Oil Problem

[29Coupe348]

ok, heres the problem...this is the third time this has happened to me...im on the highway, at about 2800 rpm, and all of a sudden OIL, and lots of it all over the windshield, as far as i can see its comming out of the breather/oil fill tube...but the weird thing is it dosent happen all the time, im on the highway alot, and its only happened 3 times....i changed the pcv valve...what else????...a cracked ring, a ring hanging up, the wrong pcv valve????what????im using a pcv valve for a 64 409....thanks,mike

[Ronnie Russell]

Coupe, Have you got a road draft tube, or have you plugged it because you are using pcv valve? You cant have enough breathing, if you dont have road draft tube--get one. You can also try add-on breathers inthe valve covers. What ever it takes,,, you need to bleed off the crankcase pressure.

[29Coupe348]

i have the pcv where the road draft tube would go, and i really dont wanna put holes in my offy valve covers....i was thinking about nixing the pcv thing, and going back to a road draft tube.

[JimKwiatkowski]

I had the same problem blowing oil.I repaired my problem with a new oil filler cap.

[29Coupe348]

thats my next step, i have had the same cap on for the past 3 years...kool, thanks jim...,mike

[29Coupe348]

what PCV valve part# should i use?????

[rcurrier44]

I have seen severial engins that have drain problems ware you are running at a high enough RPM long enough that it is pimping more oil to the top of the heads than can drain back down. Eventualy it comes out the breather and gets all over the place.

[Mr Goodwrench]

I'm using a pcv valve for a 400 pontiac on my set up. the side that goes to the carb is 3/8" the side that goes to my oil fill tube is 1/2" thats pretty close to the way the factory was. I tried three of the stock ones, they all pulled my manifold vacume down from about 18.5 inches to 15 inches. carb wouldnt work right, and it ran like crap.

[29Coupe348]

kool, thanks....im using one from a 65 409.

[Ronnie Russell]

I have decided to comment on pcv valves.Sit down and get comfortable, this will take awhile. First , I decided to google pcv valves so I could have an accurate definition. Here it is ;;; The pcv valve is an emission control device that routes unburned crankcase blowby gases back into the intake manifold where they can be re-burned. Besides totally eliminating crankcase emissions as a source of pollution, the constant recirculation of air through the crankcase helps remove moisture which would otherwise cause sludge to form, thus the pcv valve extends the life of the oil and the engine. Who wrote this ridiculous stuff? Who believes this ridiculous stuff? True, it routes unburned blowby gasses back into intake manifold. what is blowby gasses? OIL MIST under pressure. I dont want to burn an oil mist, I want to burn gasoline. If I wanted to burn oil , I would buy a 2 cycle motor. Totally eliminating crankcase emissions? Nothing is total. Constant recirculation of air through crankcase? Guess I have overlooked that device. Where does that fresh air come from that is constantly recirculating in my crankcase? The intake manifold sucks the crankase pressure(oil mist) and impurities through the pcv valve and into combustion chamber. The pcv valve is supposed to open and close -controlled by engine vacuum. They all leak!!!! Even new , they leak. A controlled vacuum leak and sometimes an unconrolled vacuum leak. Ever tear down a pre-computer motor and see the pistons and valves covered in black carbon gunk? Think to yourself " My, these rings must be worn out, or My, these valve seals must be shot" Did you ever think what burning an oil mist for 50,000 miles does to the inside on an engine? You all know what oil does inside a combustion chamber. Back then we had real gasoline,with true octane, today we have junk gas. Do you really want to dillute your junk gas with oil mist? Forget about positive crankcase ventillation. Use a whole lot of negative crankcase ventillation. Burn gasoline , not oil and get rid of those vacuum leaks . Can anybody guess how I feel about pcv valves? Thanks for your patience and time.

[29Coupe348]

i had my heads off over the winter, and the tops of my pistons were black, now i know where it came from....so your saying you would reccomend a draft tube????...lol.

[Ronnie Russell]

Coupe Try a new breather cap , as JimKwi suggested .If you still oil up your windshield , try a road draft tube . Is nt the road draft tube a much bigger diamiter than the 1/4 in. opening in the base of the carb where the pcv attaches? Do what you gotta do to eliminate excessive crankcase pressure. If all attempts fail, then the rings must be worn badly .

[SS425HP]

Ronnie, quit beating around the bush and give us your true feelings on PCV valves. :rofl :rofl :rofl

[fatride]

I have ran a PCV valve on my 348 and now on my 409 with no negative effects so far. Runs and idles fine! Good for street engine I think. Road draft tube would work too I will guess, did for years. I prefer the PVC for my engine, just seems neater. I think PVC would eliminate more moister and keep the inside of the engine a little cleaner. This brings up food for thought. I guess if we really want to evacuate the crankcase of crap we could all get the Moroso setup that uses the exhaust collector to create a vacuum and reduces crankcase pressure. :scratch

[Ronnie Russell]

Dead on right , Ray... The evacuators plumbed into header collectors are the best for positive crankcase ventilation. Unfortunately , it is not practical for most street applications.

[walkerheaders]

these days the trend is moving toward vacuum pumps for crankcase evacuation. i have installed many of the Moroso kits on customer cars, all with impressive results. not only do they help to add power, they even help with oil leaks and ring sealing.
alot of racers dont stop to think that if you have 409 inches in the cylinders, then you also have 409 inches moving violently in the crankcase.
I always used the pan-evac system on my 470 BBC and never had a problem. but in a dragboat, the headers are behind you. at least i never saw any oil discoloration in the collectors? I always use 60W valvoline in the 470 (aluminum rods)
My 409 car uses the pcv on the rear carb and draws fresh air thru the air filter. i have turned this setup as high as 7200 with no blowby troubles. 6000-6500 rpm with my current combination. still no evidence of any trouble.
however, i may try some alternate ideas and see what happens.
even though Ronnie sugar coated his true feelings about PCV, he gave me some ideas.

[Ronnie Russell]

Bob, thanks for your comments. I , in no way , meant that pcv systems "causes" blowby problems. My point is very simply, The crankcase gasses and impurities that go out of an engine via road draft tube and onto the road or instead directed into the intake manifold. The loss of power ( if any) is not noticed by the driver. The gasses and impurities are mixed with fuel and burned. Cleaner for our enviroment for sure. I just prefer not to burn the crankcase gasses and impurities in the combustion chamber. Pcv systems cannot be a problem because this is the first discussion I have ever seen on the subject. Must be the weird way I look at things. The "trash" that used to go on the roadway, now goes into the combustion chambers" I just dont know any other way to look at it.

[Mr Goodwrench]

coupe I have a feeling you have excessive blow-by from a worn out engine, I believe a few posts earlier you made mention to that, please correct me if I'm wrong if that is the case neither a pcv valve or a draft tube will help you. your best bet I think would be a pcv valve on a closed system like the 409-425 used, in other words a sealed oil fill cap insted of the push on breather cap. the closed system has a hose coming from the oil fill tube and going back to the air cleaner. I had the same problem on my truck because alot of the miles I put on it are at WOT where there is no vacume to make a pcv valve work. I know what it's like to breathe that crankcase vapor, used to fill the inside of my truck up even made your clothes stink like you've been running an engine inside a closed garage.

[JimKwiatkowski]

Goodwrench,I use a sealed oil fill cap and breather caps on both valve covers with a PCV valve.I think 29 has 3x2 with small air cleaners,so he can't run a hose from the filler tube to the air cleaners.I think 29 needs to run a sealed oil fill tube and a road draft tube,if he does have a ring problem he should have alot smoke coming from his draft tube and no oil on his windshield,this will fix the oil on the windsheild till he can get a new short block.

[threeimpalas]

A road draft tube is going to get that A-bone all gunked up in place you don't want it to (ie; the underside of the car). Stick with a PCV setup.

[Ronnie Russell]

Mike, "all gunked up in place you dont want it to ( ie; the underside of the car) ??? So you had rather force that "gunk" into the intake manifold? Im sorry guys, I give up. I guess I cant see the forrest for the trees. I will leave it alone, dont want to lose good friends because of a pcv valve.

[JimKwiatkowski]

Ronnie,there's no need to be sorry,you told us the facts and it's up to 29 if he wants his windshield gunked up or his underside :dunno

[29Coupe348]

well, i changed the breather , and it happened again today....now, im going with the road draft tube, till i get my new motor over the winter...thanks,mike

[johnnyrod]

Could we not plumb it like on the 327 250 hp engines. PCV valve from a sealed filler tube to base of carb and a road draft tube from the rear of the engine to the air cleaner that line is about 1/2 inch or even bigger. Just a thought feed back please. John

[Ronnie Russell]

Johnny, I think the key is " base of carb'. What is going through that hose? Where is it going? The later systems went to the air cleaner base and had square mesh filter to stop the big stuff. That wouldbe better. But you still gotta ask yourself, ' what is that stuff going in my carb? expended gases? OIl? impurities? This aint a big deal. millions used with good effects. Keeps that stuff from going in the air. But does an engine make the same horsepower with straight gasoline or with gasoline mixed with "stuff"? Each person must make their decision as they see fit.

[jester]

Are the oil return passages clean ? All theese motors are plumbed in similiar way and yours is the first I have heard of. I wonder if there is an over abundent amount of oil remaining in the lifter galley from the extended higher RPM.
Just a thought .

[CHEV601234]

29,

You said you have your pcv mounted where the road draft tube would go. If that's true, you'd have a hose to the base of the carb or a fitting on the intake. If that hose is soft or swelled, the engine vacuum can be partially collasping it, and allowing the crankcase pressure to build, until it finally "burps" back out the filler neck. Mount the pcv on the carb base or a fitting on the intake, and route a new hose from an adaptor (where the road draft tube would mount) to the pcv.

As for what's going into your engine, if you have a street car, rather than a race car, the blah, blah, blah about pcvs is merely achedemic. It didn't help you solve your problem. Chevrolet provided millions of customers with cars fitted with pcv systems and they ran many trouble-free miles.

[29Coupe348]

i have a solid stainless steel line running fron the back of my carb, and like a 2" peice of hose to the pcv valve, its not soft or swelled....i dont understand what you are saying, you want me to mount the pcv directly to the carb???how the hell do i do that??????

[Ronnie Russell]

chev601234, You are exactly correct. "If you have a street car, rather than a race car"-- blah-balh-blah. I assume blah-blah-blah means performance is not an issue. The pcv system is the first mass=produced emissions control device mandated by the government. Millions of customers with cars fitted with pcv systems ran many trouble free miles. No argument about that, they had no choice. 29, I have no idea where your pcv valve is mounted. 60 is correct about its location. carb base or intake man. fitting that is pulling vacuum. Ive never seen one stuck in the back of an intake, but I havent seen a lot of things. That is why I suggest you use a road draft tube and see if you still throw out oil.

[threeimpalas]

Mike, "all gunked up in place you dont want it to ( ie; the underside of the car) ??? So you had rather force that "gunk" into the intake manifold? Im sorry guys, I give up. I guess I cant see the forrest for the trees. I will leave it alone, dont want to lose good friends because of a pcv valve.

Considering that his A is a fenderless street rod, and not a race car, I imagine that he'd rather not have the car be continuously covered in oil mist and the other crud said oil will attract to the underside of his show car.

In my case, the '59 SD is a "show car", uses a PCV valve, and can still roast the tires when the need arises. It performs flawlessly with no blow-by, no oil mist where it shouldn't be, and gets excellent gas mileage for the technology of the engine.

Given that a properly functioning PCV setup will still allow the engine to perform acceptably, I don't see why one would want to use a road draft tube in such a car.

[Ronnie Russell]

Mike, your 59 SD is a beautiful wagon. Did it come with a pcv valve? If not, I applaud you for adding one and helping to keep our air clean. Your quote of " Given that a properly functioning pcv setup will still allow the engine to perform acceptably etc." That is the differance between "show car guys and race car guys" Performance is never acceptable to us, we are always looking for more. A 74 Cadillac 4dr deville will roast the tires. As far poor old 29, seems he will oil the bottom of his show car or oil the windshield. At least with a road draft tube, he can see where he is going.

[mpris]

My 64 409/425 came with what is called a positive engine ventilation system (option K24). It has always been my understanding that this system does not have a PCV valve in the back of the front carb, but a PCV orifice of a fixed size. At the rear of the engine where the road draft tube would normally be, there is a metal pipe with a short rubber hose connected to the base of the air cleaner. Inside the air cleaner is a metal mesh filter to keep anything big from being sucked through the old road draft hole and also acts as a flame arrestor. The oil filler tube has a sealed cap and there is a 3/8 inch line from this filler tube to the oriface on the rear of the front carb. I do not believe there is a valve in this orifice to leak or stick. It is just a fixed diameter hole for vacuum. This system pulls clean air through the air filter to the rear of the engine, across the lifter valley and up through the oil filler tube, out of this tube into the rear of the carb and is reburned. If this is not how it works, I have been wrong for years. But it will not be the first thing I have been wrong about thats for sure. If I am wrong will someone please explain the actual way it works?
I do not believe a PCV valve will work efficiently on an open system (road draft) since you would have the air from the PCV portion of the system pulling unfiltered
dirty air up through the road draft tube, especially at at an idle. The shape at the end of the road draft tube at the end beneath the car is supposed to create a vacuum only while the car is moving. I would think you should use one or the other and not try to combine both.

Poocho

[jim_ss409]

I know that crankcase pressure causes horsepower losses, that's the reason racers use things like vacuum pumps, exhaust evacuator systems, and large breathers. I'd guess that the pcv system would cease to opperate at wide open throttle because there would be little or no vacuum. So I'd think at full throttle the system would work backwards blowing the pressure back out of filler tube and through the vented oil filler cap or the hose that goes to the air filter housing. I once had a car that would blow the oil cap off if you ran it hard. I looked at the cap on my 409 and I noticed that it only had two little holes ( about 3/8" ) that it actually breathed out of so I used a different cap that had a much bigger hole. Maybe the cap with the small holes would have been fine but I figured anything I could do to reduce crankcase pressure would be a good thing. :dunno I'd guess that the road draft tube system would have less crankcase pressure than the pcv system.

[Ronnie Russell]

jim , common sense--- I just love common sense!!!

[oldskydog]

Put in an air-oil separator like we use on airplane engines. I is a cannister about the size of an oil filter with a sort of screen mesh baffle inside. Any oil or crap coming from the crankcase is collected in the can and only vapor goes out.

[mpris]

Jim, a system with a closed PCV would not have a vented fill tube cap. Prior to 1964 I believe an open PCV system was used. Cheverolet went to the closed system in 64. In the system the fill tube cap is air tight and any pressure would take the same route as with full vacuum. That is, up the filler tube and out the hose to the back of the carburetor. At the point where the vacuum through the PCV valve is insufficient to create a clean air flow down through the air cleaner, the positive pressure in the system also forces the fumes up through the hose connected to the air cleaner into the top of the carburetor to be reburned. In either case the fumes would be reburned and nothing would be expelled into the air. The only problem I could see when this happens might be a little smoke out of the exhaust under high acceleration if the engine were blowing by a lot of oil. The secret to a properly working PCV system is for all the parts of it and the engine to be properly sealed. (No leaks around the PCV valve, no leaking valve cover gaskets, rear main seals, etc.) I think most all of the 64 409s came with the closed system and I never hear anyone complaining about them. I know mine has never given me any problems and it was raced quite a bit in 64-65.

Poocho

[29Coupe348]

well. what im gonna do for the rest of this season is, run a road draft tube, and run a hose out the rear of my car, and let the people behind me worry about it.

[Ronnie Russell]

29,, What ventillation system did your 348 leave the factory with? Whatever that system is ,,,,use it. It worked then, why wont it work today? If you throw oil out the back with the proper system, then your rings are worn out,,replace motor. Mpris,, Nodoubt your pcv system works great. It works exactly as the Federal Emissions Control Board demanded , to allow waste matter a route from crankcase to the intake system of the engine and into the combustion chamber to be burned and exited out the tailpipes. It works great!!! However, I am confused about the "clean air" you describe going in the rear of the engine , across the lifter valley and exiting out the filler tube hose and into the carb. Where does this clean air come from? The only clean or fresh air I know of is the air going into air cleaner , through the air filter and into carbs. How does clean air get under the intake manifold? The crankshaft spinning causes turbulance , and oil sling, along with crank impingeing at some times with oil causing a positive pressure in the crankcase.This pressure seeks the path of least resistance and will rise to seek a way out. Carb. openings have a negative pressure due to pistons intake stroke. Waste matter travels through rear vetillation tube from rear of intake manifold to base of air cleaner where it is sucked through filter into carbs to be burned in combustion chambers. Ventillation is aided by hose from oil filler tube nipple via hose to rear of front carb. Again, waste matter is sucked into carb base and into combustion chambers. System works great, exactly as it was designed. If I could clear up the mystery of the clean air moving across the lifter valley, then I would have a better understanding of the system .. Thanks for your time

[mpris]

Ronnie, the clean air comes into the air filter. It passes through the air filter and goes into and through the flame arrestor, which is inside the air cleaner. It then goes through the hose which is connected beneath the air cleaner to this pipe which is connected to the rear of the engine where the old road vent used to be. There is a vacuum on this line which is created by the system being closed and the oil filler pipe sealed and connected to the rear of the carburetor.
You can test this by removing the big rubber hose at the bottom of the air cleaner while the engine is running. There should be 2-3 inches of vacuum on this hose. This is what creates the continuous flow of clean air through the engine. This supposedly has a two fold benefit. It removes the blowby from the combustion process and reburns it and allows clean dry air into the engine to remove any moisture which may be present. In a normal engine, 70% of the blowby gases are made up of unburned fuel from the combustion process. So not a whole lot of the reburned material is oil.
The only time the blowby gases are brought back up through the rear of the engine and into the air cleaner is under extreme acceleration. This is the only time the vacuum at the base of the carb can be weak enough to be overcome by the crankcase pressure which may force the blowby back up through the rear of the engine into the air cleaner to be reburned. The closed system was designed to do exactly that under high loads.

Poocho

[Ronnie Russell]

Mpris, I asked for an explaination and that is exactly what I got. I wanted to learn and now I have learned, thanks to you. I would have not thought that there would be a negative source at that hose. With all due respect, I do believe the matter that is reburned is not as clean as you make it sound. There is much going on in the crankcase other than minimal blowby. That would be why many experience oily gunk near the road draft tube area. With the enclosed sealed system this does in fact burn that substance instead of spewing it. As I said earlier, the system works and works good, however I have not changed my mind as to what I wish going into my own combustion chambers. Those who are happy with their pcv systems, I am happy for them. I am also happy I do not use them. But again, thank you for your response, as I am always eager to learn.

[Bungy]

I too never would have thought that there would be a vacuum at that end of the hose. However that hose is connected to the air cleaner when the engine is running. Remove the hose at the other end and how much vacuum would you have? I would think it would be much higher then 2-3 inches therefore sucking the gases out of the lifter valley and not putting clean air in. :dunno

[Bungy]

Disregard that last post. After rereading mpris' post and scratching my head a few more times it now makes sense to me. The vacuum is created by the carb sucking out of the oil fill tube in the front. I'll admit it takes me a little while but I eventually catch on. :doh

[64ss409]

mpris did a good job of describing the closed positive system on the 64/65's. There is no"pcv valve", instead there is a .100 orfice at the base of the carb. I am unable to repost the pic even though I renamed it, so here is a link to the picture. (hope this works)
http://www.348-409.com/forum/attachment.php?attachmentid=696
Ron

[gearhead409]

i might be wrong on the 64s but i always thought the 63 and 64s used a pcv valve made by ac spark plug. it's number is type cv 590. it has a valve in it and works like a late model pcv does on todays cars.

[mpris]

Gearhead, you are right about the PCV valve part number. However that part number (AC-CV-590) was only used on the 283 and 327 engines. All the 409 engines used a fixed metered orifice in the rear of the carburetor.

Poocho

[gearhead409]

i don't have a complete 64 engine but the two QB 63 and the two 65 complete truck engines i have has this valve on them. my GM parts book also states this valve was to be used on all 63-64 8 cyl. engines.

[SS425HP]

On my 425 horse 63, there is a 90 degree fitting from the rear of the front carb with the PCV valve screwed into it, then a hose to the rear of the intake, where there is a 90 degree bent tube that fits into the rubber bushing that is where the old draft tube used to bolt on. On the oil filler tube, there is about a 3/8" tube sticking out the side, that has a hose that goes to the air breather. The cap on the oil filler has a seal in it. That's how the closed system was on the 63 425 engines. The 64 had a bigger hose from the oil filler to the air cleaner. Think it was 1/2".
At least that's the way it is now, and that's the way I remember them being set up.

Fred

[gearhead409]

the way you explaned your 63 pvc system is exactly the way it is on my 63 engines except the valve is on the rear carb. 64 engines use a larger air cleaner hose as you have said and the system works in the reverse direction to the 63 engine.

[Ronnie Russell]

They both "SUCK" Sorry guys, I couldnt resist. I am referring to ---both vetillate with vacuum.

[SS425HP]

Gearhead, you are right. The PCV valve is on the rear carb, and the line for the vacuum advance is on the rear of the front carb.

Ronnie, I'm not saying it's a good system. I guess the idea was sound at the time, and it works on a good, tight engine. The more blow by you have, the more junk goes through the motor, which is not good.

Fred

[gearhead409]

i've been reading these threads for several days now. the key to 29coupe348 problem is as Fred said " good tight engine". 29coupe348 has said in an earlier thread that his engine was getting "real tired", you can only put so many band-aids on a blowby problem. he needs to rebuild that 348 this winter and then either crankcase system will work fine.

[Ronnie Russell]

good, sound, logical advice from gearhead. I wish 29 success ,, his car deserves to run as good as it looks.

[mpris]

Gearhead, you may be right about the 63 and/or 65, but according to the 1964 shop manual, the 64 409s used a fixed orifice. See attachment.

Poocho

[bobs409]

I have the 63 shop manual open and it lists AC CV-590 for the pcv valve for 283 thru the 425hp 409 for '63. Looks like '64 was changed as Poocho shown.

I don't have a '65 manual yet so not sure on that year.

[CHEV601234]

The '64s received the PCV (CV-590C) in 49 states. California cars were required to have the CCV system (Closed Crankcase Ventilation). That was the one with the sealed cap on the filler and the metered orifice fitting in back. The CCV was also optional in the other 49.

[gearhead409]

your right i'am right. ain't this website great! we all have learned something here, thanks.

[W Head]

A number of years ago, there was a drag racer in Austin, Texas who used PVC valves to go quicker. He ran 2 PVCs in each valve cover with no PVC baffels in the covers. He ran 2-4s with 1 inch carb spacers and plumbed 2 PVCs to the front carb spacer and 2 into the rear carb spacer. Ran a 8 qt. oil pan with 80 wt. oil, put in 7 qts. of oil and one qt. of nitro. This mixture was sucked into the combustion chamber. He said it was good for a 1/10 off his normal time. He was turning the engine about 8500, so there was a lot of oil mist in the valve covers. I only saw the car run once and moved from Austin. The car really hauled the mail. I heard he finally got caught. I really do not know if this really worked or not, but he thought it did. If I tried this the nitro would have blew up in the oil pan. :doh

By the way,on both my 348 and 409 I have PVCs installed. Used the rear manifold vent and PVCs for a 340 Hp 409, and have a filtered oil filler vent cap. 348-the PVC is on center carb. and 409-PVC is on rear carb. Both work great, but both are new emgines. I just did not like the road draft tube.

W Head

59 El Camino 348-3,2s
59 Impala 409-2,4s

[Ronnie Russell]

W Head, thats quite a story. 80 wt. oil and 8500 rpms!!! Sounds like he could have turned 10,000 rpms with 30 wt. oil. You gotta hand it to that guy, he was trying different tecniques and pushing the envelope. Nitro in the oil pan;; thats quite a pcv system. By the way for those who are keeping score, 998 for pcv systems----- 1 against ,, It gets mighty lonely here at the bottom.

[Ronnie Russell]

Oh, I get it. The nitro thinned the 80 wt. I would have liked to see that experiment. Big glass jug--pour in oil--pour in a little nitro--stir it up-- check the viscosity with the stir stick. But you say " he got caught" not " he blew it up" Guess he measured right!!

[SS425HP]

We used to change the oil because it got diluted with Nitro!!!!!!!!! It won't burn in the pan, but kick a rod out, and you have BIG FIRE. We used to warm up, and make one pass on an oil change. Then change the oil, and make 2 passes. Never more. I don't think nitro lubricates very well. Also, if much nitro was going into the combustion chambers with that set up, you would need to be way richer on the jetting. Has to be something for the nitro to burn, or it will find something. Generally aluminum. Like pistons. I'd say he was lucky he got caught. Then again, at WOT, where is the vacuum to pull the nitro vapors into the intake?
Had a friend in the early 60s, that thought ether was the trick. He bought a box of ether pellets, and dropped some of them in the tank. Swore it ran better. After about a dozen, the car kept quitting. Finally had to take the tank off his 58 to get the pellets out. He had never opened them. They don't dissolve. Didn't do a thing for the car, but he swore it ran better.

Fred

[W Head]

We used to change the oil because it got diluted with Nitro!!!!!!!!! It won't burn in the pan, but kick a rod out, and you have BIG FIRE. We used to warm up, and make one pass on an oil change. Then change the oil, and make 2 passes. Never more. I don't think nitro lubricates very well. Also, if much nitro was going into the combustion chambers with that set up, you would need to be way richer on the jetting. Has to be something for the nitro to burn, or it will find something. Generally aluminum. Like pistons. I'd say he was lucky he got caught. Then again, at WOT, where is the vacuum to pull the nitro vapors into the intake?
Had a friend in the early 60s, that thought ether was the trick. He bought a box of ether pellets, and dropped some of them in the tank. Swore it ran better. After about a dozen, the car kept quitting. Finally had to take the tank off his 58 to get the pellets out. He had never opened them. They don't dissolve. Didn't do a thing for the car, but he swore it ran better.

Fred

I had a friend that used liquid ether in his gas tank and swore it ran better. I thought his exhaust just smelled bad. :stooges
With the PVCs plumbed below the carb. I would think there would be lots of vacuum at WOT

W Head

59 El Camino 348-3,2s
59 Impala 409-2,4s

[MRHP]

No vacuum at wot. Or at least next to nothing on a properly running engine.

[models916]

I have never run a PCV on any of my hot rods. I don't see the point if you change oil often. (I do) I don't see the differnece to the envoronment if a worn out engine spews raw oil fumes out the breather or burns them and produces hydrocarbons. Gas and air is all I want in my combustion chanber. I vote no PCV. Thank You.

[W Head]

No vacuum at wot. Or at least next to nothing on a properly running engine.

You are 100% correct, there is no intake manifold vacuum at WOT :bow , but there is a lot of "suck" under the carbs when you put the peddle to the metal. As I am sure you are aware, that suck is how the venturi clusters work on a carb.

W Head
59 El Camino 348-3,2s
59 Impala 409-2,4s

[mpris]

models916, Hydrocarbons are produced by the release of unburned or partially burned fuel or oil. The release of these unburned vapors out through the vent and tail pipes produces hydrocarbons. The recirculation of these vapors through the engine and repeated combustion cycles via a PCV system is what reduces the Hydrocarbons released into the air. The complete burning of fossil fuels does not produce Hydrocarbons. It is the incomplete burning of these fuels which produces the Hydrocarbons.If the combustion process in the automotive engine were 100% efficient, there would be no Hydrocarbon release out the tail pipes. So yes, the use of a PCV system significantly reduces the release of Hydrocarbs into the atmosphere. As stated previously, the vapors which are reburned via the PCV system usually consist of approximately 70% unburned fuel.

Poocho

[models916]

Hydrocarbons comming out the draft tube? I don't know enough about this to second guess you.

[Ronnie Russell]

mpris, I have acknowledged several times that the pcv system does the job it was designed to do, no argument here. If I accept your figure of 70% unburned fuel ( and I have no reason to doubt it ) , then I must assume the balance , 30%, is oil , or an oil by-product. And how flammable is the " unburned or partially burned fuel " the second time around? Just more food for thought.

[mpris]

Ronnie, you are right. I am sure that the reburning of these vapors reduces the power output of the engine. How much, I don't know. The percentage of the vapors in the intake charge is probably very small and IF only 30% is oil or whatever, who knows what effect it really has.

Poocho

[29Coupe348]

****UPDATE****...I put the road draft tube back on, and went out to a cruise tonight, took it on the highway, about 3000 rpm, no oil at all, none out of the breather, and none even out of the road draft tube...as silly as it may sound, i even felt alittle more power....thanks for all the help. mike

[Bam59]

i like a good ending

[MRHP]

Actually not suck under the carbs, but atmospheric pressure rushing into the engine. Yes I know it is splitting hairs but we don't need to confuse anyone. :cheers

[models916]

http://www.leeric.lsu.edu/bgbb/7/ecep/auto/n/n.htm

I says the PCV works only at full throtle when there is no vaccum. Check it out.

[Mr Goodwrench]

I think thats a bunch of gobely gook written by someone trying to oversimplify a device that been used with sucsess for 40 plus years. :rofl

[Ronnie Russell]

Right when I think I have a handle on this subject, something else pops up. What started my suspicion on this device was that many years ago, I pulled a pcv valve out of a small block valve cover and placed my thumb over the valve. Engine speed dropped and smoothed out. My simple mind told me that this is just a good old fasioned vacuum leak. Valve must be bad. Bought a new one--same result. I dont like vacuum leaks, so I did away with pcv system and never used another. I think we have discussed intake of unburned gasses enough so no sense getting into that. I know it is ironic and even funny that I even care, taken my opinion of the system, but I enjoy knowing how mechanical devices work, even if I dont use it. Mr Goodwrench it seems that the explaination posted by models916 would be easy to check out with a common vacuum gauge. I would volunteer to do such a test ,,,but I dont have a pcv system to run a check on. Looking forward to more information our members may discover.

[mpris]

models916, the example given in the article you mention is vaguely correct. If the PCV valve is the spring loaded type, the opening in the valve in inversely proportional to the amount of vacuum. This is done to keep from upsetting the idle mixture by pulling a large amount of vapors and air into the idle mixture at low RPM (stalling and rough idle) and at idle there is very little blowby to be recirculated. As a load is applied to the engine, the vacuum becomes less and allows the valve to open and allow more vapors and air into the intake charge. Of course as the RPMs increase this introduction of vapor and air will have less effect on the performance of the engine. At WOT, there is very little vacuum through the PCV valve even though it is wide open. This is also the time when there is the most blowby. This is the reason that all cars now use a closed PCV system. In the old open system at the time that the crankcase pressure became greater than the vacuum through the PCV system (heavy load, high RPM), the engine vapors were forced out at the point at which the clean air normally entered the PCV system (oil fill tube or breather on valve cover) into the atmosphere. With the closed system now being used, at the time of low vacuum and high crankcase pressure the gases are forced backward up into the air breather through the fresh air line and reburned.
Some systems do not use a spring loaded PCV valve, but just a plunger which when you shake you can hear it rattle. This plunger is mainly used to prevent a backfire causing an explosion in the engine. Also on some of the new cars and trucks, the automobile manufacturers have gone back to a fixed orifice PCV valve, which is sized for the particular engine (just as the 64 409 had). This means at idle the PCV is working at its maximum rate and as the load increases, the vaccum flow through the fixed orifice PCV valve decreases.
In the article you mentioned, I believe they were just trying to simplify the system.

Poocho

[rogersimpala]

boy now im not sure what all i have just read :confused:
everyone has me confussed now to run a pcv or not :dunno :dunno
I think I know the solution
LETS ALL GO GET A BEER :cheers :cheers :cheers

[Ronnie Russell]

10 -4 on the beer, Roger I am ----POSITIVE--- we have researched the ---CRANKCASE--- and ----VENTILLATED--- the opinions of many.

[29Coupe348]

ok, i just got back from a 100 mile round trip to a show, zero oil...i will never use a pcv again in my rod.

[JimKwiatkowski]

29,maybe you don't need a new short block either :dunno

[29Coupe348]

no, i may not, but i want one.

[dq409]

Ditto Ray !!!:clap Thats the next setup I`m going to after new headers !!!
May even add some stylin` valve cover breathers to my Moon covers !!:eek:

Coupe, I had a similar problem with oil spurting out the filler tube/breather cap.
replaced it with a name brand Hipro cap and fixed the problem.
I`m also using a PCV system,,,dq

[johnnyrod]

I never installed the can under the intake you know the one that goes to the road draft tube. Is this a problem or more to the point whats it do. I am running pcv and am considering the tube instead. Thanks John

[oldskydog]

The can acts is an air-oil separator keeping the oil in the valley and letting the vapor out the tube.

[Mr Goodwrench]

actually w's didnt use a can like the smallblocks, just a baffle riveted too the bottom of the intake.

[dq409]

sheesh !!??? I don`t know how i missed all the pages to this thread !!!!
I posted a reply to ray about the pan-vac system way back there !!:doh

I just read all the posts on this subject and now trying to digest all the info and flak-back.

29,,, I think your problem was/is caused by too much internal pressure . One way or another I don`t think the PCV system is/was enough to cure the problem but with the larger opening/tube of the road tube that pressure now has somewhere to vacate the engine at the rate needed.

Have you taken a compression or leak down test ?

I would be curious to see those results,,,,:deal ,,,dq

[29Coupe348]

sheesh !!??? I don`t know how i missed all the pages to this thread !!!!
I posted a reply to ray about the pan-vac system way back there !!:doh

I just read all the posts on this subject and now trying to digest all the info and flak-back.

29,,, I think your problem was/is caused by too much internal pressure . One way or another I don`t think the PCV system is/was enough to cure the problem but with the larger opening/tube of the road tube that pressure now has somewhere to vacate the engine at the rate needed.

Have you taken a compression or leak down test ?

I would be curious to see those results,,,,:deal ,,,dq
last time i took a compression test it was between 120 and 135 in all cylinders, but the motor is torn down now, getting a freshening up.