dusty areas, and for diverting engine blow by so it doesn't form sludge in the crankcase.  

Edited February 19, 2023 by MarcDeSoto

[Doug&Deb]

That’s really cool. I wonder if any of those still exist. Goes to show how advanced Mopar engineering was.

[Sniper]

Very timely.  My son and I were discussing this very issue last weekend.  Showed him the difference between how the 2015 BMW does it and how my 51 does it.  Discussed how it was on military trucks and he guessed why.  Told him when I was a kid the road between the tire ruts were always blacker than any other part of the road due to oil, from road draft tubes. 

Edited February 19, 2023 by Sniper
and rope rear main seals, lol

[Bryan G]

You always got the "good things first" with Chrysler!

[Bob Riding]

What's the best way to add a PCV valve to our flatheads? I know Vintage Power Wagons sells a unit, but I seem to remember a thread or two on how to piece one together from readily available parts.

[wagoneer]

7 hours ago, Bob Riding said:

What's the best way to add a PCV valve to our flatheads? I know Vintage Power Wagons sells a unit, but I seem to remember a thread or two on how to piece one together from readily available parts.

 

 

[JBNeal]

additional information - partial PCV conversion

additional information - PCV conversion upgrade

[Loren]

A PCV system is a must ( even on race cars ).

The products of combustion are many but most notable is water vapor. When it mixes with Hydrochloric Acid ( another product of combustion ) it forms sludge.

Modern motor oil has additives to control the acid but the water is left up to the engine. Putting the crankcase under a small vacuum pulls the water out thus preventing the formation of sludge. When you remove the oil pan of an old engine you might find a grey sludge at the very bottom under the black sludge. This is lead from the fuel and blowby past the pistons. You won't be seeing that much anymore so check it out.

The government finally required car makers to install PCV systems in 1965. As you can see Chrysler was way ahead of the game. I can speculate as to why they didn't start putting them on all their cars in 1948 and the reason could be the General. Watch the movie "Tucker" and you will understand. If the General didn't invent it nobody else could use it, for as was said "What's good for General Motors is good for the U.S.A." And they certainly thought the opposite was true, "What is bad for General Motors has to be bad for the U.S.A."

When you look at the Chrysler system it was not primitive in any way.

There are some variations but they all work pretty much the same way even 85 years later.

[harmony]

11 hours ago, wagoneer said:

 

 

Good to know stuff.  The next time I see that tube coming off the bottom part of the oil bath air cleaning, I'll now know what it's all about.

 

[Bob Riding]

3 hours ago, Loren said:

A PCV system is a must ( even on race cars ).

The products of combustion are many but most notable is water vapor. When it mixes with Hydrochloric Acid ( another product of combustion ) it forms sludge.

Modern motor oil has additives to control the acid but the water is left up to the engine. Putting the crankcase under a small vacuum pulls the water out thus preventing the formation of sludge. When you remove the oil pan of an old engine you might find a grey sludge at the very bottom under the black sludge. This is lead from the fuel and blowby past the pistons. You won't be seeing that much anymore so check it out.

The government finally required car makers to install PCV systems in 1965. As you can see Chrysler was way ahead of the game. I can speculate as to why they didn't start putting them on all their cars in 1948 and the reason could be the General. Watch the movie "Tucker" and you will understand. If the General didn't invent it nobody else could use it, for as was said "What's good for General Motors is good for the U.S.A." And they certainly thought the opposite was true, "What is bad for General Motors has to be bad for the U.S.A."

When you look at the Chrysler system it was not primitive in any way.

There are some variations but they all work pretty much the same way even 85 years later.

I'm going to do it. What modern valve should I use, or should I go with VPW's system?

[Sniper]

You know, I wonder how well adding a PCV system would help with oil leaks?  I know the 318 I had in my 87 Diplomat would pull a slight vacuum in the crankcase at idle.  Witht eh road draft setup there is no vacuum if the car isn't moving and I am not sure how fast you need to move for it to start drawing?

[Loren]

California enacted a PCV mandate years ago ( again decades ago ).

My Dad had a 55 Ford Courier Sedan Delivery with lots of miles on it.

When they hooked up the now sealed crankcase and started the engine, it had enough blowby that pressure built up and pushed oil out the rear main seal.

I know for a fact that old 272 cid V8 was tired beyond any reasonable service but it started and that's all he cared about.

So will they help with oil leaks? It depends. lol On a new engine it will keep the oil clean and that means longer life, on an old worn out engine maybe not.

 

PCV valves have evolved a little. Most are just controlled vacuum leaks and some have a "one way" valve to prevent an intake backfire from doing any damage.

That's what rattles when you shake them. Carburetor cars should have the one way valve, fuel injected cars can get away with just an orifice.

 

Pep Boys used to sell a gizmo that plugged into the oil fill pipe that had a 3/4 inch flex pipe you pointed at the intake of your air cleaner. It didn't put vacuum on the crankcase but it did redirect the blowby to where it could be burnt.

There's no reason you couldn't fabricate your own PCV system using standard stuff you can get from one of the auto parts stores. Just know you will need to give the idle mixture and speed a tweak afterwards.

 

On a couple of engines I've seen two kinds of "Road Draft Tubes" One is just a bent tube with a hole for the mounting bolt. The other has a round end that goes into the block with a filter in it. I know I've seen that same round filter type with a fitting for the pipe to the PCV. Anyway if I made up one that's the part I'd start with. Put a generic PCV "anti-back fire one way valve" in it with a rubber grommet and a tube to the intake manifold. I like that filter idea a lot.

[DonaldSmith]

My PCV system, from 2009:

 

Instead of Draft tube, large pipe cap, tapped for 3.8" pipe:

 

 

Tubing, hose, FV 333DP or MG PCV333 valve, pipe fittings to manifold, with tee for vacuum gauge

 

 

Tubing, hose, tubing from air cleaner:  (Dry paper filter instead of oil)

 

XX

 

Tubing to oil filler tube.  (Air inlet in cap blocked off)

 

 

 

 

[Adam H P15 D30]

I wish I took a picture but what I did is cut the bottom 2/3 off the road draft tube, flipped it so it points up, put an off the shelf PCV rubber grommet in the tube and installed a common press in PCV valve.  Easy-peasy

[Adam H P15 D30]

Found a picture...