351W crankcase evacuation

[jse9]

I have a 351W that will eventually run a vacuum pump but for the time being I'm just venting into a breather canister. For ventilation points I drilled a hole in the back of the intake manifold, and through my fuel pump block off plate. I'm venting with -10 AN line. The breather tank is about the same height as the carburetor. I plan on using the hole in the back of the manifold when I put my vacuum pump on.

When I started to prelube the engine I started puking oil out of my breather tank. This is presumably from the line coming from the fuel pump block-off. How is oil getting up there? From what I understand, the timing chain and fuel pump arm just get lubricated from oil draining back to the pan, not pressurized oil. Is this oil coming out of the line normal considering it's height is well above the engine? It makes me nervous that I have some sort of blockage prohibiting oil drainback to the sump.

I stole the idea for the ventilation points from Jon Kasse's engine master 460 buildup, he vented from the same areas. He actually just had breathers mounted at each point, wheras I route them to a common tank. Hopefully my assumption that what works on a 460 won't nesessarily work on a 351W, and nothing is wrong. Also, does anyone have any ideas for other venting points closer to the crankcase than the rocker covers?

Thanks!!!

UPDATE
This is actually puking from the line that is connected to the intake manifold. I have it in the very rearmost v- part of the intake. I guess there is a strong stream of oil coming directly underneath it finding it's way into the line. If I disconnect the line and hold it vertically no oil comes out. I think I just need to plumb it closer to the middle of the intake. Right?

[mustangII460]

May I ask what you did all this for?

[jse9]

Just to ventilate from a spot better than the valve covers. Venting directly from the crankcase is better. Since I have no vacuum source right now it will allow it to breath freer than the valve covers would. But I do plan on running the rear to a vacuum pump in the future, and at that time just putting a regular fuel pump blockoff back on.

Like I said, I stole the fuel pump block off idea from Jon Kasse:
http://www.popularhotrodding.com/eng...3/0405phr_emc/

By the way, after I realized that the oil leak was from the back of the manifold and thought about it for a while, I realized that the only way oil could be getting up there was if I left the plug off of a galley. Sure enough I pulled the intake off and forgot the 3/4" plug for the rear galley. Doh!

[88fivepointoh]

From My experience, That is going to cause you to have a moisture biuld up in the motor that will corrode and rust the interals. any open area in a motor will collect moisture and biuld up and transfer into your oil.. I would have left it alone.

[jse9]

Moisture buildup can occur in the lines between the tank and the engine, and end up running back into the engine, but only in the winter. It's not the fact that there's a hole in the engine that causes the moisture buildup, it usually comes in from the lines outside of it (long oil filler necks = bad). As far as venting directly over the crankcase, look at the factory PCV setups on engines that use valley pans (ex. Pontiac), they always vent from there. I don't have to worry about cold temps here in CA so moisture in the lines won't be a problem. The only other moisture sources are not ventilating well enough, or obviously a blow head gasket.

Thanks for the heads up though, if I lived anywhere else in the country I would have done this differently, like routing the lines in a downward fashion so moisture that collected could only run away from the engine.

[88fivepointoh]

What lines are you talking about? unless you have a oil cooler there are no lines. Secondly doesn't matter what climate your in, The temp difference between 180 degree plus motor and at best 90 degrees weather is enough of a gradient that will cause moisture biuld up. what happens to a coke can when it comes out of the fridge or cooler and left outside or on the counter top, moister biulds up outside of the can right? if you have access to fresh oxygen supply ( hole ) you will have condensation. plain and simple. Your motor is even worse at that cause your talking about a 90 degree plus gradient.

Chemistry major... Thanks..

[jse9]

Coke cans are in a cold fridge. The water in the air around the coke can turns to a liquid because at the surface of the coke can, the temperature and pressure in that area put H2O in its liquid state. It is about gradient to an extent, but one of the temps must be cold. When you are done welding on something and rapidly cool it it does not form condenstaion. Look at your water properties table in the back of your engineering friends' thermo book.

In Rochester you would have hot air in your lines between your engine and your vacuum pump exposed to the cold outside air. Whether or not condensation in the lines form (or in the engine) depends on how much the air in the lines cool (approaching the T at the current P where H2O turns to liquid). Since P in this equation is approximately constant between your state and mine it depends solely on T (absolute, not delta).

Mechanical Engineer, thanks

[rwhite65]

I can not say I know a darn thing about this topic. Can not say I have ever seen someone doing it in all honesty. But there are a lot of guys on here, and if it truely helps....wouldn't more people be doing it?
What am I missing here?

Ryan

[jse9]

1. I did not have holes in my rocker covers
2. I've seen many people with vacuum pumps pull from the manifold
3. Jon Kasse did it on his engine masters 460 (gave me the idea for the second breather location)
4. Wanted to do something different.

Plus, the pressure all comes from the crankcase. The closer you get to it the better you can vent. This was a little detail that I chose to do with the engine apart. If everything was together I wouldn't have bothered and I would have just used a rocker cover. I'm not suggesting that venting from the rocker covers is inadequate, it's plenty efficient. But I'll only be using one source when I use the vacuum pump and I wanted a central location closer to the crankcase. The vent from the fuel pump blockoff is only a temporary until I get a vacuum pump. As most of your hot rods are I'm sure, this is a work in progress.

[Stang_ROTY]

I just converted from a PCV EFI Edelbrock lower manifold to a non-PCV lower manifold designed for racing purposes. Therefore, I currently do not have any PCV system whatsoever, but I put a breather cap on my valve cover (pass side), and am still pulling from the vent port on the oil filler tube (same side as breather cap---pass. side) into my TB via a vacuum hose. All I notice is a bit of invisible mist coming from my breather cap....why is what you are attempting to do better than what I'm doing? Am I doing something wrong or is this an experimental design you're trying?


[QUOTE]Originally posted by jse9
[B]Just to ventilate from a spot better than the valve covers. Venting directly from the crankcase is better.

[88fivepointoh]

Originally posted by jse9
Coke cans are in a cold fridge. The water in the air around the coke can turns to a liquid because at the surface of the coke can, the temperature and pressure in that area put H2O in its liquid state. It is about gradient to an extent, but one of the temps must be cold. When you are done welding on something and rapidly cool it it does not form condenstaion. Look at your water properties table in the back of your engineering friends' thermo book.

In Rochester you would have hot air in your lines between your engine and your vacuum pump exposed to the cold outside air. Whether or not condensation in the lines form (or in the engine) depends on how much the air in the lines cool (approaching the T at the current P where H2O turns to liquid). Since P in this equation is approximately constant between your state and mine it depends solely on T (absolute, not delta).

Mechanical Engineer, thanks

ok H20 = WATER... so its liquid no mater what. what your trying to say is put oxygen and hydrogen in its liquid state. now as for lines, what lines are you talking about? What vacuum pump are you talking about? If you weld something, which whatever you weld is 600 degrees plus, its to hot to even sustain condensation, however if you weld something and put it in a cold area and i mean cold it will fpr condensation from the air around it. Either way I think were all confused on what your doing, I wouldn't have drilled any holes in my intake i would use a breather element and suck the vapors out via my intake stream or PCV..

[88fivepointoh]

I checked around with some guys and all we are coming up with is that by doing what your doing your not going to gain anything otyher than angrivation and confusion. also if this is an EFI motor, your going to screw things up entirely from un accurate manifold pressure readings.

[jse9]

88fivepointoh:
"ok H20 = WATER... so its liquid no mater what"

H20, as with many substances can be gas, liquid or solid. Vacuum pumps have lines between the engine and the pump. What is so aggravating about having a line come out of your manifold? Condenstion happens from something being cold enough to turn the H20 in it's gaseous form in air to liquid. It's a finite temp that does this. Note how the air is dryer in the winter. I'm done going back and forth on this.. I appreciate the devils advocate thing but this has been beaten to death....
Also, how you vent your crankcase has no bearing on manifold vacuum and will not change your manifold absolute pressure. Either you explained what I'm doign to your friends wrong, or they don't know what they're talking about. What goes on in the crankcase does not affect manifold vacuum except in extemem cases. The hole I drilled in my manifold goes directly to the crankcase, not to the plenum.


Stang_ROTY:
If you are putting manifold vacuum (from your TB) to your oil filler tube than you effectively have half of a PCV system. Doesn't the oil fill tube go to the air inlet? Then this would be considered venturi vacuum and not manifold vacuum. If it's in front of the throttle blade it's venturi vacuum, if it's behind it is manifold vacuum. The PCV system consists of 2 parts, the manifold vacuum (where the PCV valve is) and the venturi vacuum (air inlet tract, air cleaner base for carbs). When you are idling the manifold vacuum does all of the venting. When you open the throttle manifold vacuum drops so it quits venting. At this point venturi vacuum takes over (pressure drop in the inlet tract due to velocity of air moving through it). This is the same principal as to why air rapidly is drawn out of an airplane (or car) if the window is open. It sounds like you have manifold vacuum going to your oil fill tube and a breather to substitue for the venturi vacuum portion. If this is so, when you are getting into the throttle the breather is essentially the only venting source that you have. There is nothing wrong with that. It's not as effecient as the factory closed system but it works. To figure out if your source is manifold or venture put your finger on the line when the car is idling. It will not be pulling any vacuum at all if it's a venturi source. Some throttle bodies have sources so be careful.

If the line you are talking about is going to venturi vacuum (the air inlet, in front of the throttle blade) then I would get a breather with a hose end on it (like used for the Moroso Pan Evac systems) and run that to manifold vacuum. Get an inline PCV valve to put in the hose. The stock PCV system works great for keeping engines clean. It always draws a vacuum in the crankcase, wheras breathers just allow the pressure to vent. Look for moisture buildup under your valve covers (looks white). If you don't see any then you are ok. I had a system with breathers only once and I ended up going back to a stock type PCV system. Now I have only breathers but it's because I wanted all of the plumbing to be in place when I installed my vacuum pump. As far as me pulling from the intake manifold, it's more normal to pull from the valve cover but I've seen people pull from the manifold and I think it would work better personally.

[88fivepointoh]

well if you have your regular PCV valve installed, with a vacuum punp it will effect your manifold pressure do to the pcv valve being hooked up to the intake... now this is only a worry for an EFI car...

[jse9]

You would never run a PCV valve with a vacuum pump. The entire crankcase will have one opening that goes to the pump and thats it (so it can create a vacuum environment inside the crankcase).
The method you choose to vent your crankcase will have no bearing on Manifold vacuum. You're confusing crankcase pressure and manifold pressure. With a PCV valve you use the manifold to vent the crankcase, but this has no appreciable affect on the MAP. Any other method has no affect on MAP.

[Jeff Chambers]

Crankcase evacuation is a good way to make extra power. By pulling vacuum in the crankcase, you promote better sealing of the rings (creating less blow-by), better oil control (we all know that is better), and stronger signal to the venturis if you're a carb'd car. There's a power gain due to just the differential pressure that the piston sees when the crankcase is evacuated. Imagine that under normal config the top side of the piston sees a combustion chamber pressure of 200 psig and the crankcase is under say 5 psig positive pressure. The net pressure on the top of the piston is 195 psig. Now if you suck 15in-Hg (~7.5 psi vacuum) vacuum on the crankcase you now have a net pressure on the piston of 207.5 psi. That's a difference of 12.5 psi. On a 4" bore piston, that's an extra 157# of force pushing the piston down. When in motion, that's HP.

I run a crankcase evacuation system using the air pump from an F-150, spinning it backwards. I pull from the valve cover and exhaust to a breathered cannister. I pull about 12 in-Hg at 3/4 track when the engine's under its heaviest load. It pays off. On the engine dyno, a good vacuum system can be worth as much as 3-5% extra HP/TQ.

[88fivepointoh]

That sounds good to me... Finally understanding the causes.. Is it really worth the extra hassle though?

[jse9]

Hey Jeff, how long have you run your air pump? I've been considering going with a factory air pump also. Did you get yours modified or are you running it as is? I saw a website who sells modified units for racing but he wants as much as the Moroso pumps for them. I have a hard time paying almost $400 for a factory air pump. Supposedly his mods compensiate for the fact that when operated as a vacuum pump it will see a oily environment and his modifications tailor the internals of the pump to be used in this way.

Have you had to rebuild yours yet? Do you ever drive on the street? Let me know about the mods you made to run it, and if it has any longevity issues that you know of yet.

The place who sells them is:
http://www.gzmotorsports.com/

88:
Definately worth the hassle and money. Especially if you build for it from the beginning using lower tension rings that you would normally run. Net increase is usually in the 20 Hp range but on a dedicated vacuum pump motor it's not unheard of for it to be worth 40hp.

[rwhite65]

Ok, now I have found a topic generally not discussed, but of interest to me. On a carburated car....where and how do u normally want to evacuate it for best power?

For years I have watched guys just plug hoses here or there....now I am wondering if I am losing power somewhere.

Ryan

[jse9]

Vacuum pumps are the best way to go in terms of power. They are very expensive to setup and there are some issues with longevity on the street.

Pan evac systems (valve covers plumbed to headers) work great on open header race cars and nothing else. You may have seen someone run this on the street but rest assured that you had a better system with your stock PCV setup. This system relies on the high velocity exhaust gases exiting the the atmosphere at atmospheric pressure to create a pressure drop at a point tapped into the collector. This does not work if the collector does not exit to atmospheric pressure due to backpressure in the system. Even if you run sewage pipe there's going to be more backpressure than if it were open. The result is the valve in the collector shuts and you have no crankcase ventilation when you most need it (under load). In street cars I've seen this result in oil past the rear main seal.

If I can't run a vacuum pump my second choice would be a stock type PCV system. Many years ago I had a 350 Chevy running open breathers on either valve cover. I started to get white stuff under the valve covers (moisture) and sometimes I saw smoke under load. This prompted me to switch to a stock PCV setup. Either system resulted in 12.50s @ 108 (give or take) at the dragstrip so I can't say that there was an performance difference. My car never smoked again, inside my engine was spotless, and I gained a BIG notice in driveability down low. This was a daily driver though. The buildup probably wouldn't be so bad if the car was driven less.

With a PCV system you use manifold vacuum like you would an accessory, so this cost power, and you contaminate your intake charge. The plus side is that you apply a vacuum to the crankcase, which has been proven to add horsepower (and keep things clean!). The open breather setup doesn't use manifold vacuum so therefor doesn't add any contamination, but you NEVER pull a vacuum on the crankcase. Also, a poorly ventilated crankcase will eventually add contamination to the intake charge so that difference really doesn't come into play. The crankcase is always at a higher pressure than atmospheric (otherwise nothing would vent out). As mentioned above, vacuum on the crankcase adds power. Marginally in the case of a PCV system when compared to the big power a vacuum pump can add, but the effect is the same. The best way to run a PCV system is where you apply manifold vacuum to one valve cover (or where ever you want to vent from, valley pan on some motors), and run the other valve cover to the air cleaner/inlet. This uses the venturi effect of the entering air to pull a vacuum on the crankcase when the manifold vacuum drops, so you always have a vacuum whether your load is low (high manifold vacuum), or your load is high (large amount of air entering, large pressure drop (vacuum) in air inlet). Some people run PCV with a breather which isn't nearly as efficient. It's best to keep the system closed.

I agree, this is an interesting topic that isn't really discussed very often. Leads to alot of confusion about what is really going on for some people. I'd love to see a dyno test running a stock PCV system against an open breather on each valve cover. But I'm sure the .05% difference wouldn't be that interesting to people, and the hot rod magazines aren't in business to tell people to leave their stock stuff alone.