PCV or Breather

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wazoo64

wazoo64

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Just got my engine back from the builder and he dynoed without the PCV hooked up to the back of the carb. He says no need to have this it only hinders performance so I bought another breather cap. Should I expect an issues here or is this some good advice.
 
when i bought my dart it had two oil breathers its a street/strip car. (one breather on each valve cover) i never ran into any issues.

I put a set of DC valve covers on it because i was told "street cars" need a pcv. The car still feels the same, i didnt notice any differences
 
If you start seeing oil around the top of the dip stick or your oil seems to get dirty looking quickly then you need a healthy PVC system. I personally wouldn't run my motor without one unless it was a drag only motor.
 
hi, horsepucky, they don't cause leaks!!! if the ring seal is good. no leaks.
have a 340 stocker, with over 300 runs, and l.t. rings, no leaks!!!! can run it with breathers.
 
PCV is usually for street cars to prevent the buildup of blow by gas in the oil during normal use. Drag cars and street machines presumably have the oil changed more frequently so it probably wouldn't matter. It's really to get fresh air in and to prevent sludge. Leaks result from clogged oil passages.

How do you drive the car? How often do you change the oil?
 
My daily driver will always have one and the ones out on the farm and getting 3 to 4k miles,
Race car's dirt oval to drag strip get there oil changed after almost every event.



Just me.:drinkers:
 
OK, here's my take on this:

At WOT the vacuum in the intake manifold is (or should not be) more than 1.5" and the PCV valve is closed anyway. The PCV really is doing it's job at idle and steady state cruise by evacuating the crankcase of water vapor from condensation/combustion as well as unburnt fuel and whatever blow-by gets past the rings. No engine has a 100% seal (0% leakdown). The lighter distillates in oil will also tend to evaporate and mix with water and fuel then solidify on the inside of the valvecover, rockers, etc causing problems down the road. When I lived out east, I saw enough condensate in the engine oil to almost look as though it had a head gasket leak. Pull the VC's, clean them ip, and change out the PCV and poof, problem solved. That water plays havoc on your longblock causing sludge and oil delivery problems which as mentioned before, can cause leaks and other nasty stuff. :)

Back in the day their was no PCV system, just a so called "Draft Tube" that hung under the car and evacted under speed. So in a nutshell. here's my response:

Q: Do I have to have a PCV system on my street/strip driven car?
A: NO, but your engine will last longer

Q: Will a PCV make my car faster?
A: NO, but it won't slow it up any appreciable amount either. Depending on the state of tune of the engine, you may have to make jet/idle mixture changes if changing to a PCV or open breather but most likley not.

Strip only cars should have a header evac system as that is the only type that positively evacs under WOT and may reduce windage but that's debatable. Some guys run vacuum pumps with great results over 5 or 6k rpm.

Circle track cars run open evacs because as Memike says, the oil is changed every race and it's just one more thing that won't break causing a lost race.

I hope this is the type of response you were looking for.

Now, back to work bleeding my brakes.

Joe
 
ramcharger said:
OK, here's my take on this:

At WOT the vacuum in the intake manifold is (or should not be) more than 1.5" and the PCV valve is closed anyway. The PCV really is doing it's job at idle and steady state cruise by evacuating the crankcase of water vapor from condensation/combustion as well as unburnt fuel and whatever blow-by gets past the rings. No engine has a 100% seal (0% leakdown). The lighter distillates in oil will also tend to evaporate and mix with water and fuel then solidify on the inside of the valvecover, rockers, etc causing problems down the road. When I lived out east, I saw enough condensate in the engine oil to almost look as though it had a head gasket leak. Pull the VC's, clean them ip, and change out the PCV and poof, problem solved. That water plays havoc on your longblock causing sludge and oil delivery problems which as mentioned before, can cause leaks and other nasty stuff. :)

Back in the day their was no PCV system, just a so called "Draft Tube" that hung under the car and evacted under speed. So in a nutshell. here's my response:

Q: Do I have to have a PCV system on my street/strip driven car?
A: NO, but your engine will last longer

Q: Will a PCV make my car faster?
A: NO, but it won't slow it up any appreciable amount either. Depending on the state of tune of the engine, you may have to make jet/idle mixture changes if changing to a PCV or open breather but most likley not.

Strip only cars should have a header evac system as that is the only type that positively evacs under WOT and may reduce windage but that's debatable. Some guys run vacuum pumps with great results over 5 or 6k rpm.

Circle track cars run open evacs because as Memike says, the oil is changed every race and it's just one more thing that won't break causing a lost race.

I hope this is the type of response you were looking for.

Now, back to work bleeding my brakes.

Joe
Click to expand...

Great explanation Joe. Now get them brakes bled.:toothy10:
 
Lol! Done, but it's long story, don't want to steal the thread. Why hasn't fwaugh responded?
 
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