So like everyone else, I have read many threads on this with a lot of different opinions. My particular application is some where in the middle. I'm installing a new Edelbrock carb, so I have to address the current setup (bought the car recently). On the old quadrajet, there was a tube that goes from the valve cover to the carb. I installed the new carb the same way. It has an old style oil breather tube to suck air into the engine. My question is this... Should there be an inline PCV valve installed? PO has it going straight to the carb. Is this dangerous? There is a baffle in the valve cover and it is very clean underneath, so I can only assume that the current system is functioning properly.
my only concern would be if there is NO baffle in the valve cover you may suck some oil through the line into the carb.why did you change the old carb?was it dirty because of this set up?
I did something very similar except I welded a bung into the oil fill tube like you have and vented that way since I am running Vette covers and have had it that way for years with no issues what so ever so I think you are good.
Since it is currently working, if you subscribe to the "if it ain't broke" ethos, then leave it alone. If you want to make it better, put a valve in it. The actual valve part of the PCV system is not just for show. Part of it's job is to act as a flame arrestor in the event of a backfire.
There is a baffle as stated above. I changed the old quadrajet because it had no choke, literally took forever to start and needed a rebuild. From what I have read this setup seems to be venting correctly. Wondering why everyone wouldn't forego a PCV if this works.
it looks ok to me then.i have some of those valve covers without the holes in them thats the way i want keep em.i love the looks of them.i hope that set up works for ya
that looks like a big vacumn leak . get a oil fill tube from vette supply place it has a bung on it for pcv and a seald cap wayne
If you did this you would need a breather on a valve cover to let air in. I would just put a pcv valve in what you have. Afterward you will probably have to readjust your idle.
PCV valves control the air flow also. They are designed to flow less when the vacuum is high at idle. When the vacuum drops as the load is increased, it flows more air for the increased load. You need a PCV valve in the system and as said above there must be another breather to let the fresh air in somewhere else. Your goal is to have air flow through the engine.
The above is correct.............also not all PCV valves are the same, get the correct one for your engine.
Didn't the early GMs use a PCV valve in one valve cover connected to the throttle plate and have a breather line connected to the opposite cover and the air cleaner inside the filter? Later they used a separate breather filter on the outside of the cleaner like Ford did.
Just remember, you are drawing in oil vapors and engine blow by back into your combustion chambers....and mixing it with in-coming fuel air mixture...upsetting the balance...do you realy want that stuff in there or vent it out..run it into your exhaust system like we did on the race cars. I run a long hose from my valley vent to just behind the seats, can't smell it....
What you are thinking about is a later iteration known as a "closed PCV system". This is where the air enters the engine normally through the little filter. Down through the tube into the pass VC, through the engine and out through the PCV valve in the other valve cover. Under heavy loads the PCV valve can't handle all the blow by and it backs up into the air cleaner where it is then sucked back into the engine through the air filter. If you are concerned about air pollution you can do it this way. If you are building a couple hundred thousand cars a year it can make a difference. Personally I don't think it's worth the effort on the few cars that we build. PCV valves are good for engine longevity. Sucking some blow by and oil fumes into the combustion chamber where it gets burned is a lot better than leaving the acids and water vapor inside the crankcase. IMHO
That kind of logic might impress Bubba and Leroy down at the Feed Store but makes no sense on a street driven vehicle in todays world. The car isn't a race car where you drive it for a few seconds or laps at a time and come in and wipe the oil off the engine where it blew out thebreathers and blew out the gaskets because the pressure inside the crankcase is going to go somewhere and that is usually the path of least resistance. The system you have will work fine with a proper PCV valve in it that is matched to the engine. Air in the breather on the intake, through the crankcase and out the vent in the valve cover through the PCV valve and into the intake and burned and out the exhaust. Read what Tommy wrote and follow it. In the time I have been on the HAMB I have never seen him give anyone bad advice or feed them bullshit. I can't say that for some of the others who either believe in backwoods engineering or have no clue as to how engine systems actually should work.
Thanks for the insight guys. After going to the parts store and finding an in-line PCV for a sbc, $1.99 (plus tax of course) later, I'm in business! Took all of 5 mins to install.
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