PCV or not

Dirtracer 619

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Ok so I ask a lot of questions it's just because I need to know things so I don't make more mistakes than I already have. So I had to rebuild my motor and have added a new fuel injection system so hoping to bring reliability to the table.

So on to my question. Run a PVC or are two large breathers one on each valve cover enough. Some say you will blow out gaskets without a PCV. Others say you don't need it. I don't like connecting valve covers to the throttle body I guess I could run a catch can.

So what do you guys think. Advice is always appreciated
 

Dirtracer 619

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Fresh never ran rebuild, new sequential fuel injection
 

jon coleman

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ive heard good things about the header scavenging set up, weld into header venturies bungs that create vacuum, hose goes up to valve cover , drag racers luv em'.a true ' pvc' set up is pulling air Thru eng. to remove moisture& blow by gasses, from air filter in one valvecover, thru eng, out other valve cover, thru pvc valve, or an orfice of specific size, to intake man, stock street car i like them
 
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JEFFRPM

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Put a crankcase vacuum pump system on it with a top vented puke tank & breathers on each cover or no pump with breathers on each valve cover & no PCV valve

PCV systems only (barely) work when thiers vaccume supplied to the PCV valve, when thiers no vacuume (pushing the loud pedal) the PCV internal plunger drops from lack of vaccume causing a no or very low air flow making whatever the engine is producing in vapor (blowby) to go out the breather & nothing out the PCV valve CAUSING crankcase pressure = not good.

Take a PCV valve off & blow in it you'll be surprised that you can't very well or at all.
 

jon coleman

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would a smog pump work?, does it need under, or, over drive pullys?, how much hp are they good for??how are they routed?
 

JEFFRPM

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Most of the inexpensive aftermarket ones are made from smog pumps, basically the input side of the pump splits into a "T" one valve cover tube going on each side of the T & the output goes into a catch can with a breather tank/filter mounted above the catchtank for any drainback to the catchtank with drain on the bottom.
Most of them are run @ 60% overdrive @ 5000rpm crank speed if faster you need to slow it down because they get pretty inefficient going any faster plus they come apart internally. These ones don't really pull any vaccume resulting in no HP increase only controlling the blowby

Now for the billit aluminum ones those things run 70 to 80% overdrive with no problem spinning the motor to 8000rpm without any problems still not making any significant HP increase.

I've seen 4 stage gilmore belt drve drysump pumps (without oil supply) used for crankcase evacuation run at those speeds pulling 8 inches of vaccume on the motor they have to help make some kind of power increase but I have no idea how much.
 

Bert is my name

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For a low buck vacuum pump the brake vacuum pump off of a early 90s power stroke pulls a lot of air. I would run it through a catch can.
 

partybarge_pilot

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Vacuum pump can and will suck poop past your seals. They are not set up for vacuum. Great for a drag car, for something that gets dirty not so much.
 

Bert is my name

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For simplicity I think the pan evac kit hooked up to the exhaust is probably the best for an offroad truck. Not much to go wrong there.
 

gwizz

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no matter what a PCV system will suck oil vapor into your air intake stream.

i would just do two large breathers, orrr do blow by or draft tubes that go and vent below the truck.
 

Bert is my name

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The pan evac kit pulls oil vapor into the exhaust. Oil vapor in the intake can cause tuning issues and detonation. Its been my experience that breathers fall out or get loose. They are one more path for dirt to get into the engine.
 

MTPyle

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I don't think you need to return the Crank case vent to Intake or exhaust, thats an Emissions thing not performance.

All you need is a vent from the valve covers to a tank to catch the moisture and or oil. You would be surprised at how much we get in our tanks after one race, even with a new engine.

And you must have a way for the crank case to vent. We had our engine on the dyne and forgot to take off the caps from the valve cover breather fittings. Started the engine and oil was flowing out of the front crank seal. If the pressure does not have somewhere to go it will find a way.

Here is a breather can that we had, you can run both sides of the valve covers to one tank.

Moroso Tank
 

Dirtracer 619

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Yep thats what we did so once racing resumes we can check it. Thanks
 

MTPyle

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haha I didn't look at how old the post was. I forget that these sections get stale.

Mike
 
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