Clams Canino

OK here's my setup.

Generic small block yanked from a Chevelle. No draft tube in the back.
Valve covers from a '59 Vette - no PCV or cutouts - solid aluminum covers.

Aftermarket chrome oil filler tube in the front of a 1968 stock (I think) intake.

The breather cap on that oil filler tube is the ONLY ventilation in the entire motor.
This means that with minimal blow by, the thing mists oil out of it - not that much, but after along ride it's "notable".

My goal is to put a light vacuum on that tube to stop it from "weeping".

What I want to do is channel my inner Bubba and cut a hole in that filler tube, insert a PCV valve - and run that to the air cleaner (which has a fitting to stick a hose in it.

Thoughts?
Is there a "kit".
Also how does a PCV valve work exactly?
I found this in Fleabay - kinda what I need - only not at the cap as it would look like hell.

http://www.ebay.com/itm/Chrome-Oil-F...b327ab&vxp=mtr

-W

7T1vette

Well, that will work, but it will clog up your air filter pretty quickly. What you want to do is run a tube (PVC, hose, etc.) from the body of the air cleaner to one of the valve covers. That will be the 'fresh air supply' side of the PCV system. Then, you want to put a PCV valve in the other cover [like you described], then run a hose from the outlet of the PCV valve to a fitting on the base of your carb. There is usually a 5/16" or 3/8" fitting on the front of the Q-Jet carb base or you can use the fitting at the back of the base, which is intended for power brake booster vacuum supply....if it is not in use. That port 'receives' the oil mist blowby and burns it in the fuel charge.

Good luck.

Clams Canino

Thanks!
Since cutting a set of 1959 valve covers is not an option. I guess I'd have to go with plan B.

The inlet fitting in my air cleaner bottom is inside of the element so I would think it would not impact the AC element too much?

Can you explain how a PCV valve exactly works ie "mission statement" and practical function?

OMF

PCV= positive crankcase ventilation...... kinda self explanatory, but it's to vent the crankcase of blowby, and to burn that blowby by recycling it through the engine again instead of venting to the atmosphere.

Clams Canino

I get that.
I was speaking to the valve - in it's normal operation.
Why is it there and how does it work?

-W (remember - I never had one)

scottyp99

http://en.wikipedia.org/wiki/Crankca...ilation_system

noonie

You have 2 problems with your proposed setup.
First you will only be trying to suck out blowby gases, leaving the crankcase still full of them (undilluted)
Second, pulling from the air cleaner is not nearly enough.

The pcv valve itself has a tapered fluted valve inside. Under high vacuum, it allows a smaller controlled amount of flow, still allowing the engine to idle properly. Under lower vacuum or higher throttle, the valve is open more and still allows the most flow thru. Under WOT, there should be almost no vacuum and a lot of blowby so the blowby essentially pushes it thru as well as reversing thru the intake port for the pcv on the other valve cover going to the air cleaner on oem setups.

You need air intake and the pcv valve. You can drill the intake valley between the carb and the dist (not a runner) and use a threaded pcv valve going to the 3/8" pcv port on the carb. Then you can use the fill cap you linked to as the fresh air intake going to the air cleaner.

Search for an adaptation Lars did, he used a valve cover riser to mount his.

aussiejohn

My thoughts exactly. You need to allow outside air INTO the engine and this can be either filtered or unfiltered. Filtered air would have to come from the air cleaner and you said that yours has such a provision for the filtered air EXITING the AC. Unfiltered air could come from the top of the oil fill tube, providing it had some sort of hole in it.

But where does the air ENTER the engine? You could cut into the oil fill tube or into the SIDE or REAR of one of the rocker covers if you didn't want to cut into the top. As Lars did to his engine, you would need some sort of a baffle to prevent liquid oil from being drawn into the engine.

As for the air EXITING the engine via the PCV valve, I'd do as noonie said, drill a hole in front of the dissy and fit it there.

Regards from Down Under.

aussiejohn

oldalaskaman

long as you're gonna bubba it, get a valve cover oil fill cap from just bout any of them, elelbrock...etc etc...drill a pvc sized hole thru the chrome cap and then thru the rubber inner plug to custom fit your pvc valve, I used a step bit till it was the right size, install the edelbrock..etc.etc..oil fill cap on your tube, install the pvc valve in it, install a hose to the pvc valve, run that to intake vacum, done deal. if you dont like chrome a ford valve cover gromet works good too.

427V8

Where ever you put the PCV valve or vacuum line, make sure it's well baffled.
if it's not you will suck oil...a LOT of oil esp at high RPM / heavy usage

oldalaskaman

top of that tube is perfect, high enough up

lars

That won't work. The PCV needs to be hooked up to manifold vacuum. Also, if the PCV is going to provide actual crankcase ventilation, you need to position the PCV in a location which will allow fresh air to enter your fill tube breather, flow through the crankcase, and be pulled out the PCV. Locating the PCV just below the breather in the fill tube will only draw air in the breather and right out the PCV without providing any crankcase ventilation. GM put the breather in one valve cover and the PCV in the opposite side cover for a reason: you need to get some separation between the two so you create a "draft" through the crankcase.

Lars

scottyp99

Think of it like this: if you opened two windows on opposite sides of your house, and stuck a fan in one of them, blowing out, it would create a slight breeze all through the house. But, if you opened two windows right next to each other, and put a fan blowing out in one of them, it wouldn't create much of a breeze through the house at all. Likewise if you only had the one window open with the fan blowing out. This webpage has a good diagram of how the pvc system works.

http://autorepair.about.com/library/faqs/bl616h.htm


Keep the shiny side up!
Scott

69 Chevy

BTW, a PCV valve is not a one size fits all proposition. It needs to be selected by how much vacuum your engine produces.

RobbSalzmann

I had this very same problem, compounded by the large amount of vacuum created by the supercharger. My idea is similar to yours.

I started with tall valve covers that have the oil baffles.
Then I added a Chrysler Oil Separator (many of the hi perf boaters use these.).
Finally I welded the PCV inline with the Oil Separator. (You could probably connect them with heater hose if yu don't want to weld them).

Its ugly, but made a huge improvement on oil suck consumption.

63mako

I have a "bubba PCV" I have a filter on both valve covers. Oil fill tube is 66 corvette. Sealed cap. Has a tube off the oil fill tube that I have hooked to the rear of the center carb baseplate with the fitting off a 63 corvette. This fitting has a small 1/8 hole to stop this from becoming a vacumn leal. No PCV valve. Works! The air goes in both valve covers with the regulated suction at the sealed oil fill tube.

oldalaskaman

not ugly, genius

noonie

All good ideas, but you're forgetting the OP doesn't want to put holes in his 59 vette valve covers.

Clams Canino

OK
Thanks to all of you, I have a better handle on this, and more importantly I now understand the exact function of the PCV valve. That's where I was unsure of myself.

Yes, I understood up front that I was not going to get any meaningful crankcase cross-ventallation. This is a totally disposable engine that came from an 80's donor Chevelle.

My main goal is to scavenge the blow by that's currently weeping from the vented filler tube cap. (thus the term Bubba's PCV)
To that end only (and thanks to all the advice!) I'm thinking that a PCV valve in a grommet about 3/4 of the way up that tube, with hose running to the port on the front lower of the carb will pretty much do what I want.
Yes - I understand that it will mostly draw fresh air from the breather cap - but it will also stop the weepage up at that cap too.

Now the only question is what PCV valve? I'd prefer a straight one as opposed to a right-angle one.

-W

Clams Canino

Noted thanks!
Can you recommend a straight one for a small block with a Q-jet?

-W