Here's the story. I bought a set of the signiture edelbrock valve covers for my small block chevy. They didnt come with any type of breather nor is there a place for one. My intake is not an early one, it has no breather. I was always told they have to be vented or it will build too much crankcase pressure. Any ideas on venting a crankcase on it or am I wrong and it will be fine?.
You need air in and out. You can add a pcv to the manifold in the back near the distributor, but you will need air in. No vents either in or out can cause seal/gasket failure.
There are some great threads on here that will tell you all about how to do it. Just do a search. I'll see if I can find one.
This one gets a little silly at the end, but the basics are there, and there are links to other threads, too. http://www.jalopyjournal.com/forum/showthread.php?t=64338&highlight=valve
Had the same issue several years ago and I drilled a hole in the intake behine the carb and put a PCV valve in. Under the intake I JB welded a small baffle and then on the front of the manifold where the flat spot is I drilled it out to accept the chrome filler tube. Works great. Several months later Street Rodder Mag. came out with a "how to" article on the same subject.
I vented an SBF crankcase once with a 44 mag just to see if it could be done. Later that day we tried it again with steel jacketed 223 it worked better and didn't make as big a hole. Yes it need to be vented, aside from blowing the seals out it also causes ring flutter to have too much crankcase pressure. You can get a pcv made to run on its side and put it into the side of the rocker cover so as not to mess up the tops and then snag a pair of old style mushroom breathers (contact DMARV) and mount them into the side of the other rocker cover. You'll have to baffle the pcv but its doable. You still have to figure a way to add oil. Mayeb a tinny little funnel and add it trhough the dipstick tube.
Heh! I had to do it like that for a while. Pain in the ***! Like the guys says a couple posts up, you can make a hole for a PCV valve in the manifold between the carb and the dizzy and then when you need to put in oil, you just pop out the PCV valve and put it in the hole.
Not to hi-jack this thread, but I have a question. I have a late model sbc with no hole cal custom valve covers and old offy intake with filler tube. Do I need a pcv valve or can I just rely on the breather cap and install some side mount breathers on the valve covers?
I got a girl to do that when I worked at the parts store. I never told her about the 710 hole. One of the best pranks, ever.
I have essentially the same setup on my roadster. You can use the breather cap OK but you will get some oil "mist" on things. Best bet is to do some sort of unobtrusive PCV valve and allow the breather to be your air inlet.
Is this an early SBC that used to have road draft tube? If so you can run grommet (with a baffle) in that hole with a PCV valve to a vacuum on the carb, but you'll also need to have the old type oil filler tube on the front of the engine. You'll need to run an intake with a place for it. Sound like it would be easier for you to get those valve covers with the breather holes...
You can get a PCV valve that is threaded 1/8 pipe at most autoparts stores. It'll be on the Fram rack with the fuel filters. @ $5-7. Drill and tap your manifold at the back for it if you have an oil fill at the front..... I have a newer intake on mine....so I drilled the back of the manifold for a fill tube (shortened) and drilled/tapped the front for a PCV.....works well, as I'm using no hole, Cal Custom finned V/C's......
I have a nice pair of no-hole Cal-Customs and I'm thinking of using two pieces of medium diameter brake line and running them from under the covers in the upper rear. Then run those to a T fitting behind the carb for the PCV valve. That's with an older style "oil fill in front" type intake. I might be able to get by with just one, but since the tubing is so small it might be better to run from both heads. My plan is to stack two thick cork rocker arm cover gaskets, but cutting a slot in the top one for the brake line to sit in... some gasket sealer around it and the cover should hold it in. If I do it before Summer I'll let you know how it goes. I see no reason why it won't work... JOE
I always thought a nascar style crossover tube with a small Motorcycle type air cleaner on it was cool. I would cut into those fancy new but obviously flawed valvcovers. Or perhaps find a 1968 and older 4B intake with the oil filler in the intake. I have one but it matches the 327 in the garage.
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