Has not been a problem.

 

If you don't have too much crankcase pressure then a pcv valve isn't needed (except perhaps for emmission reasons)

 

PCV's are neat for most stuff....but if I can avoid it....I definitely will. I prefer to not have the oily residue going into the intact tract. Just gums up things that are best left nice and clean and oil doesn't help octane levels a bit when trying to run pump gas.

We spend a lot of time trying to make sure we have perfectly round cylinders, excellent ring/piston fitting etc to keep blowby to a minimum. If you look at the videos of this engine during the dyno testing you'll see not even a wisp of smoke out of the breathers at 7500 rpm.

http://www.youtube.com/cemagonline


This thing went through more than 35 full throttle pulls that limited RPM to only a 300 RPM per second increase under full load. That is extremely tough on parts and any problems will show up quickly. The breathers you see in the pics are the same ones that were on it during testing and haven't been touched, Still perfectly clean.

My 540 has been together quite a few years and still runs with no PCV. The engine stays nice and dry when cruising around.

Now PCV's DO help keep down any oil fumes and surely help with keeping leaks to a minimum under normal operation, but under WOT when pressure really builds they do nothing at all. If an engine NEEDS a PCV to keep oil leaks down...there are other problems. Either it's got too much blowby even at low speeds or it has gasket issues. Either case, it's a bandaid..not a fix.

JIM

 

Really some people have told me that without it I will blow all the seals out, corrode the engine internals, wreck the oil, loose horsepower and mess up my fuelling.

 

Those people don't have a clue.

PCV works off vacuum or pressure differential if you want to look at it that way. The only time you have any to speak of is at less than WOT. The .5-1.0" at WOT won't make any difference and the PCV closes. At WOT you are dependent on whatever real breather system the motor has.

It is a controlled vacuum leak..so it's one more thing you have to deal with in carburetor tuning. Not a big deal as it leans the mixture,,but it's there.

Corrosion comes from moisture in the oil. If you have that then you aren't getting the oil hot enough to boil it off.

Don't see how a PCV will help oil life. In fact if you get real picky you are actually drawing outside air *through* the crankcase and pulling it into the intake tract and into the cylinders. Better have a much better inlet filter on that PCV system than you have on the the carburetor inlet, because whatever you pull into the crankcase is going right into the oil. What comes through the carb just goes on TOP of the pistons and out the exhaust. The PCV air goes into crankcase first and THEN to the cylinders. Think about this the next time you see an oil cap with the wire mesh in it or just a baffle for the breather. That's fine for pressure exiting..but not good enough for a PCV drawing outside air INTO the motor.

Surely can't see how ingesting nice oil vapors into the intake tract will help HP. In fact..if you are dyno testing and you do get a little drip of oil onto the header and a puff of smoke..you will immediately see it on the dyno HP results. That oil vapor takes up space that should be filled with fuel/air mixture.

And again, if seals are blowing out, no PCV can save that. A PCV has to have a breather/inlet to function under light loads and that same breather setup has to be capable of venting whatever pressure oocurs in the crankcase under heavy load. Under light load.part throttle conditions the PCV does a nice job of creating a path for oil vapors and fumes, but with an open breather on the valve cover or in airfilter it is NOT creating a vacuum in the crankcase.


A PCV is an excellent system to keep fumes down and provide for less chance of leaks, but it is not a cure for a proper breather arrangement. All engines have to breathe somehow well above the limits of a PCV.

JIM

 

Ok.......

 

I agree with Jim for a limited street/mostly race engine. If you intend to drive the car regularly with plenty of cold starts and cold weather you need a PCV.

 

You guys are raising the bar way to high. BTW - Are we doing BG this year or something else? Just bought a truck that can pull my car, so I'm in this year.

 

BG is still in the plans, but there is also some discussion about going to NC for a show the same weekend. Gotta keep our regular attendance award going. Might make both depending on if racing happens in BG.

Might hit BG for Wed night BS/Thursday racing and Thursday night BS and over to NC on Friday? It's a day drive.

JIM

 

Sounds good. I like NC.

 

PCV interesting debate. I have no PCV and occasionally get a slight mist of oil on my valve covers under the breathers...and I'm all street very limited track use.

 

Well people led you astray. Some people think critical thinking is being critical. If you have a question that's really a question, go for it. Not interested any longer in questions that are really uninformed statements in disquise. When are you going to change your avatar to a Corvette? It only takes a moment.

 

Somehow I don't think so for this car! We are putting in a thermostat though so we can warm up the BB motor in this nippy weather.

DP

 

You sure are looking shiny BTW. Glad your project has come to a conclusion. Looks great.

Doug

 

Sorry that wasn't a backhanded statement, I always throw the PCV system in trash but some people think that's madness

 

For your combo I'd definitely stick a PCV on it. Won't hurt a thing and will help that misting issue.

JIM

 

Thanks, Doug. No conclusion yet though. Still putting things back together. Being all apart I see the things that have been bugging me for years but not bad enough to warrant tearing it apart. In other words, I'm deep in the "while I'm at it".

 

This is great! Looks like 2010 will be a great cruise year. Doug will have Bruiser done, Zwede will have the FI454 car back on the road, DVG73 (other Doug) will have his 383/6 speed car back on the road, and all I need to do is replace a rear bearing (Mike Dyer needed). All we need now is for Nick to buy a car, Patrick to put his hood on, and Jim to get us a Beech Bend sponsor.

 

...And I need to move my *** down to Texas so I can join in the fun!