Technical pcv valve? or not

A carb doesn't care if you are running a PCV or not, you just plug the hole.

 

Back in the day when I was a kid most engines where burning oil by the time they had 70,000 miles on them. It was rare to see an engine that had a 100,000 miles. In 1963 almost every car built had a PCV from the factory. And we began to see engines last way past 100,000 miles. I retro fit a PCV on everything I own. However My 1944 M farmal tractor has a crankcase breather tube. It also has a factory tube running from the rear of the cyl head to the inlet of the air cleaner. Its on LP and has never been torn down or had any engine work. Its a rare engine that wouldn't have positive benefits from a PCV system.

 

Old Wolf,
This is just a guess or theory on my part but I think that a PCV could be installed on an old engine and slow the oil consumption way down. One of the things that can cause oil consumption is ring flutter and less crank case pressure can lower ring flutter a bunch.

Unfortunately we are not there with a PCV valve to test my theory but it is something to think about.

 

Yup, it's all about how many miles you expect it to last. If you only drive it a thousand miles a year, it'll outlive you without PCV.

 

I just put a nipple on high on the back of one of valve covers, near the firewall, then ran an inline hose pcv valve. Did the same on the other side, but ran the hose up the firewall to a small hidden motorcycle filter. You can barely see it. Seems to be working pretty well. Its not rocket science, get creative.

 

This is a 383 I built a while ago. I´ve put in a baffled pcv valve between carb and distributor and the oil fill tube work as a breather.

 

one thing also to consider . there is no such thing as a universal pcv valve , the valves are weighted to a specific vacuum point ( flip them over and you see letters on the weight ) and should be matched to the camshaft the motor uses, a low vacuum producing cam you want a valve from a late 60's hi perf motor , a stocker hyd type cam one from a grocery getter style car . otherwise you can wind up pulling massive ammounts of oil or not clearing the crankcase good enough . a good operating system will have a slight pull on the valve cover or oil fill tube at all times . the Pcv also works backwords of a radiator cap as when you lower the pressure in the crankcase it makes the condensation boil at a lower temp and that helps keep the oil from forming acids and sludge . I prefer to mount mine in the location like Pontiac used to help lower oil consumption and thats above the lifter box in the valley . the rockers boxes are filled with flyin oil that even when baffled have a hard time controlling

 

BAumi has the right Idea .

old wolf the reason why the tractors lasted longer was they always ran for long periods at a steady rpm ( changing rpm changes the fuel stioch and it sometimes overfuels which creates contamination one reason why cars with Hwy miles oil last longer ) and warmed up the oil real good , and most of the oils we used were straight weights and low ash oil that the dealer sold . and the pistons were cast iron and the blocks were of a real strong alloy ( as most were structural members on most )

 

Baumi, did you use a baffled rubber grommet for the pcv or a special type of shielded pcv? I'm doing the same thing-ready to drill the hole in the same place near the coil mount with the oil tube up front. Thanks, Sam

 

Any thoughts why Edelbrock specifies the use of the front fitting on their carbs for the PCV?

 

Sam, I made a little tin baffle I attached with two little screws from underneath the intake manifold over the hole where the PCV valve enters. Just to avoid oild splashing directly into the pcv valve. I doubt there´s a as much oil flying around in the lifter valley as there is under ther rocker covers. Anyway this engine has about 50k miles on it now an no leaks and no recognizable oil consumption between oild changes so far. I just don´t like the look of the new style rocker covers with the breather holes in them, I love the look of the sleek old valve covers... so came up with this...

 

Baumi, thank you. I have a large journal 327 and an original unmolested pair of the finned aluminum valve covers. with no holes. I had considered drilling completely through the coil mount towers in order to mount some type of splash shield but I like your approach. Thanks again.

 

Here is the setup that has always worked well for me. Intake breather and breathers in each valve cover. No PCV valve.

 

Mine was very well disguised. My block had the roaddraft hole and I used that. I think the air going in or over the front fill tube either pushed air through the PCV system taking oil with it, or created a vacuum pulling oil out of it. Over a certain speed I would get oil all over the windshield. Could also just be more preasure in the engine than the pcv can handle. Now that I don't run one I only get a little smoke out the breathers when I stop after running hard.

Doesn't the PCV valve only work in higher vacuum situations? So when your off the throttle and at idle. Doesn't your engine get sludged up when your cruiseing? I always thought they were for sucking up the blowby when you stopped at a light so your car wasn't smoking/stinking out the roaddraft tube. Then the detergent oil cleaned out your sludge.

 

The valve only works when it has vacuum yes. The rest of the components of "positive crankcase ventilating system" work all the time if it's similar to OEM. Check out mad Mikey's picture. When you flat foot the loud pedal there's no vacuum, and if crankcase vapor pressures build they go up the fresh air intake tube and get sucked down the throat of the carb.

Just Cruising is a high manifold vac condition

 

A couple of breathers is better than nothing. It will at least tend to keep excess pressure from building up in the crankcase. They just don't do much to actually remove moisture and blowby. That's where adding a draft tube or PCV valve will do a better job.

 

We were ridded of road draft tubes as technology improved and the PCV was invented. It is a much better way to vent the crankcase, no more smells, and with a road draft tube there is always foreign material getting into the crankcase. Engine life was greatly improved. Get over not looking period correct and use it

 

Not to mention the roads aren't oil soaked either.
Ever notice in old photos the black zone in the center of the lanes?

 

also notice most passenger side floors on older cars found up north were not rusted either ??? ( rust proofed the floor bottom and crossmembers ( my frame on my 50 when I had it cleaned turned the caustic vat black when we dipped it in )

semis are now using a PCv style system after having road draft tubes for years , I hated crawling under the truck as the oil dripped down from the front axle or oil pan . specially Cats right after you changed the oil .

 

My tractor is a LP version. With LP you don't get combustion deposits or contamination in the oil. As long as you service the air cleaner and don't let the engine breathe dirt a LP engine wont hardly ever wear out. Ive got 4 M farmall tractors only one is LP. My gasoline versions do wear out and start burning oil and need rings or new sleeves & pistons about every ten years. Its my opinion that a PCV does indeed help a engine last longer. And now the fuel injected engines should last longer because of the precise fuel metering and improved combustion.

 

we had a miny mo propane unit and it would water up the crankcase as propane made more water vapor , that was a sludge monster unless you ran it hot and for 20-30 minutes minimum . but still you would have more water condensation than a gas motor in the oil . and our minny mo would eat rings , it was from the fuel being dry and offered no real lubrication , the pistons when it was rebuilt we used tin plated ones ( the guy who did our tractor did lift trucks ) and never had any bore wear problems after that .
as for the new engines the fuel metering has lots to do with longevtivity , but also the hotter running temps they use . most new vehicles including semis ( which used to run between 160-180 * are now running 195-205* minimum on the water temps ) . which makes the oil run warmer and helps keep the vocs at bay too . ( used to have to change oil in my old Cats at 10K miles now its 25K per Cat) .

 

Something was wrong with the setup on your Moline. A gas is a gas No logical reason that LP would be any dryer than gasoline. would I had a model U Moline on LP and never had any problems. You need a working thermostat in the water neck. and hot water lines flowing through the regulator. the regulator needs to be set up properly for the engine. the bottom oil ring is what keeps the cyl walls lubed with oil. I would bet your engine was getting too much liquid and not enough vapor. The excess liquid was washing down the Cyl walls. The big natural gas engines that generate electricity hardly ever get oil changes. They take samples of the oil and only change it when it gets contaminated to a certain level.

 

No, actually the valve opens the most under "medium" vacuum conditions (cruising). The valve closes (not necessarily all the way) if vacuum is too much or too little.

Sludge is caused by emulsion of oil and water (think mayonnaise). PCV is designed to get the water from condensation out of your crankcase. The removal of stink is just an added benefit.