Maybe this is a silly question, but I can't figure this out. I put new aluminum valve covers on my 455 that have no vent holes so consequently have no place for the PCV valve. I have an Edelbrock dual plane intake on it that has no place for a PCV valve or other engine vent. So how do I vent this thing? I'm thinking put a vent cap on the oil filler tube? I'd hate to drill a hole in those valve covers. They have "oldsmobile printed on them and I'd have to drill it in the middle of the 'm'. Ideas?

 

I don't know which valve covers you have, but some of the aluminum covers had a knock out cast into them. If yours has that look on the underside for the location, it would have a ridge around it and be "D" shaped. Once that is cut out and the sides smoothed you can put the gromment in for a breather.
John

 

No...no knock out. Solid all the way.

 

I had a old oil filler tube, that hade a fitting on the side. Now that you mention it, I thought it was a factory one, but maybe someone made it? I may still have it, will look for it.

 

there has to be a way for air to enter to the block as well as evacuating it. typically air enters one valve cover and exits the other.

solid valve covers were normal when engines had an open breather at the oil fill tube and used a road draft tube at the rear of the block. then along came emission controls and closed crankcases.

 

So this is a 1968 engine. The original valve covers have a PCV valve and vent in the same valve cover. If I vent the engine at the oil fill tube do I even need a PCV valve? I can block off the tube at the carburator which should take care of the vacuum issue. Will that single vent suffice?

 

Years ago I had a set of that type valve covers on a 455 in my 65 442. There was an angled aluminium vent screwed on the downhill side of each,and holes drilled behind each.They worked pretty good,but every once in a while they would fill with oil and make a mess.I am sure there was a way around it,but I just took them off.I think I saw them the other day,if I find them,I will post pics. They did look cool. ---bil

 

in my 69 manual as on my 455.
It showing a circulation diagram.
it enters on the passenger side ( that hose goes to the aircleaner) and it circulate out of the drivers side ( hose to the carb)

It also tells that i must install a propper cap on the oiltube that does'nt ventilate

i run a edelbrock air cleaner also, but mounted a open filter on the passengerside valvecover

 

If you have aftermarket valve covers contact the manufacturer and ask them how you run PCV with their valve covers. They should have a solution. If not, then maybe you could go back to stock valve covers until you figure out a solution.

 

They're actually GM valve covers. Can't go back to the stockers as they won't fit over the roller rockers I've installed. I'm just going to have a hole drilled in one of them. Nothing else I can do. No other way I can see to vent this thing.

 

You can drill holes in inconspicuous places in each cover that are high-up (to reduce oil leakage) and put brass hose barb fittings through them, with nuts on the inside to retain them, then run a hose from one to a vent filter either inside or outside the air cleaner and the other through a PCV to the Carb base fitting. Or, you could just drill one cover, and put the other connection through the oil fill tube (might not vent as fully).

- Eric

 

That's a good idea. Never thought of running the PVC valve like that. Could get away with a smaller fitting in the valve cover that way I think. Thanks!

 

I guess nobody ever said GM engineers were smart.

 

Can you post a picture of these valve covers? I'm not picturing a factory cover without a breather port

John

 

They're not factory. They're GM aftermarket. Tall cast aluminum with oldsmobile script and the olds rocket emblem. Fit all big block engines. I shouldve paid attention to what I was buying but I got overcome by what I call the raccoon syndrome...ohhh shiny...

 

If you bought them used, you might have 2 left side covers, and the other guy has a well-ventilated Olds motor!!
My nephew installed roller rockers, and found ONE hitting the valve cover - although double gaskets worked, went ahead and found a spacer to raise it even more.
I guess his Edelbrock heads have a higher ridge to mount the VC's, but the spacers work on both.
Sorry, don't know where he got them, but he orders from Summit a lot - -
Could use your originals w/spacers, and cover the ventilation issue!

 

I've had this condition before as well.

 

It would have to be quite a spacer. Besides the fact that they're to short I really don't want to use them because I have these nice new aluminum ones that cost me a pretty penny.

 

It's not as simple as drilling a hole for a pcv valve.

There is also an air dam known as a "baffle" that must be installed, or else the pcv will just suck all the oil out of the valve cover and send it to be burned.

Burnt oil, even just a little bit, will cake up on the valves and really mess up the air flow.

 

I don't think there is a baffle in the original valve covers. May be wrong though I'll check it out. Seems it would take a lot of vacuum to pull that much oil out of the valve covers. Been doing some reading on a chevy board and several have recommended drilling the oil filler tube and putting a pcv there. And I think I'll drill a hole in one of the covers and put a push in vent cap in it. Should suffice.

 

I don't think Chevys have an oil fill tube like the Oldsmobile does. I have seen images of Chevy engines with a longer than stock extension to the oil fill spout on the valve cover though, this might be what they were referring to.

 

early small blocks did. My old 283.

 

I was thinking old 327s did but I might have been confusing it with the 283. Either way dont see why it wouldn't work.

 

Re the chev idea,

that is a common thing with flatheads. there were two setups with the flatheads for road draft tubes, the later had them come from the intake, so alot of people go for the early intake as it looks cleaner, but then they run into the road draft tube issue and have no venting for the motor.

the most common way is to add a PCV to the fuel pump stand, but the one I use to keep things looking nice is to do it in the valley. not suggesting you can do that but you can see from the photos the idea behind it all.

this is a photo that was showing the idea behind a bell crank for the linkage, but you can see the breather stand and the plate bolted to it and the hose running to vacuum.

IMGP2949.jpg

the tube is the vent tube coming from the crankcase, its capped off then a piece of strap welded to it , drill and tap and run a hose to the intake runners to give you the vacuum. not sure on what you would run to get the fresh air in there though.

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this may or may not help, but given 'we' flathead people have no vavle covers to vent we have to come up with other solutions to the same problem you have.