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I'm building a chev 350. I wanted to use an old set of California custom valve covers with no breather or pcv holes. I have an old stlye Edelbrock intake with the hole at the front for the oil filler/breather pipe.
My question is do I need the PCV valve ? If so where can I put it if not in the valve covers?
Find a place either through the intake manifold where it won't go through a water or fuel runner or the back of the block under the intake and drill and tap a hole into the rear of the lifter valley.
What Mike suggests is the way most folks will do the job. However, it does put more burden on you to maintain your engine. It's especially important if most of your driving will be lower speed, stop & go, etc. You'll need to stay on top of your oil changes.
Reason is you'll be venting at the front and the rear of the lifter valley. The air will take the path of least resistance. This setup will favor the air circulated in the valley, and only get the crankcase and upper head air by "bleed over", in a sense you're not getting "positive" crankcase venting. It's a relatively short path from the crankcase to the valley, so that won't be as bad a potential problem as the upper part of the heads (where the rockers are). There will always be some circulation, but less than the ideal where the in and out are in the valve covers.
Bobs right, this method was done on the early factory PVC system and is NOT the optimum set up for the reasons he explains. (But the only way I know of without having holes in the VCs)
One other MAJOR point is take the car out regulary at get it up to full operating temperature for extended periods of time, this goes a long way in helping to prevent sludge build up.
If you drill through the intake fabricate a metal shield or baffle and attach it to the underside with a slight standoff. This will not prevent but it will help you keep oil out of the PCV.
Consider breather vents on the side of your valve covers and a cap on the oil fill. This will bring the air flow through the heads.
PCV equipped motors are cleaner inside and the oil has less condinsate (water) in it. Condinsate in the oil reduces it's lubricating ability and promotes wear. So, a good PCV system is something you should want.
in 66 on chevy they put the pvc valve close to the top of the oil filler tube. I can't see any reason why you couldn't do the same since your manifold has the filler hole at the front already.
run a pcv valve to the dip stick tube. never seen it done, but you need to get outside the box sometimes. :cool: :HMMM:
Maybe a clarification would help based on the '66 example. You need to have an in portal, and an out portal to have cross ventilation. Sorta like trying to cool off your house on a summer's night. You won't get much if you open two windows next to each other. The ideal is at opposite sides of the engine (side to side, front to back, whatever) Typically the hose leading from a vent, be it a cap on the valve cover or the fill pipe itself, is the intake supply that connects to the air filter for filtered air. See this for concept; http://www.clubhotrod.com/forums/att...&postid=100112
To go along with Steve and Mike, those of us who are old enough to have worked on pre-PCV engines remember all the sludge build up we'd see on rocker assemblies in particular. These were on engines that had no ventilation at the valve covers. Moisture and other by-products of combustion joined to form acids that led to the formation, along with particulates, of sludge. Modern oil formulations do a better job of inhibiting sludge formation, along with unleaded gasoline, but the PCV and concurrent venting of the valve cover area, have a lot to do with it.
Thanks for all the responses. I'm not wild about the idea of drilling holes in an otherwise mint vintage Edelbrock intake , plus in looking for locations to physically make the hole it would not end up being very nice to look at.
I also agree that it would still not vent the valve cover area properly.
In looking at the engine I have an orange block, aluminum heads and intake , so I think a nice orange painted valve cover would look nice considering it will be an old school build with lakester headers.
Does anyone know where I can buy the old style steel valve cover with " chevrolet " stamped in and painted silver but still has a PCV hole in each cover ? Here's a link to a current auction for a set
http://cgi.ebay.com/ebaymotors/EARLY...QQcmdZViewItem
Could I make a hole somewhere in these for a PCV grommet ?
Yes, I would put a PCV into one & a vent on the other one.
If you just cut a hole for the breather and the PCV valve, there is a good possibility of sucking oil through the PCV if there isn't a baffle.Quote:
Originally posted by coogan
Could I make a hole somewhere in these for a PCV grommet ?
*edit* It looks like there are some grommets with intergral baffles.
link to products
Don't mess around with this. Vent one valve cover and PCV the other side, both with a baffle as cited above. Remember you need a breather AND suction (PCV) to properly control crankcase pressures.
Keep an eye on your PCV uptake. In some cases you may need more baffling to control burning oil through your manifold or spewing it out of your breather.
Regards, Kitz
So what happens if you were to simply vent both valve covers with baffled grommets?
That would work fine if one of them were hooked to manifold vacuum or a syphon device (like the old road draft tubes) to induce air flow.Quote:
Originally Posted by Jeepzilla
i use a moon breather and pcv in the manifold. i ran a clear tube to keep track of oil. this is about 6k miles and still no leaks from mains. i dont like holes either :)
how do you know if your pcv system needs a breather cap? i heard there are open and closed pcv systems? How can you tell the diff?
ok. thanx, just wondering cuz i didnt know there was two kinds.
Can anybody go over the basic's of vacuum. Typical where's what's and how's of hooking up lines correctly on a Gen I SBC, basic aftermarket (say Edelbrock/Edelbrock) intake/carb and swap meet valve covers. Start with "this is how it will work" and maybe later we can get into "this is how it will work, best for __________ (<- enviroment, smog tests, performance, daily driving, MPG, ect ect).
it actualy melted a little denny. did it first time it warmed up, weird stuff . it's been replaced with a better hose. we stuck the clear on to watch for oil. seems to work really well. i've done 8 cars this way so far. i personaly dont like the pcv system. i'd rather run it to the breather than have a vac leak under the butterflys. my next one will evac to the breather.