The Ford Barn

moefuzz · 09-16-2016, 12:50 PM

.

No need to spend $50 bucks on someone's wizzy "PCV" kit,
For around $5, you can install a PCV system on your Flathead..

There are many benefits in replacing the road draft tube with a proper Positive Crankcase Ventilation system on your Late model Flathead V8.

A): it helps eliminate the embarrassing smelly/hot fog that wafts out from under your hood at the stop light.

B): It helps to create a consistent vacuum inside the crankcase and oil galleys.
An actual vacuum/draw inside of your crankcase will aide in keeping the oil and oily residues from being pushed out from every available seal, gasket or open "hole" that is and/or resides in what we think of as an automobile engine.

C): A PCV system will help eliminate moisture that can and will accumulate in your engine oil and hence your oil pan, engine and intake galleys. Moisture is a major cause of internal engine sludge that builds up (over time) and generally coats all manor of things like intake valves, stems, springs and lifters.

D): When you think about it, The road draft tube is actually just a huge open leak unto an engine. While a great idea when it was designed, it was obsolete when the idea of a closed or semi closed System with a proper PCV valve was invented.

E): Eliminating the road draft "hole" and replacing with a proper PCV sets you on the path of creating an enclosed (as opposed to wide open hole) oil galley and crankcase. which brings us to;

F): Eliminating the open hole of the road draft tube shuts out the probability that the filler cap/breather will suck in air/dirt/moisture and debris as you drive along..
At throttle and while working the engine, your engine creates Pressure and this pressure will be pushed out the road draft tube (not to mention and/all gaskets/seals and other non sealed surfaces) and along with the pressure comes hot fog/moisture and oily residues..
Which directly relates to;

G): oily/grime. As you drive/work the engine, the inherent pressure of the working engine escapes from every available seal/gasket etc. and carries with it oily residue that coats your clean engine, engine compartment, firewall, chassis eventually swirling around and being carried away at and around your rear bumper...
...At working pressure, Everything accumulates an oily coating, even the guys headlights in your rear view mirror.

If an engine didn't have an open port like the road draft tube and filler cap,
at speed/work, the oil pan would become pressurized to the extent that it could deform
or balloon the oil pan.
This especially true of race engines with high lift cams.
At speed/load, Vacating the pressure is a priority.

H): rerouting the "open" hole of the road draft tube has the effect of "tightening up" your engine vacuum under load/work. Installing a regulated valve in the form of a PCV has the effect of regulating drafts(vacuums) and working pressures that build in the crankcase at various engine rpms and loads.
As a side benefit of enclosing or eliminating the road draft tube, your engine vacuum is aided by way of allowing built up pressures in the crankcase to be directed into the intake where the cylinders draw it into the combustion chamber.

The PCV valve in itself is similiar in principle to a common regulator found on things like air compressors and/or oxy acetylene bottles.
:A PCV valve restricts and regulates air flow in one direction.

.

34PKUP · 09-16-2016, 01:21 PM

Quote:

Originally Posted by moefuzz

.

part two, 'Pictures' for this tech article will be up shortly.....

There are many benefits in replacing the road draft tube with a proper Positive Crankcase Ventilation system on your Late model Flathead V8.

A): it helps eliminate the embarrassing smelly/hot fog that wafts out from under your hood at the stop light.

B): It helps to create a consistent vacuum inside the crankcase and oil galleys. An actual vacuum inside of your crankcase will aide in keeping the oil and oily residues from being pushed out from every available seal, gasket or open "hole" that is and/or resides in what we think of as an automobile engine.

C): A PCV system will help eliminate moisture that can and will accumulate in your engine oil and hence your oil pan, engine and intake galleys. Moisture is a major cause of internal engine sludge that builds up (over time) and generally coats all manor of things like intake valves, stems, springs and lifters.

D): When you think about it, The road draft tube is actually just a huge open vacuum leak unto an engine. While a great idea when it was designed, it was obsolete when the idea of a closed System with a proper PCV valve was invented. Having a huge vacuum leak causes your engine to run just a little less efficiently than when not having a gaping hole/road draft tube installed.

E): Eliminating the road draft "hole" and replacing with a proper PCV sets you on the path of creating an enclosed (as opposed to wide open hole) oil galley and crankcase. which brings us to;

F): Eliminating the open hole of the road draft tube shuts out the probability that the road draft tube will (at times) be actually sucking in air/dirt/moisture and debris as you drive along.. To put this into perspective, At idle and part throttle, your engine makes vacuum and the road draft tube is the open end were the internal vacuum can "draft" air into the engine.
At throttle and while working the engine, your engine creates Pressure and this pressure will be pushed out the road draft tube (not to mention and/all gaskets/seals and other non sealed surfaces) and along with the pressure comes hot fog/moisture and oily residues..
Which directly relates to;

G): As you drive/work the engine, the inherent pressure of the working engine escapes from every available seal/gasket etc. and carries with it oily residue that coats your clean engine, engine compartment, firewall, chassis eventually swirling around and being carried away at and around your rear bumper...
...At working pressure, Everything accumulates an oily coating, even the guys headlights in your rear view mirror.

H): eliminating the "open" hole of the road draft tube has the effect of "tightening up" your engine vacuum -in general-.
As a side benefit of enclosing or eliminating the road draft tube, your engine vacuum is increased which in turn helps thing like vacuum wipers work a little bit better as your engine is better able to regulate an enclosed or regulated crankcase as opposed to just having a gaping hole.

----------------------------------------

The PCV valve in itself is similiar in principle to a common regulator found on things like air compressors and/or oxy acetylene bottles.
:A PCV valve restricts and regulates air flow.

In summing up, A regulated air flow thru your engine is far superior to just having the "gaping hole" of a Road Draft Tube as pointed out thru the many benefits as listed above..

.

part two, 'Pictures' for this tech article will be up shortly.....

Wow! and I thought I was confused

petehoovie · 09-16-2016, 01:25 PM

Flathead V-8 Parts : Mercury : Carburetors & Accessories : 1949-53 FORD FLATHEAD PCV VALVE KIT - From JAMCO - http://jamcosuspension.com/products/...productID/1504

click images to enlarge

PCV4953
1949-53 FORD FLATHEAD PCV VALVE KIT

$39.95

1949-53 FORD FLATHEAD V-8 PCV VALVE KIT REPLACES THE ORIGINAL VENT TUBE WITH A MODERN "PCV" VALVE. IT WILL ELIMINATE BLOW BY SMOKE AND KEEP CONDENSATION OUT OF THE CRANKCASE.

moefuzz · 09-16-2016, 01:27 PM

.

First, lets look at a typical 49-53 8BA Flathead V8,
It's road draft tube and the back of the intake at/or under the carb
->where the vacuum line/wipers usually resides.

We're all familiar with the The typical 8BA and it's road draft tube,

Did you know that it's actually just a potential gaping 1 1/4" leak into your engines internals?

At the cap/breather, it's sucking in dust, dirt and moisture, at the road draft tube, it's spewing oily residue into and under your hood.

A quick look at the intake, under the carb at the back....

Most 49-53 intakes will have both the small barb (either straight or 90 degree elbow) for your vacuum wipers as well as this plug pictured at lower right.

This plug is where we are gonna plumb our PCV in at..

----------------------------------------------------

Now, the obvious question here is:
Why not just put a tee into where the wiper tee/port is????

well, you don't want your vacuum wipers and PCV sharing the same vacuum line or port.
The chances of oily residue being transferred directly into your Valuable Vacuum Wipers is high.

-Protect and keep any and all of your vacuum accessories physically separated from your PCV
or risk sludging them up.

So pull the plug from the back of the intake and head over to NAPA and ask the guy
if he can match up and supply you with a 3/8" barb that matches your threaded pipe plug....

While your there, get 2 feet of actual Emission/fuel line,
don't substitute or come home with vacuum line...

Total cost up here was $4 for the above items, prices will vary...

------------

The next stop is the local pic-n-pull where you'll need to find a 70's or 80's Ford with PCV system..

We're looking for the oil breather/cap on the valve cover that holds the factory PCV and it's grommet.

They come as both straight up or 90 degree angled PCV valves and the grommet is the same regardless of straight or angled.

The grommet has a lip on it that will help in snugging up the newly
installed PCV valve into the hole were the former road draft tube used to go.

The actual PCV valve can be found from under the hood of a 4.2 liter V8 as found in many Downsized sedans like the 80's LTD ii, Fairmont, or even a late 70's mustang ll.
Or, One from a 6 cylinder in any 80's small car or truck is also acceptable.

Pic N Pull chargd me $1.

Clean and install the grommet and make sure the inner lip isn't kinked
(as evident here on the left (irregular installed shape/opening))
or the Grommet and PCV valve will have a tendency to walk out as you
motor along.

Install the barb and cut the emission hose to size while keeping the line
tucked down and resting on the top of the block (along side your intake).
On the barb, Teflon tape is optional for brass/pipe fittings but since this is a vacuum line I opted for it. -your choice-

Keep things tidy...

The effects of vacuum/pressure are more pronounced at speed/load.
That is where the engine vacuum drops into a pressure.

At idle with the the new PCV line completely plugged at all ends.
and while simulating an open hole at the road draft tube:

16 1/2 inches of vacuum at 3400 feet above sea level.

With the gaping hole into the galley plugged and the PCV installed,
I gained a little better than 1/2 inch vacuum over the
road draft tube/system open valley.

At speed and under load, while the vacuum drops to zero and the crankcase starts to build pressure is where the real difference will be.

Total cost under $6

.

Chris · 09-16-2016, 01:35 PM

This will be a good read

JSeery · 09-16-2016, 01:45 PM

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Not sure if there is a lack of understanding or it is just how it is written up, but this is not how a PCV works. They do provide many benefits, but not as explained. If anything a PCV system will reduce manifold/intake vacuum.

moefuzz · 09-16-2016, 01:56 PM

Quote:

Originally Posted by JSeery

a PCV system will reduce manifold/intake vacuum.

It will help regulate and restrict it.

JSeery · 09-16-2016, 01:57 PM

Sorry, totally disagree. A PCV system is a controlled vacuum leak into the intake manifold, that's what makes them work.

51 MERC-CT · 09-16-2016, 02:02 PM

Quote:

Originally Posted by moefuzz

.

D): When you think about it, The road draft tube is actually just a huge open vacuum leak unto an engine. While a great idea when it was designed, it was obsolete when the idea of a closed System with a proper PCV valve was invented. Having a huge vacuum leak causes your engine to run just a little less efficiently than when not having a gaping hole/road draft tube installed.

E): Eliminating the road draft "hole" and replacing with a proper PCV sets you on the path of creating an enclosed (as opposed to wide open hole) oil galley and crankcase. which brings us to;

F): Eliminating the open hole of the road draft tube shuts out the probability that the road draft tube will (at times) be actually sucking in air/dirt/moisture and debris as you drive along.. To put this into perspective, At idle and part throttle, your engine makes vacuum and the road draft tube is the open end were the internal vacuum can "draft" air into the engine.
At throttle and while working the engine, your engine creates Pressure and this pressure will be pushed out the road draft tube (not to mention and/all gaskets/seals and other non sealed surfaces) and along with the pressure comes hot fog/moisture and oily residues.. .

H): eliminating the "open" hole of the road draft tube has the effect of "tightening up" your engine vacuum -in general-.
As a side benefit of enclosing or eliminating the road draft tube, your engine vacuum is increased which in turn helps thing like vacuum wipers work a little bit better as your engine is better able to regulate an enclosed or regulated crankcase as opposed to just having a gaping hole

In summing up, A regulated air flow thru your engine is far superior to just having the "gaping hole" of a Road Draft Tube as pointed out thru the many benefits as listed above..

Would like to see the stock road draft tube setup that created any vacuum.

JSeery · 09-16-2016, 02:06 PM

Quote:

Originally Posted by 51 MERC-CT

Would like to see the stock road draft tube setup that created any vacuum.

And with the PCV now you are creating a negative pressure in the crankcase and the inflowing air better be filtered!

51 MERC-CT · 09-16-2016, 02:09 PM

Quote:

Originally Posted by moefuzz

It will help regulate and restrict it.

The primary function of the PCV valve is to close off the back flow to the crankcase in the event of a back fire. Not to regulate flow.

JSeery · 09-16-2016, 02:11 PM

Yep, a lot of confusion going on here.

39 Deluxe · 09-16-2016, 02:16 PM

Agreed, crankcase will not be vacuum, especially considering how leaktight most of our flatties are.

PCV uses vacuum in the intake tract to vent positive pressure from the crankcase and direct it to the combustion chamber. PCV valve only opens at high vacuum conditions (i.e. idling, decel). It does not create a vacuum "leak" per se, as it is regulated by the design of the PCV valve itself. My real world experience is that the PCV system does not have a significant effect on manifold vacuum at idle, nor does it seem to have much affect on idle speed or mixture. I guess if you've got a ton of blow-by, results may vary.

PCV on a flathead, good idea to eliminate draft tube "steam" and oily vapor smells. I wouldn't expect any other improvements.

Also related to this setup....what about sealing the oil filler tube with a non-breathing cap? Or at least a cap that routes vapors to the air filter somehow...otherwise you've still got oil vapor escaping to the car. This would be similar to how Ford did it in the late 60's to 70's.

JSeery · 09-16-2016, 02:20 PM

Quote:

Originally Posted by 39 Deluxe

Agreed, crankcase will not be vacuum, especially considering how leaktight most of our flatties are.

PCV uses vacuum in the intake tract to vent positive pressure from the crankcase and direct it to the combustion chamber. PCV valve only opens at high vacuum conditions (i.e. idling, decel). It does not create a vacuum "leak" per se, as it is regulated by the design of the PCV valve itself. My real world experience is that the PCV system does not have a significant effect on manifold vacuum at idle, nor does it seem to have much affect on idle speed or mixture.

PCV on a flathead, good idea to eliminate draft tube "steam" and oily vapor smells. I wouldn't expect any other improvements.

Yep, but it darn sure doesn't increase manifold vacuum!

petehoovie · 09-16-2016, 02:24 PM

Quote:

Originally Posted by 51 MERC-CT

The primary function of the PCV valve is to close off the back flow to the crankcase in the event of a back fire. Not to regulate flow.

Looks as though the JAMCO unit just evacuates any blow-by out of the crankcase and reroutes it to the exhaust via the intake manifold using vacuum to do so....

OLD AS I · 09-18-2016, 03:47 PM

I saw an article some time ago that suggested putting a common PCV on the underside of the intake manifold, drill a hole and tap suitable to screw the valve in, using a common PCV as is used in GM V8's

Capt Kirk · 09-18-2016, 04:38 PM

Quote:

Originally Posted by moefuzz

.
A): it helps eliminate the embarrassing smelly/hot fog that wafts out from under your hood at the stop light.

Personally, I like when "A" happens. The people in their BMW next to me at the stop light might not...but I don't care.

Kahuna · 09-18-2016, 10:32 PM

As mentioned by J & others, a PCV valve is a controlled air leak

52 Ford · 04-21-2021, 12:07 PM

Thank you for this information. What is the consensus PVC good or Bad overall for the engine?

51 MERC-CT · 04-21-2021, 12:23 PM

Quote:

Originally Posted by 52 Ford

Thank you for this information. What is the consensus PVC good or Bad overall for the engine?

The intention of the system is to prevent crankcase blow-by gasses from entering the atmosphere.
If it were bad for the engine the manufacturers would not be installing them on cars.

V8COOPMAN · 04-21-2021, 01:11 PM

.

This is an old thread, but still a good place to remember a few facts. It's quite possible that PCV valves function opposite of how one might think.

I discovered that PCV valves work in the exact opposite fashion than I had previously believed....check the drawing/chart below! Of course, PCV valves function based on MANIFOLD vacuum produced by the engine. And you should remember that 4-cycle engines normally produce the LEAST amount of vacuum during wide-open throttle (WOT), such as during hard acceleration or 'gettin' on it'! Conversely, the HIGHEST vacuum reading will be experienced at idle, or when the vehicle is traveling on a level surface at a steady speed, and at a constant throttle setting. PCV valves usually consist of a small container with a tiny movable shuttle inside, as well as a tiny spring with varying tension values dependent upon the specific vehicle application. In general, the valve is designed such that the internal shuttle is aerodynamically shaped so that it is able to move in consideration of, and in conjunction with the airflow AND the spring's tension. My biggest mis-understanding in operation was that the valve allows the MOST flow through it as the vacuum reading is at it's lowest, as in WOT (wide-open throttle). The opposite occurs as the vacuum signal increases, like during idle.....when the internal shuttle allows the LEAST amount of flow. This really makes sense when you realize that during WOT (when vacuum is lowest, and the GREATEST flow through the valve is allowed to occur), the largest volume of blowby is being sent past the rings into the crankcase when the highest cylinder pressures are being generated. Inversely, the least cylinder pressure is being produced at idle (when the highest vacuum readings occur), meaning less blowby, and the LEAST flow through the PCV valve.

One more important point....MOST PCV valves are designed to be mounted VERTICALLY, with gravity figuring into the functional parameters. DD

5851a · 04-21-2021, 02:39 PM

The next step for auto makers used an oil fill cap with a hose that led to the air filter housing for any excess fumes. Believe it was called closed crankcase ventilation. Personally I think they work great for keeping engines cleaner. In the later 60's and up when Ford went to the manifold heated air for quicker warm up the air that entered through the oil filler cap was also warmed. Undersides of valve covers were way cleaner in colder climates than in the 50's and 60's. Most of all that comes from emission standards but had an added side benefit. Trouble came when people didn't understand and started ripping things off. Sorry for going OT with this.

51 MERC-CT · 04-21-2021, 02:51 PM

Did a test a while back just to verify the presence of a vacuum in the crankcase.

Zeke3 · 04-21-2021, 03:08 PM

Great looking manometer 51 Merc.

Will D · 04-21-2021, 03:55 PM

Ones says a pcv regulates air flow, the other says it is a controlled vacuum leak.....

Ain't that the same difference? To "control" a vaccum leak is the same as "regulating" air flow(vac leak)....???

34PKUP · 04-21-2021, 04:46 PM

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Quote:

Originally Posted by Will D

Ones says a pcv regulates air flow, the other says it is a controlled vacuum leak.....

Ain't that the same difference? To "control" a vaccum leak is the same as "regulating" air flow(vac leak)....???

The valve does not regulate the flow, its the vacuum created in the intake manifold that controls the position of the valve.

miniceptor86 · 04-21-2021, 06:15 PM

Is it possible in a good engine for the blow by gasses to exceed the vacuum available to keep the crankcase at negative pressure. As in WOT low vacuum and higher blow by? Would this push the gasses back up the inflow tube. Does the inflow need a one way flow provision?

34PKUP · 04-21-2021, 06:32 PM

Quote:

Originally Posted by miniceptor86

Is it possible in a good engine for the blow by gasses to exceed the vacuum available to keep the crankcase at negative pressure. As in WOT low vacuum and higher blow by? Would this push the gasses back up the inflow tube. Does the inflow need a one way flow provision?

If it were a "good engine" it would not have any "blow by gasses" to be concerned with.

V8COOPMAN · 04-21-2021, 06:35 PM

Quote:

Originally Posted by miniceptor86

Is it possible in a good engine for the blow by gasses to exceed the vacuum available to keep the crankcase at negative pressure. As in WOT low vacuum and higher blow by? Would this push the gasses back up the inflow tube. Does the inflow need a one way flow provision?

I would think that with THAT much blow-by, it's probably time to consider a serious rebuild. I would THINK that it would be wise NOT to install any sort of check-valve on the "inflow" tube, as that would serve as a safety, relief feature, but WTF do I know?

Below is a drawing of the route for air movements in a stock 8BA. DD

Ken Henry · 04-21-2021, 08:02 PM

I’ve read that it is normal for crankcase gases to backflow through the breather of fresh air inlet at WOT, since there is very little pressure difference across the PCV valve and that passage is relatively narrow (e.g., 3/8 vs 5/8” or so for the inlet).

markdtn · 04-22-2021, 08:50 AM

I did this pretty much like the OP in case somebody wants new parts with p/ns. The vacuum port just below the carb on my 1950 F1 iron 8BA intake used 7/16 straight banjo threads (not NPT). I bought a GM disc brake 7/16-20 banjo bolt Dorman/Help 13935 or 13947 (and drilled it to a larger ID) and a 7/16 banjo to 3/8 hose barb fitting off Ebay (AKA 12mm banjo x 10mm barb). I am using a Motorcraft EV68 PCV valve and a Dorman/Help 42052 Grommet. Photo is not great but you can see both ends.

Ronnieroadster · 04-22-2021, 11:36 AM

Something to consider. We all know a piston going up into a cylinder is pushing air compressing it along the way. The end gaps in the piston rings allows some of this compressing to leak thus going into the engine crankcase. What also takes place is on the down stroke of each piston additional air is also being pumped into the crankcase. The visual air seen from the breather tube is caused by this air movement into the oil pan. A PCV when installed correctly can reduce this pressure caused by the end gap leaks and the downward movement of the pistons. If these crankcase pressures can be reduced the crank shaft seals will actually work much better due to the reduced pressure trying to push oil out of the lower end of the engine. There's a lot to be gained with a good PCV system.

Ronnieroadster

ajmac · 05-10-2023, 11:14 AM

Although the war years are a bit of black hole when it comes to commercial flathead use, huge numbers were manufactured in Canada and England, not to mention the US for lend lease for Britain. I have a 24 stud 1941 flatty that is lined down to 3 1/16” from the Detroit as Britain had standardised on the 3.6L and only wanted that capacity.
In 42/43 a PCV valve was introduced in Canadian production, it is in the parts book illustration from 1944, there was also a standard extra hole in the bell housing so a full flow oil filter could be fitted as standard. I’ve seen wartime reports that the later engines with PCV were highly regarded in the desert trials as the standard road draft tube engines which also only had the slinger rear crank seal were only lasting 1000 miles between major overhauls!
There was essentially no vacuum generated by the road draft tube in armoured vehicle installations as the engine wasn’t at the front of the vehicle in the air flow. In theory the faster you go in a normal install the more airflow around the road draft tube and the higher the vacuum generated. Note I’m talking about 59A and the earlier 81A, I’ve never seen an 8BA.

scicala · 05-10-2023, 11:28 AM

Disagree on the under $6 part. The PCV valve is probably more than the $6 by itself, unless you're talking about raiding free parts you have laying around.

51 MERC-CT · 05-10-2023, 11:55 AM

Quote:

Originally Posted by scicala

Disagree on the under $6 part. The PCV valve is probably more than the $6 by itself, unless you're talking about raiding free parts you have laying around.

Truly funny, consider this thread started in 2016

Flathead Fever · 05-10-2023, 06:05 PM

Wikipedia history of the PCV valve.

https://en.wikipedia.org/wiki/Crankc...20the%20engine.

When I was a CA smog tech the State tested us to be tested on all the smog devices every two-years to make sure we knew what benefits they provided and how they operated. PCV systems and better oil is how engines can now last 300,000 miles instead of 50,000 miles. They do help the oil from getting contaminated. Blowby gases eventually contaminate the oil which contributes to sludge buildup. I would never remove a PCV system from an engine, but I also would not install one on a vintage engine because I like them period correct. With no oil filter or PCV system I would just change the oil when it starts to look dirty, or every 1000 miles and it should be fine.

Obviously, Ford thought the crankcase needed a road draft tube in 1949 to keep the oil from getting contaminated. That system worked okay but it was dumping that blowby into the atmosphere contributing to smog. I'd rather look at a chromed road-draft tube than a PCV valve on a flathead.

09-16-2016, 12:50 PM	#1
moefuzz Senior Member Join Date: May 2010 Location: Under A Clean V8 Posts: 228	Tech: Cheap and easy pcv on your 49-53 ford flathead v8 . No need to spend $50 bucks on someone's wizzy "PCV" kit, For around $5, you can install a PCV system on your Flathead.. There are many benefits in replacing the road draft tube with a proper Positive Crankcase Ventilation system on your Late model Flathead V8. A): it helps eliminate the embarrassing smelly/hot fog that wafts out from under your hood at the stop light. B): It helps to create a consistent vacuum inside the crankcase and oil galleys. An actual vacuum/draw inside of your crankcase will aide in keeping the oil and oily residues from being pushed out from every available seal, gasket or open "hole" that is and/or resides in what we think of as an automobile engine. C): A PCV system will help eliminate moisture that can and will accumulate in your engine oil and hence your oil pan, engine and intake galleys. Moisture is a major cause of internal engine sludge that builds up (over time) and generally coats all manor of things like intake valves, stems, springs and lifters. D): When you think about it, The road draft tube is actually just a huge open leak unto an engine. While a great idea when it was designed, it was obsolete when the idea of a closed or semi closed System with a proper PCV valve was invented. E): Eliminating the road draft "hole" and replacing with a proper PCV sets you on the path of creating an enclosed (as opposed to wide open hole) oil galley and crankcase. which brings us to; F): Eliminating the open hole of the road draft tube shuts out the probability that the filler cap/breather will suck in air/dirt/moisture and debris as you drive along.. At throttle and while working the engine, your engine creates Pressure and this pressure will be pushed out the road draft tube (not to mention and/all gaskets/seals and other non sealed surfaces) and along with the pressure comes hot fog/moisture and oily residues.. Which directly relates to; G): oily/grime. As you drive/work the engine, the inherent pressure of the working engine escapes from every available seal/gasket etc. and carries with it oily residue that coats your clean engine, engine compartment, firewall, chassis eventually swirling around and being carried away at and around your rear bumper... ...At working pressure, Everything accumulates an oily coating, even the guys headlights in your rear view mirror. If an engine didn't have an open port like the road draft tube and filler cap, at speed/work, the oil pan would become pressurized to the extent that it could deform or balloon the oil pan. This especially true of race engines with high lift cams. At speed/load, Vacating the pressure is a priority. H): rerouting the "open" hole of the road draft tube has the effect of "tightening up" your engine vacuum under load/work. Installing a regulated valve in the form of a PCV has the effect of regulating drafts(vacuums) and working pressures that build in the crankcase at various engine rpms and loads. As a side benefit of enclosing or eliminating the road draft tube, your engine vacuum is aided by way of allowing built up pressures in the crankcase to be directed into the intake where the cylinders draw it into the combustion chamber. The PCV valve in itself is similiar in principle to a common regulator found on things like air compressors and/or oxy acetylene bottles. :A PCV valve restricts and regulates air flow in one direction. . Last edited by moefuzz; 09-16-2016 at 07:01 PM.

09-16-2016, 01:25 PM	#3
petehoovie Senior Member Join Date: May 2015 Posts: 8,244	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Flathead V-8 Parts : Mercury : Carburetors & Accessories : 1949-53 FORD FLATHEAD PCV VALVE KIT - From JAMCO - http://jamcosuspension.com/products/...productID/1504 click images to enlarge PCV4953 1949-53 FORD FLATHEAD PCV VALVE KIT $39.95 1949-53 FORD FLATHEAD V-8 PCV VALVE KIT REPLACES THE ORIGINAL VENT TUBE WITH A MODERN "PCV" VALVE. IT WILL ELIMINATE BLOW BY SMOKE AND KEEP CONDENSATION OUT OF THE CRANKCASE. __________________ The only thing nice about being imperfect is the joy it brings to others.... *"Silver rings, your butt! Them's washers!"* "We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969 https://www.youtube.com/watch?v=7NReUd2_0u0 Last edited by petehoovie; 09-16-2016 at 02:16 PM.

09-16-2016, 01:35 PM	#5
Chris Senior Member Join Date: May 2010 Location: Spokane, WA Posts: 2,976	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 This will be a good read __________________ Thee Inland Emperors

09-16-2016, 01:45 PM	#6
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Sponsored Links (Register now to hide all advertisements) Not sure if there is a lack of understanding or it is just how it is written up, but this is not how a PCV works. They do provide many benefits, but not as explained. If anything a PCV system will reduce manifold/intake vacuum.

09-16-2016, 01:57 PM	#8
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Sorry, totally disagree. A PCV system is a controlled vacuum leak into the intake manifold, that's what makes them work.

09-16-2016, 02:11 PM	#12
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Yep, a lot of confusion going on here.

09-16-2016, 02:16 PM	#13
39 Deluxe Junior Member Join Date: Sep 2010 Posts: 11	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Agreed, crankcase will not be vacuum, especially considering how leaktight most of our flatties are. PCV uses vacuum in the intake tract to vent positive pressure from the crankcase and direct it to the combustion chamber. PCV valve only opens at high vacuum conditions (i.e. idling, decel). It does not create a vacuum "leak" per se, as it is regulated by the design of the PCV valve itself. My real world experience is that the PCV system does not have a significant effect on manifold vacuum at idle, nor does it seem to have much affect on idle speed or mixture. I guess if you've got a ton of blow-by, results may vary. PCV on a flathead, good idea to eliminate draft tube "steam" and oily vapor smells. I wouldn't expect any other improvements. Also related to this setup....what about sealing the oil filler tube with a non-breathing cap? Or at least a cap that routes vapors to the air filter somehow...otherwise you've still got oil vapor escaping to the car. This would be similar to how Ford did it in the late 60's to 70's. Last edited by 39 Deluxe; 09-16-2016 at 02:29 PM.

09-18-2016, 03:47 PM	#16
OLD AS I Senior Member Join Date: Oct 2014 Location: Oakwood, ON Canada Posts: 251	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 I saw an article some time ago that suggested putting a common PCV on the underside of the intake manifold, drill a hole and tap suitable to screw the valve in, using a common PCV as is used in GM V8's

09-18-2016, 10:32 PM	#18
Kahuna Senior Member Join Date: May 2010 Location: NorCal Posts: 2,617	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 As mentioned by J & others, a PCV valve is a controlled air leak

04-21-2021, 12:07 PM	#19
52 Ford Member Join Date: Jun 2019 Posts: 38	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Thank you for this information. What is the consensus PVC good or Bad overall for the engine?

04-21-2021, 01:11 PM	#21
V8COOPMAN Senior Member Join Date: May 2010 Location: East Shore of LAKE HOUSTON Posts: 11,118	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 . This is an old thread, but still a good place to remember a few facts. It's quite possible that PCV valves function opposite of how one might think. I discovered that PCV valves work in the exact opposite fashion than I had previously believed....check the drawing/chart below! Of course, PCV valves function based on MANIFOLD vacuum produced by the engine. And you should remember that 4-cycle engines normally produce the LEAST amount of vacuum during wide-open throttle (WOT), such as during hard acceleration or 'gettin' on it'! Conversely, the HIGHEST vacuum reading will be experienced at idle, or when the vehicle is traveling on a level surface at a steady speed, and at a constant throttle setting. PCV valves usually consist of a small container with a tiny movable shuttle inside, as well as a tiny spring with varying tension values dependent upon the specific vehicle application. In general, the valve is designed such that the internal shuttle is aerodynamically shaped so that it is able to move in consideration of, and in conjunction with the airflow AND the spring's tension. My biggest mis-understanding in operation was that the valve allows the MOST flow through it as the vacuum reading is at it's lowest, as in WOT (wide-open throttle). The opposite occurs as the vacuum signal increases, like during idle.....when the internal shuttle allows the LEAST amount of flow. This really makes sense when you realize that during WOT (when vacuum is lowest, and the GREATEST flow through the valve is allowed to occur), the largest volume of blowby is being sent past the rings into the crankcase when the highest cylinder pressures are being generated. Inversely, the least cylinder pressure is being produced at idle (when the highest vacuum readings occur), meaning less blowby, and the LEAST flow through the PCV valve. One more important point....MOST PCV valves are designed to be mounted VERTICALLY, with gravity figuring into the functional parameters. DD __________________ *Click Links Below* __ ▼ *'35-'36 W/8BA & MECHANICAL FAN* *T5 W/TORQUE TUBE*

04-21-2021, 02:39 PM	#22
5851a Senior Member Join Date: Oct 2014 Location: NE Iowa Posts: 1,666	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 The next step for auto makers used an oil fill cap with a hose that led to the air filter housing for any excess fumes. Believe it was called closed crankcase ventilation. Personally I think they work great for keeping engines cleaner. In the later 60's and up when Ford went to the manifold heated air for quicker warm up the air that entered through the oil filler cap was also warmed. Undersides of valve covers were way cleaner in colder climates than in the 50's and 60's. Most of all that comes from emission standards but had an added side benefit. Trouble came when people didn't understand and started ripping things off. Sorry for going OT with this.

04-21-2021, 02:51 PM	#23
51 MERC-CT Senior Member Join Date: May 2010 Location: East Hartford, Ct Posts: 5,898	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Did a test a while back just to verify the presence of a vacuum in the crankcase. __________________ DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES

04-21-2021, 03:08 PM	#24
Zeke3 Senior Member Join Date: Dec 2014 Location: Columbus, IN Posts: 1,407	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Great looking manometer 51 Merc.

04-21-2021, 03:55 PM	#25
Will D Senior Member Join Date: Feb 2020 Location: BC Canada Posts: 573	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Ones says a pcv regulates air flow, the other says it is a controlled vacuum leak..... Ain't that the same difference? To "control" a vaccum leak is the same as "regulating" air flow(vac leak)....??? __________________ Sometimes, ingenuity gets in the way of sense and sanity.

04-21-2021, 06:15 PM	#27
miniceptor86 Senior Member Join Date: Aug 2019 Location: McGregor, IA Posts: 233	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Is it possible in a good engine for the blow by gasses to exceed the vacuum available to keep the crankcase at negative pressure. As in WOT low vacuum and higher blow by? Would this push the gasses back up the inflow tube. Does the inflow need a one way flow provision? __________________ Cheers, Jim&Sandy McGregor, IA

04-21-2021, 08:02 PM	#30
Ken Henry Senior Member Join Date: Jul 2010 Location: Rochester, NY Posts: 266	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 I’ve read that it is normal for crankcase gases to backflow through the breather of fresh air inlet at WOT, since there is very little pressure difference across the PCV valve and that passage is relatively narrow (e.g., 3/8 vs 5/8” or so for the inlet).

04-22-2021, 11:36 AM	#32
Ronnieroadster Senior Member Join Date: Dec 2010 Location: East Coast in CT Posts: 1,537	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Something to consider. We all know a piston going up into a cylinder is pushing air compressing it along the way. The end gaps in the piston rings allows some of this compressing to leak thus going into the engine crankcase. What also takes place is on the down stroke of each piston additional air is also being pumped into the crankcase. The visual air seen from the breather tube is caused by this air movement into the oil pan. A PCV when installed correctly can reduce this pressure caused by the end gap leaks and the downward movement of the pistons. If these crankcase pressures can be reduced the crank shaft seals will actually work much better due to the reduced pressure trying to push oil out of the lower end of the engine. There's a lot to be gained with a good PCV system. Ronnieroadster __________________ I use the F word a lot no not that word these words Flathead , Focus and Finish. "Life Member of the Bonneville 200 MPH Club using a Ford Flathead block" Owner , Builder, Driver of the First Ford Flathead bodied roadster to run 200 MPH Record July 13, 2018 LTA timing association 200.921 in one and a half miles burning gasoline. First ever gas burning Ford flathead powered roadster to run 200 MPH at Bonneville Salt Flats setting the record August 7th 2021 at 205.744 MPH

05-10-2023, 11:14 AM	#33
ajmac Member Join Date: Nov 2012 Location: Lincoln, UK Posts: 50	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Although the war years are a bit of black hole when it comes to commercial flathead use, huge numbers were manufactured in Canada and England, not to mention the US for lend lease for Britain. I have a 24 stud 1941 flatty that is lined down to 3 1/16” from the Detroit as Britain had standardised on the 3.6L and only wanted that capacity. In 42/43 a PCV valve was introduced in Canadian production, it is in the parts book illustration from 1944, there was also a standard extra hole in the bell housing so a full flow oil filter could be fitted as standard. I’ve seen wartime reports that the later engines with PCV were highly regarded in the desert trials as the standard road draft tube engines which also only had the slinger rear crank seal were only lasting 1000 miles between major overhauls! There was essentially no vacuum generated by the road draft tube in armoured vehicle installations as the engine wasn’t at the front of the vehicle in the air flow. In theory the faster you go in a normal install the more airflow around the road draft tube and the higher the vacuum generated. Note I’m talking about 59A and the earlier 81A, I’ve never seen an 8BA. __________________ Alastair --------------- Loyd Carrier - Under Restoration Loyd Project on Facebook

05-10-2023, 11:28 AM	#34
scicala Senior Member Join Date: Jun 2010 Location: Detroit suburb, MI Posts: 3,706	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Disagree on the under $6 part. The PCV valve is probably more than the $6 by itself, unless you're talking about raiding free parts you have laying around.

05-10-2023, 06:05 PM	#36
Flathead Fever Senior Member Join Date: May 2010 Location: Yucaipa, CA Posts: 1,096	Re: Tech: Cheap and easy pcv on your 49-53 ford flathead v8 Wikipedia history of the PCV valve. https://en.wikipedia.org/wiki/Crankc...20the%20engine. When I was a CA smog tech the State tested us to be tested on all the smog devices every two-years to make sure we knew what benefits they provided and how they operated. PCV systems and better oil is how engines can now last 300,000 miles instead of 50,000 miles. They do help the oil from getting contaminated. Blowby gases eventually contaminate the oil which contributes to sludge buildup. I would never remove a PCV system from an engine, but I also would not install one on a vintage engine because I like them period correct. With no oil filter or PCV system I would just change the oil when it starts to look dirty, or every 1000 miles and it should be fine. Obviously, Ford thought the crankcase needed a road draft tube in 1949 to keep the oil from getting contaminated. That system worked okay but it was dumping that blowby into the atmosphere contributing to smog. I'd rather look at a chromed road-draft tube than a PCV valve on a flathead.