pcv on early ford?

Jack E...I was going to put the outlet in the tube below the cap, not on the cap itself, so the rubber pipe can be secured more easily.

I also wondered if the 1932 block has sufficient breathing as standard. Does the filler tube go into the lifter valley? Is that the only breather?
 
Tom Walker said:
I also wondered if the 1932 block has sufficient breathing as standard. Does the filler tube go into the lifter valley? Is that the only breather?
Click to expand...

I don't know the answer, but always presumed that the Flathead had a road draft tube from the very beginning... having said that unless you are driving along the fumes are just as likely to come out of the filler cap vents as the draft tube.
 
1932-4 are considered vented...meaning there was a hole (the filler) for pressure to relieve itself as needed. Parenthetically, I have seen a 1930's picture of a '32 racer with tin pan BULGED from blow-by...
1935-end are ventilated...meaning there was a effort to generate organized movement of air through innards, from vent cap filter round and round then out the vent on pan, propelled by road draft and faith. An effort to move vapors, especially all the water, out better.
PCV replace the road vent at bottom with a definite directional flow from vacuum.
Mixture control was kept within reason by restricted flow...on the wartime Fords the restrictions were in the under-carb adaptor, two very small holes drillded through to pull from both sides of manifold. Modern systems generally have the restriction integral with manifold side of the PCV, one reason there are so many models...they have to relate to engine displacement and flow at idle.
The wartime setup was similar to the patent shown...valve was outside the valley, vertically mounted downward from RF of carb, pickup was above the front draft tube but not sealed onto it as the patent one seems to be.

(for the carrier and military flathead fans...the PCV system is shown pretty well in the Canadian manuals for vehicles built for British MOD from about 1942 on. Earlier editions showed the stock 1835-up ventilation system.)
 
Speaking from experiance on a different flatty...I have installed pcv valves on continental 4 cyl in sa200 welders and have used them for years.They usually run a minimum 8 hrs a day,on big pipe the little engines run very hard....The pcv valve makes the difference between a leaking rope seal and a sweating one!Some jobs they are very persistant about haveing no leaks and this helps alot.
 
Positive Crankcase Ventilation (PCV) is probably one of the most misunderstood function and purpose, relative to the internal combustion engine.
The military in the early '40's saw fit to equip many of the engines used in confined areas, tanks, etc., with closed crankcases to eliminate fumes within the crew compartment.. Closed crankcases were also needed on vehicles that were equipped with "fording" (water crossing) systems.
All vehicles manufactured since 1963 must have closed crankcases, i.e., PCV..
OK, All of the above said, just how hard is it to install a PCV system on pre '63 vehicles? It is not that hard if you use the "KISS" principle.. Keep It Simple Stupid.. The first step is to close off the crankcase vent which is located in the front left hand corner of the early V8 pans.. Then a source for vacuum must be provided.. The vacuum source should be large, about 3/8".. This can usually be found at the base of the carb..
In the Ford V8 flathead engines a hole must be drilled into the forward portion of the intake manifold, that extends into the lifter/valve chamber.. The hole has to be threaded to receive a pipe threaded fitting for the hose to the vacuum port..
An 8BA engine is a little easier because of the draft tube that enters the front portion of the intake manifold.
The proper size PCV (from the same CID engine) is installed into the hose... An option is to use the type of PCV that will thread directly into the manifold..
A vented cap is then used on the oil filler standpipe.. An option is to use the type of cap that has a hose connection made into the cap.. A hose is then ran to a hose fitting that has been installed in the carp air cleaner..
Vacuum will pull fresh air through the filler cap and through the engine. Fumes, etc., will enter the intake/combustion chambers, mixing same with the fuel air mixture..
In many cases the carb will have to be leaned out because the crankcase vapors will cause the fuel to be on the rich side..
The size of the PCV is very important because it must snap shut under acceleration, so that there is vacuum for the advance on the distributor.
Many years ago there was an article published in the V8 Times detailing the installation of a PCV in an early flathead V8... The only problem with the system in the article was the placement of the PCV.. Under the intake manifold.. True the system was not unsightly, however, the intake had to be removed to service the PCV...
 
I still dont think its a good idea to introduce a supply of air in between the carb and the engine. I dont really see the difference between doing that and ,say, removing a blanking plug from the manifold which as we all know wreaks havoc to your mixture.

Plus you are by definition resticting the flow you can draw from the crankcase. On that patent diagram, the size of the pipe is so small as to make me wonder how much effect it would have.

If you seal the oil filler tube, say, which is also the breather, and feed it somewhere into the air filter, there is always negative pressure there, and more when you floor it, which coincides with the increased "breathing".

We could go on to discuss the benefit of creating a vacuum in the crankcase to reduce windage losses, one-way valves etc (a knock-on is reduction in oil leakage), but this is only for the "8,000 rpm and up" boys is'nt it?
 
The flow through the valve is really quite small compared to what the engine uses. The analogy to an open plug in the manifold is not even close to being relevant.
 
The flow is restricted by design by a small area in valve or passageways, easily compensated by normal idle tuning and probably irrelevant above idle. Also, from a discussion back when the PCV's became standard circa 1962, that air contains tiny amounts of burnable hydrocarbons from blowby and oiling fumes and may not even be a leaning-out factor!
A factor to remember is that PCV may be increasing air flow through the filler cap and adding a better air cleaner there (Especially for '32-4!) would be a good idea.
The wartime engines got an oil bath filter installed there, nearly as big as a normal flathead carb filter. The actual intake got the huge truck accessory type oil bath, as heavy truck and armored carrier engines mostly lived at full throttle...
 
Also consider that blowby is greatest at throttle positions where a PCV valve suction is lowest/zero and air-cleaner PCV entrainment is highest. This is primarily why I didn't bother with the additional complexities of a valve for low throttle PCV but rather rely on entrainment only with a filtered open crankase to reduce interior crankcase fumes & stink at all throttle positions. It works. The only caution in using an entrainment system is to install large enough diameter connections (as David J already pointed out, it is not an aggressive PCV) and a flame-arrestor somewhere between the air-cleaner body and the crankcase. I use 1" id tubing filled with stainless steel scouring mesh.

Jack E/NJ
 
I read a book that covered pcv setups and the best setup has 2 basic elements. first is a pcv as we all understand it, plumbed to the carb base or another manifold vacuum source. This serves well for all idle/ normal driving situations. For WOT operation, a pipe plumbed in to the base of the air filter serves betteras with little or no manifold vacuum the first setup will not be very effective, but because of the pressure drop caused by the air filter, the filter base mounted pipe will take over and draw the fumes in when (at wide throttle) blowby is at it's most.

I have a hidden inlet manifold based setup on my roadster, it serves well at helping reduce leaks and keeping things clean.

Mart.
 
The only "late model" type I am really familiar with covered the problem in both directions...PCV hooked up to vac sorce, then the intake side of the system was plumbed up to the air cleaner can with its own little filter within. That would be simple to duplicate but hard to make look good in an early car...
From memory, the early '60's PCV systems with their filters in the breather caps became known later as "open" PCV, while the late 1960's up ones with hosiery up to carb air cleaner were the "closed" stle since they took care of any flow from blowby or pressure rise inside the engine.
 
Mart said:
I read a book that covered pcv setups and the best setup has 2 basic elements. first is a pcv as we all understand it, plumbed to the carb base or another manifold vacuum source. This serves well for all idle/ normal driving situations. For WOT operation, a pipe plumbed in to the base of the air filter serves betteras with little or no manifold vacuum the first setup will not be very effective, but because of the pressure drop caused by the air filter, the filter base mounted pipe will take over and draw the fumes in when (at wide throttle) blowby is at it's most.

I have a hidden inlet manifold based setup on my roadster, it serves well at helping reduce leaks and keeping things clean.

Mart.
Click to expand...

Mart, I'd be interested to know if you have any other kind of crankcase breather other than the one you describe above.
 
Modern pcv valves come in three types. Fixed orifice, valve that increases flow as vacuum drops, and fixed orifice plus valve that opens as vacuum drops. The valve works by vacuum holding it closed against a spring and as vacuum drops the sping opens the vave. The valve type are the ones that rattle when you shake them until they get gummed up and don't rattle.
 
Bruce Lancaster said:
Another possible can of worms for the labyrinthe worries:
Smokey Younick in one of his articles on engines reported that there was a very substantial windstorm going on within flywheel housings of engines...enough was happening in there that he speculated a bit about tapping into this area as a source of supercharging!
So...I suspect this means we don't really know what might be passing through the labyrinthe already, or even which direction the worms might be crawling as they exit the can...
Click to expand...

I was researching old threads about PCV and 21 stud engines and this caught my attention in particular. Has anyone put a check valve on the vent at the clutch housing so that it can only exhaust thereby minimizing what can be forced into the engine through the labrynth seal?

The oil pan and block flanges where the trans attaches are not flat so a shim and gasket would not add much effort in my case (need shim anyway) and that would seal the clutch housing. I am thinking something simple like a flat plate that blows open and seals on a thin foam seal or similar. Any thoughts?
 
Rather than running a PCV valve I am considering this. 1. Install freeze plug on draft tube hole in the intake manifold. 2. Tap a fitting into the fuel pump stand. 3. Weld a short steel tube into the passenger side exhaust pipe just after the exhaust manifold. 4. Install a rubber hose from the fuel pump stand to the steel tube. The question would be what size. Probably 3/8". No need to size a valve and there would be a constant draw from the exhaust at all RPMS.
 
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