CRANKCASE VENTILATION SYSTEMS

[Musicman]

Just thought I would start a new argument here... excuse me, I meant to say start a new topic  

I was just wondering what basic type of crankcase ventilation system most folks were running on there engines...

[John_Kunkel]

I like the closed system, less chance of pulling crud into the crankcase.

[tan top]

closed  , stock 69 set up 

[Silver R/T]

My 68 is closed and pretty much every car produced now is closed. Unless someone puts a breather on their system

[A383Wing]

Of the 10 cars we got here...all are closed systems except the black 66 and the Metropolitan...those are open style

[elacruze]

Mine will be closed, although with more capacity than stock.

[resq302]

stock set up for me.

[Musicman]

Huh... with all the performance builds on this site, I thought for sure that there would be at least a few folks who are running a naturally vented system with filtered breathers. Then again, not to many folks have responded thus far either... apparently only a few guys here have engines that are actually running and require some form of crankcase ventilation

[b5blue]

  Stock for me...

[speedfreak68]

Mine has masking tape over the holes...it doesn't run... 

[hemigeno]

One open and two closed systems here. 

The open system (1960 2-ton truck) was originally a true vented system, with a "draft tube" setup off the passenger's side valve cover rather than a PCV plumbed to the carburetor.  The draft tube was about 3/4" diameter, made out of potmetal, went down the backside of the engine, and had a beveled cut which opened up into the airflow beneath the chassis so that while travelling down the road it would "draw out" excess crankshaft chamber gasses and blowby.  The driver's side valve cover just had a vented oil fill cap.  I've since replaced the draft tube with a PCV going to the rear carburetor (open-style), although I suppose it really doesn't make that much difference.

The other two cars are sporting their original 1969-style closed systems.

[squeakfinder]

Open system. It was just easier with the KN style air cleaner.

[mally69]

i run an open system, im curious about some of performace builds also.

[b5blue]

While it's a topic, is there a advantage to any type of system? (other than burning crankcase fumes) 

[Musicman]

Only from an emissions standpoint really... Originally, all engines ran a vented system (many commercial vehicles still do)... an open vented cap on one side of the block and a draft tube on the other. The draft tube hung low under the engine in most cases, and was cut in such a way as to create a vacuum when the car was rolling down the highway. Since it wasn't a filtered system, the draft tube pulled oil and fuel vapors from the crankcase and deposited them on the highway below, resulting in the black stripe down the middle of the road that we are all so familiar with. As I said, many commercial vehicles, which are immune to the emissions standards that you & I must abide by, still use this system. Way back when however, it became an emissions standard that all vehicles manufactured for us regular folk had to have some form of a recirc system. Bottom line... the recirc system is an emissions standard. I know some of the true performance minded guys might say that they don't want that crap mixing in with their fuel charge, so they prefer a vented system which uses filters to handle fuel and oil vapors, while keeping dirt out of the crankcase. On the other hand, some folks may live in a state where emissions standards still apply to their classic vehicle, and therefore have no say in the matter one way or the other. Recirc systems work just fine as long as everything is working as it should, the PCV valve in particular. As far as any advantage to one system or another... a closed system uses the engines air filter to clean the air entering the crankcase, keeping dirt out. You might have to clean or change out your air filter a little more often, but who cares really. Many open systems used an open unfiltered breather originally for letting air into the crankcase, but obviously a filtered breather would be a better choice these days, again requiring you to change filters on a regular basis. Modern day vented systems work just fine as too, as long as you keep your filters clean and well maintained.

Obviously... any system that is not maintained will develop issues and can create problems. We could sit and talk all night about the advantages and disadvantages of each when things AREN'T working as they should, but with a little extra effort and proper maintenance, any of these systems will get the job done.

[69rtse4spd]

Vented on the 70, stock on the two 69s. What about a vacum  system?. A friend of mine took a smog pump off of a late 80s Chevy pick up, & put it on his race car. The system worked ok, the car picked up a few thousands, as I recall. The wheels are turning.   

[mally69]

is there anything bad about running a vented system??

[Musicman]

Not as long as you keep your filters clean, but of course this is true of any system really.

The EPA doesn't like it because you are potentially venting fuel vapor (blow-by at piston rings) into the atmosphere.
The PCV valved recirc system on the crankcase, and the EGR recirc system in the exhaust are very similar in this respect.

[Rolling_Thunder]

Mine is an open system...   I replaced the air box tube with a K&N small filter...      (6.1 Hemi) 

[J-440]

  Mine's open as well.  I have 2 -6 hoses coming from each valve cover running to a vent/drain reservoir mounted to the passenger side inner fenderwell.  The car will be road raced and s-charged and the stock setup won't cut it.   

[firefighter3931]

I've allways run a vented system.....PCV valves are ineffective at high rpm anyway. I'm not too thrilled about pulling oil vapor into the combustion chamber either so I won't use a PCV valve on any "performance" build. 


Ron

[Musicman]

Well, since I started this thread, I may as well contribute...

Both my current 383 and my new 6-Pack build run on fully vented systems

[b5blue]

On a side note be sure to match the center carb gasket to the base of the carb as I had one that did not cover the bases milled in slot and left a tiny vacuum leak that drove me insane trying to find. 

[BBKNARF]

Vented on a higher performance engine.

[Bossman963]

mines is modified but using a stock closed system 68 Charger