Venting crankcase to headers- anybody doing it? Thoughts?

It's getting time to figure out a route for my crankcase venting. I'll be running four deuces with no real clean way to plumb a PCV intake into the carbies or manifold so I'm looking at pulling the pressure from the original PCV vent (without the pcv valve) at the rear of the Chevy 348 down to a one way valve plumbed into a header collector. Pipe welded into collector would be baloney sliced at 45 degrees. I'd use the original vented oil cap on the fill tube to draw in fresh air.
Exhaust is custom 1 7/8" headers with gl*** pacs exiting at rear of running boards. Anybody done this or have any thoughts?

Terry

 

I am not sure how well this would work on a street car. I think if you are going to try to do this, you will want to get the breather tube as close to the exh ports as possible to make sure you burn off as much oil mist as possible.

 

Terry, your method is very similar to what we used on a drag car back in the 70's, it did a good job of providing neg pressure in the pan to eliminate oil getting past the rings.
...have never tried on a street car though....

 

If you don't run enough rpm to create a negative preasure you might put raw exhaust back, Only my though!

 

i've seen that used on several types of cars with success....even 4 cylinder vw's...should work, may smoke a little bit may not...i think there is a certain spot that is better to place it to get the most out of the exhaust pulses and stuff, but i cant remember

 

i ran the pan o vacs on my bbc anglia......it would smoke pretty good ...heard that my stud girdles may have been part of the cause.....

 

I don't see how it could work with any kind of back pressure in the exhaust (full length pipes and/or mufflers).
Larry T

 

will work make sure pipe fitting sticks in the header about 1 inch.weld pipe in header at 45 degree angle from front. cut pipe in header at 45 also so exh. flows smooth.

 

It would work some, probably dosn't need much, but you will want to watch your oil. On drag cars we use them but most engines restrict the oil going to the top end and the evac releaves the pressure, with a street engine the oil must be at full volume to cool the springs etcetc and a good mist of it will be pulled out the header tube and you will need to replace it. Just a thought.

 

V8's advice on installation is straight from Mr Gasket and Not correct. Not to offend V8 but the tube need to be cut at about 45deg, inserted into the collector and welded so the the open 'slash' faces away from the exhaust source and creates low pressure for the breather. Imagine riding in your dads 64 impala and you open the vent window a crack. It protrudes into the airstream and creates negative pressure inside the car and your dads cigar smoke gets ****ed out the window. So no, please don't cut the pipe for smooth air flo. And you can cuss me V8, but not your fault as were misled yourself and had best of intentions.

 

OJ is correct. I have done this a few time s and most recent;y on y blown flathead....works very well on a 2" straight thru exhaust with straight thru mufflers.

Crankcase fumes get ****ed out of the valley and put thru the exhaust. I have disconnected the hose from the header's collector and there IS vac***/suction, even at lower rpm.

Rat

 

We've found at my work ( race engine shop) that the GM (smog A.I.R.) one way valves take the heat and last longer than the ones that come in most kits.
I'll get the part number Monday and post it for you.
Smokey

 

It won't work with any downstream backpressure - only with open collector - as mentioned previously. I have done dyno tests on similar systems and could only get positive pressure at the probe with a full exhaust system

 

Could you do a draft tube setup? My '66 F100 had one stock. Not the greatest thing at idle, but might work OK at highway speeds. Just a thought......

 

I had planned on installing the pipe at a 45 degree angle with a 45 degree slice so that the exhaust gases would p*** over the end of the slice and lower the pressure in the extractor pipe. My decision was based on Bernoulli's Principle. This principle states that as the speed of a fluid over a surface increases, the pressure on the surface decreases. As the exhaust gas speed past the end of the tube extending into the collector increases, the pressure at the end of the tube decreases allowing g***es to be pulled from the crankcase.
How are you guys who report success on the street positioning the pipe?

Terry

 

the kits come with one way valves...

 

First used the Morosso evactuation system in the early 70's in my SS/IA Camaro. It worked great and helped in conjunction with the TotalSeal rings. I gained a little more than 1/10sec in the quarter.
A Couple of things that must be followed, the baffle must be under the tube in the valve cover, and the engine must be sealed up real good. Any vacuum leak at the valve covers, valley, timing cover or pan.
This link also has instructions for placement of the 45 degree tube, and this needs to be done like OJ (and the Moroso instructions say) or this won't work worth a hill of beans.
I have never tried this will a full exhaust, but as long as you exhaust system is designed correctly (meaning it is really scavanging) it should work. IMHO

Picture of the SS/IA Camaro during build;



http://www.moroso.com/catalog/categorydisplay.asp?catcode=13023

 

More of a question than anything else. If you start with back pressure in the pipe, you're gonna have to have vacuum at the end of the tube to pull anything out of the engine(unless the engine is operating under more pressure than the pipes), not just reduced pressure. Does it work this way or is there still pressure (even reduced) at the tube.
Larry T