Valve Cover Holes - yes or no?

fasttback · Oct 10, 2006

I bought some Motorsport tall valve covers and they do not have breather holes, but can be drilled. Originally my car had breathers.

I'm for the breathers because of the ability to relieve and reuse blow by gases depending on configuration.

My question - what ventilation setup would be best for a modified sbf:

Breathers open to the atmosphere,

Breathers hooked up to engine vacuum (via pcv valve), or

nothing at all?

66Runt · Oct 10, 2006

For a carbureted, naturally aspirated engine in good condition

I'd run one PCV from one valve cover to the plenum chamber. The other valve cover would have a hose to the base of the air cleaner inside the filter.

brianj5600 · Oct 10, 2006

I run mine open on both sides. Oil in the cyclinder can cause detonation, so no pcv for me. I think pcv is an emmissions thing. I have never seen one on a racecar.

iskwezm · Oct 10, 2006

brianj5600 said:
I run mine open on both sides. Oil in the cyclinder can cause detonation, so no pcv for me. I think pcv is an emmissions thing. I have never seen one on a racecar.

same with mine

BullittStangV8 · Oct 10, 2006

I ran open breathers that were open to the atmosphere.

65ShelbyClone · Oct 10, 2006

brianj5600 said:
I think pcv is an emmissions thing.

That is the ONLY reason anyone ever used a PCV system. The Motorsport valvecovers without filler/breather holes are usually for 5.0s that have the crankcase vent on the back of the intake.

67Dylan · Oct 11, 2006

brianj5600 said:
I run mine open on both sides. Oil in the cyclinder can cause detonation, so no pcv for me. I think pcv is an emmissions thing. I have never seen one on a racecar.

iskwezm said:

same with mine

Click to expand...

Yeah, me too.

stirling33 · Oct 11, 2006

brianj5600 said:
I run mine open on both sides. Oil in the cyclinder can cause detonation, so no pcv for me. I think pcv is an emmissions thing. I have never seen one on a racecar.

To the guys who are saying they are running them open, do you just mean that you have breather caps on both sides and no pcv hook up?

Max Power · Oct 11, 2006

I am running my PCV because I don't want oil film from the gasses on my valves covers all the time. I prefer my blowby burned rather than dumped on my clean engine.

65ShelbyClone · Oct 11, 2006

I'm tempted to make a catch can setup for mine so I don't get the oil film, yet keep the open ventilation. I have some chrome parts store breathers and extensions. I still get some oil, but the extensions helped.

Max Power · Oct 11, 2006

Before I built my motor, it used to have a lot of blowby. I fashioned a fitting with a gas filter that stuch straight up into the air. The oil would catch in the filter and drain back in to the engine, and the cleaner gasses could escape. It wasn't pretty, but it worked really well. I stole the idea from a car at the drag strip.

iskwezm · Oct 11, 2006

i dont have any film on my covers

Max Power · Oct 11, 2006

Then apparantly you have no blowby.

krash kendall · Oct 11, 2006

He also has a brand new motor...lucky guy!

brianj5600 · Oct 11, 2006

Open as in a filter in each valve cover. Mine are oily thanks to big ring endgaps. That is needed because someday I'll have a turbo, but now it is a nitrous kit.

65ShelbyClone · Oct 11, 2006

iskwezm said:
i dont have any film on my covers

Are your covers baffled?

I have a 10k mile engine and still get the film somewhat, but my covers aren't baffled and neither are the breather extensions. I have some stainless potscrubbers I was going to stick in there, though.

66Runt · Oct 11, 2006

Good description and reason for having a PCV valve

The PCV Valve, or Positive Crankcase Ventilation valve is an emission control device that routes unburned crankcase blowby gases back into the intake manifold where they can be reburned. The PCV system is one of the oldest emission control devices, and also one of the most beneficial. Besides totally eliminating crankcase emissions as a source of air pollution, the constant recirculation of air through the crankcase helps remove moisture which otherwise would cause sludge to form. Thus the PCV valve extends the life of the oil and engine. The PCV valve requires little maintenance. The valve and filter should be replaced somewhere around 30,000 to 50,000 miles(see the vehicle owners manual for service intervals).

Taken from this site:
http://www.faqfarm.com/Q/What_is_a_PCV_valve

Of course you need to actually drive your car more than 8 miles at a time to truly see the benefits

iskwezm · Oct 11, 2006

krash kendall said:
He also has a brand new motor...lucky guy!

its NOT brand new, I have about 800 miles on it

iskwezm · Oct 11, 2006

double post

67Dylan · Oct 11, 2006

65ShelbyClone said:
I have a 10k mile engine and still get the film somewhat, but my covers aren't baffled and neither are the breather extensions. I have some stainless potscrubbers I was going to stick in there, though.

A few cars ago (EFI) I had problems w/oil out the breathers and problems w/the pvc. I replaced non baffled covers for baffled ones, added the pot scrubbers, replaced the pvc, & added a fuel filter in line to keep an eye on an oil being sucked back thru. No oil no problem.

Valve Cover Holes - yes or no?

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