Got the Blues? Draft Tube to PCV Valve Conversion

Been wondering for a while about an issue that engines from our vintage vehicles tend to have... blow-by gasses coming out the breather cap and draft tube, generally looking gross and polluting the air at every stoplight and sign. Made it so I didn't even want to look at pretty girls as I pulled up alongside, in case they noticed the fumes making my van look like something out of a Cheech and Chong movie!

With the help of the users on the FordSix forum, I also learned that the accumulation of these fumes in the engine contribute to the build-up of sludge. The introduction of the PCV system to the engine allows these blow-by gasses to be reintroduced to the intake charge, and effectively evacuate the fumes from the crankcase. The intent is that the engine stays cleaner and the engine more completely burns it's fuel. The use of manifold vacuum is much more effective at getting rid of the fumes (that otherwise escape the engine) than the atmospheric vacuum created when air passes by the end of the draft tube while in motion. With their advice, I was successful in performing this conversion and virtually eliminating the need for me to hide my face when I stop at a light!

This conversion was on the van's 65 Ford 240 Big Six. I plan to upgrade my 62 Ford 170 Small Six in the same manner. Only difference is the draft tube location... front of block rather than back of valve cover... there is a way though!!! Hope this helps any of you that may be curious about this.



Removing the draft tube:



Removing draft tube hose bung, installing PCV valve and grommet.







PCV gasses enter the intake charge below the carburetor so gases do not gum up the carb. Removing manifold "plug" (coolant temp sensor?!?!?) and adding a bung. I've since wrapped these threads in teflon tape... just brass elbows the parts guy helped me size up.







Complete PCV system (includes original breather cap).



That's what I've been up to this week, in an effort to get my vehicle driveable again. I did notice initially that my carb neeeded tuning badly. The mixture screw was turned way out, which contributed to more visible fumes. If you perform this upgrade, expect that you will have to doublecheck your carb settings, though they should not change dramatically... the net result of the PCV system to the intake charge is like introducing a controlled vacuum leak.

On my conversion, I completed the job about 1am, as I was rushing to have my van available to some activity the next day. In my overtired stupor though, I reconnected the throttle cable wrong and it was binding. The next morning, after reattaching the throttle cable, the van is good to go!!!

Seems to me that would be a big old vacuum leak if you have an oil cap that is also a breather. If you could seal up the system I bet that really does reduce smoke, well done!

My guess would be that when the PCV signal is strong enough to open and draw fumes from the crank case, it would then breathe through the cap... it really isn't any different than a new vehicle that has the large hose running from the valve cover to the filter mounted on the inside wall of the air cleaner... I did read that it is in fact a "vacuum leak", but it's "controlled". To compensate, I think you would open your idle mixture screw just a little to accommodate the air and fumes coming from the PCV.

The difference is night and day with my engine. I recently got compression readings... two cylinders around 80 psi, two around 115 psi, two around 130 psi... tons of sludge was built up and blow-by was obvious. Now when idling at a light, there are no fumes at all. I assume that sludge is no longer accumulating either.

ChevyVanMan1 wrote:Seems to me that would be a big old vacuum leak if you have an oil cap that is also a breather. If you could seal up the system I bet that really does reduce smoke, well done!

The PCV valve is a metered (small oriface) vacuum leak. They are designed for the size of the engine, that's why there are so many different ones. If you put a sealed cap on in place of the breather, it can pull air and dirt in through the seals. The normal mid-sixties through 80s PCV is a type 4. This has a PCV as shown and the inlet side is connected to the air cleaner instead of the breather cap. The vapors are vented into the air cleaner (usually with a filter) during periods of low vacuum (full throttle) rather than the engine bay, further cleaning the air. Hs current one is a type 3 (vented to atmosphere).

You will find that if you change the oil less often that the carb adjustment will be off with fresh oil, that's how much vapor develops in the crankcase over time.

Side note; Honda found while running a Formula One car that they increased HP if the crankcase was under a vacuum. They had to design special seals and a pump that pulled 27 inches of vacuum. Absolute vacuum is ~30 inches!

sasktrini wrote:
The difference is night and day with my engine. I recently got compression readings... two cylinders around 80 psi, two around 115 psi, two around 130 psi... tons of sludge was built up and blow-by was obvious. Now when idling at a light, there are no fumes at all. I assume that sludge is no longer accumulating either.

With readings like that, it's worn. However, if you plan on rebuilding it, you can run a 1/2 quart of ATF in the motor for a few minutes before you change the oil. It has a lot of detergent in it, so it tends to clean the interior of the engine. I would not drive it or put a load on the engine with this however. Just run it long enough to get it up to temp and then drain. Do this a few times and the difference is noticeable. The only concern would be if it's really sludged up. You could break big chunks loose and plug the oil pickup. That will starve the engine for oil and cause a rebuild that costs much more!

Back when I got the van, I dug into the engine to deal with lifter noise, and de-sludged all I could see. I'm no longer worried about the chunks of sludge. And I've since swapped on another oil pump in case it was the cause of my poor top-end oiling. Have done the Rislone treatments and engine flushes... that part's all good for now. But I definitely have to make rebuilding my other 240 a priority! Actually think I'll be getting the short block started in earnest next week... that's another topic.

Bottom line is that my current engine was filthy using the draft-tube configuration, and I am convinced that the PCV system would have done a world of good on this engine. My results today are night and day.

sasktrini wrote:Bottom line is that my current engine was filthy using the draft-tube configuration, and I am convinced that the PCV system would have done a world of good on this engine. My results today are night and day.

YES!!! There was a lot of anomosity toward 'smog equipment' when it started out, and there were a lot of steps back for years. However, a PCV is a great improvement in all respects over a road draft tube. I laugh at people that modify their engines for more power and remove a PCV. Even drag racers use a crankcase evacuation system for a cleaner engine and more power. It won't work on a street car though.

Wow, this is a great mod. I definitely plan on doing this to my van. A few questions.. (I know this is an old thread, sorry!) Do you remember what the pcv valve you used was out of? Also, I am a bit confused, did you keep the original breather cap, or replace it with a sealed one? Thanks!

Soap, I'd suggest looking at the parts for a later model van with the same or similar engine for all the correct parts.
The best way to go is to have a 'closed' or type IV system.
This has a PCV valve in the valve cover, connected to a vacuum hose that connects to the base of the carb or an adapter. The hose is usually 3/8".

See the back of the valve cover? NOTE this is an open breather

Then you want a breather cap with a hose fitting that attaches to the air cleaner. There is usually a filter in the cap (looks like steel wool) and a filter on the side of the air cleaner where the vent hose attaches (but not always).

This has just the hose to the snorkle of the air cleaner



This prevents vapors from venting into the doghose. They vent into the air cleaner when vacuum is low (WOT operation or engine off) and are pulled into the intake manifold when vacuum is high (engine running, except WOT).

*WOT=wide open throttle

Thanks for the info Rod! This will be a very big help.. One more question.. Do you guys keep the oil bath? I was thinking I could fit a round paper filter in there and get rid of the oil. Any suggestions as to which is better or if it will even work?

since you are going to try to find a later air cleaner with the hose fitting, grab one that is a normal paper element housing anyway....

the only concern i would see with coreys set up is if the valve cover did not have a baffle where the pcv now lives, if the top end oiling is real strong oil could be pulled up through the pcv, i doubt it would happen but i guess it could.
ford also had a valve cover breather with the pcv in it, i think it was on some 300's but im not sure.

Wow... I haven't been around for a long time... wasn't feeling well and weather has sucked for the last year! Yes, valve cover has a baffle. Still use a breather cap, which I think is no problem because of the baffle... I like the look of them too. Still have the oil bath air cleaner. PCV routed to the intake manifold.

Parked the van not long after as snow flew! C'mon , SPRING!

Nice to see you back sasktrini

SoapDude wrote:Thanks for the info Rod! This will be a very big help.. One more question.. Do you guys keep the oil bath? I was thinking I could fit a round paper filter in there and get rid of the oil. Any suggestions as to which is better or if it will even work?

Hey Dude, I have an oil bath air cleaner assembly with a paper filter inside of it! I gutted all of the oil bath innards and installed a Wix #42055 paper filter. Simple to do, just takes a little time.

Saw this and started doing some research on doing this on my 144. I found this thread about it which should also help with your 170 when you get to it. I'm going to do this soon.

Great post! I"ve had my 170 E100 for about 5 months now and while some think the smell gives it the Old time "character", but those if us from this century don't . My wife loves the uniquness of the ride (it is older than she is) but I have to 1) Get rid of the smell, and 2) install seat belts before she'll ride with me again.

As I see it, I just connect the bottom of the venting tube that goes down the front left of the engine back up to the npt port in the manifold under the carb with a rubber hose? The pictures (in this post above) of the brass fittings at the carb are great. Exactly where and how is the appropriate Pcv "teed" into it? Would it Hang it upside down @ the bottom of the vent tube? (Does it matter if the actual pcv valve is right side up or upside down?) Then I just get a new air filter housing with a tube connection and connect it to a breather cap with a hose??? Would anyone have a part number or detailed spec that would identify a specific pcv that would be appropriate.

Does not sound too complicated, I guess it is just a physical mod, I mean the there is no "computer" to connect sensing wires too?

Hey Oldskoolvanin
I see you are from Jersey..good to have you on VintageVans.
I know your dilemma...ie about the fumes and the wife not wanting to ride in the truck. Three point seat belts are relatively easy to install...get the good ones. There is a post on VV,s about an install. As to the pvc install on your 144 I'd say try searching the junkyards for a complete setup (valve cover, pvc and air cleaner, etc)from an old Falcon or Comet. This way you have the year and all pieces match up. Corey aka Saktrini and/or Rod I'm sure will respond to your question if you IM them.About the fumes...never ending battle.....I'm running a 300 with a closed system and the doghouse still lets in fumes..no matter how many times I,ve sealed the rubber. My last straw attempt will be to put a small blower fan inside the doghouse soon. Anyway, welcome to Vintage Vans...I'll let you know when I'm going to the junkyard in south jersey that has a few earlies left.
Jim

Something to note:

The Big Six has the PCV and breather both in the valve cover, and it is split so that the breather allows fresh air in to the first half of the valve cover. Airflow is forced into the crankcase because of the baffle, and then is drawn up from there into the PCV half of the valve cover and into the intake charge.

With the Falcon Six, there is no baffle in the valve cover. I suppose that fresh air is introduced from the breather cap to the valve cover into the crankcase and directly out the draft tube.

I guess what I am suggesting for the Falcon Six, there's a couple options:
1) replace engine block draft tube with PCV
2) block original draft tube, create second zone by putting a baffle in the valve cover (must fit around rocker assembly), and put PCV valve in valve cover like I did on the 240.

On another thought, this doesn't eliminate fumes coming in through the doghouse leaks. What I observed was that sitting at idle made the fumes from the engine fill up the cab almost immediately, because the vehicle must be in motion for the draft tube system to work. Most were evacuating from the breather cap. So rather than dealing with a leaky doghouse, this solution addresses this one problem at the source. I think initially, I was looking to see if it was an exhaust leak.

I don't recall which PCV valve I used...