Couple of questions regarding venting the SBC and an oil filler tube source...

First off the easy one, where can I get a chrome oil filler tube for an early SBC intake manifold? And don't say Ebay, I fucking hate Ebay and Paypal due to their anti-gun philosophies and monetary donations to anti-gun organizations. Nothing really came up with a quick google search. I'd really like to spend my money with a Hamb Alliance Member if possible if I have to buy new. Or if you have one laying around, send it to me and I'll send you some magic beans.


Next, how to vent an early SBC. Here's a little background...I've got a mid to late 70's small block chevy that had a pcv and an oil cap on one valve cover and a push in breather on the other. I'm swapping in some early vette valve covers with no holes in them and an early Edelbrock Torker intake manifold with the oil filler tube in the manifold. Is a push in breather cap on the oil filler tube enough venting or do I need to do more? This might be a stupid question, but better safe than sorry.


As always, thanks a bunch in advance for any and all help and suggestions. And thanks for this great forum.

 

the oil fill tube is available from mr gasket , part # 2066...the push on cap is #2060

jeg's or summit should have them

i suggest you think seriously about adding a PCV valve . the push on breather cap will be enough venting , but there will be vapor and oil mist around it..enough that you will be cleaning it up after every trip. i had a front oil fill with no PCV or road draft tube on a 283 years ago and had that until i added one. until i did i put a scrunchie around the cap/tube to soak up the oil mist

 

Dickster has some cool fill tubes!!!

 

The tube and breather at the front is available from Mr Gasket.

The tube is supposed to draw in the air, hence the filter. The PCV draws the nasty air back into the carb to be burned out the exhaust.

WTF is up with these keywords?

 

I ran the same covers for a long time,i used a mr gasket tube,then i drilled a hole in the side and ran an in line pcv with no problems.without the pcv it gets messy.you will still get a little vapor out of it but not too much.

 

Use a Corvette breather tube, it has a hose nipple on the side of it. then you can run an pcv inline to the carb. You can buy these from any Corvette restoration sites.

 

ha!ha! Bet yer girl was not happy her scrunchie came up missing!

 

Lol, google 'squidbillies'.


Thanks everybody for the replies. I've got an old oil fill tube, but just want a chrome one. Since I've got the pcv valve already, I guess I'll rig it up with the oil fill tube in the new (old) intake manifold.

 

hmmmm...the vette tube with the hose fitting is designed to be used with a sealed cap. If you put a breather on it, and connect the pcv hose there, it's gonna suck air in from the breather cap, not from the crankcase, right?

The early vent system sure works better on early blocks....

 

Good point. Thanks.

 

So, thinking out loud and making sure I've got this straight, one option is to use a breather cap on the oil fill tube, no pcv valve and a wristband to soak up the mist that will be blown out through the vented oil cap from the crankcase.

The other is to plumb in a pcv valve. But I don't see how I can easily use a sealed cap on the oil fill tube. Sure, I could put the pcv inline with the oil fill tube to the carb and a sealed cap. But where does air get sucked in from to create the vacuum with the sealed cap and non vented valve covers? A vented oil fill cap with the pcv valve also on the oil fill tube won't really be doing anything like squirrel suggested. There's no holes on the new (old) intake manifold to facilitate a vent (for a sealed oil fill cap) or a fitting for a pcv valve (for a vented oil fill cap) that would allow proper air flow.

Am I understanding the pcv valve's operation correctly? Option one means oil gets pushed out throug the fill tube and option two has to be circular (air has to come in through a vent and unburnt gas/oil out through the pcv valve into the carb). Is there an easy way to do this I'm missing? And thanks again for the help.

 

And for the record, I do not want to cut up these corvette valve covers.

 

You need an access hole to the crankcase somewhere for the PCV, preferably at the opposite end of the engine from the breather, to vent the entire crankcase area. Tapping into the valley behind the carburetor through the floor of the manifold is one solution. A PCV in a length of hose connected to a baffled vent tube through the side of the pan is another.

If your carburetor doesn't have a PCV connection tube (I remember having some Holleys that contained one in the baseplate), using a carb spacer with one, or tapping the plenum under the carburetor will work nicely. Even tapping an intake runner will work, but might slightly affect mixture distribution.

 

First off, my carb is not a problem in this equation. I already had a pcv setup with the old generic valve covers. The passenger side valve cover had the pcv valve running to the carb. The driver side valve cover had a push in breather. This would take filtered air in through the driver side valve cover and push it through the crankcase venting bad stuff out of the crankcase up through the passenger valve cover through the pcv valve and into the carb to be burnt. At least this is my understanding of how a proper pcv system should work.

I've been searching and reading a lot of threads on this and it seems there's no easy answer for my situation. That is getting air in and out with non-vented valve covers on a newer (pre-'87) small block chevy. Some guys tried drilling the valley of the intake manifold and running the pcv from there to the carb with a vented breather cap on the oil fill tube for the intake. They reported some oil consumption (too much oil flying around in the valley) and smoking (oil going through the carb). This is at least a circular system although the output is in the wrong place or the baffle they are using is not sufficient at keeping oil from being sucked out.

Some tried just the vented oil filler cap and no pcv and reported massive oil puking out the cap/dipstick and/or blowing seals (front of the intake manifold, oil pan, or valve covers). This is just sucking air in with no escape. Well, until you find out where your weakest gasket/seal is.

Others came up with all sorts of over complicated pcv plumbing (through the oil pan or fuel pump block off plate) with no real conclusive results shown. Most of these were just excercises in expirimental design that may or may not work and the effort to install didn't seem worth it for possibly the same outcome as the valley drillers.

I'm starting to think there really is no good way to run a pcv system without going through at least one valve cover. This sucks. I love these valve covers and don't want to "ugly" them up.

 

Maybe a hole in the valley at the rear of the intake manifold for the vent and a bung in the oil filler tube for the pcv to go to the carb would work better? Just thinking out loud. I think all the other valley drillers that were having problems did it the other way around. Would the filler tube suck oil up and blow it out the pcv as in the case of the pcv off a hole on the intake manifold? Or in other words, would the "going up the filler tube" before going to the pcv lessen oil getting out of the engine?

 

Just an idea,but could you ,as previously mentioned,drill the intake to mount the PCV in the valley area but fabricate an internal baffle around it to hopefully cut down the excess oil consumtion,just like in a factory valve cover?
You could possibly weld a couple of threaded bosses to the underside of the intake and bolt on a shroud formed from sheet metal.

 

If you live in an area of constant high humidity, like I do, the PCV system is very important. What ever you decide to do, after a couple weeks of driving, pull off one of your valve covers and look inside it. If it has a coating of whitish slime on it you have failed to design an adaquite system. One of the main reasons Chevrolet redesigned the PCV system in the late 60's was the early system did not do a good job of removing moisture from the valve cover area, which caused a lot of valve covers to have rust holes after a few years.

 

Several years ago (5?) SRM ran an article on this very subject. It showed how to drill and tap the intake manifold (not the runners, obviously) and install a PCV valve from a Nissan or Infinity (can't remember details). I tried it on my SBC and it works fine in conjunction with a breather cap on the fill tube and old style (no filler or pcv) valve covers. I still get a little occasional seepage around the oil pan, but I attribute that to my questionable engine assembly skills.

 

speedway sells the chrome filler tube but dont buy there filter cap(they dont fit tight)buy a stock cap and paint

 

Also, check into a mid-sixties Corvette setup (try Mid-America or Ecklers) They used a manifold mounted oil fill tube that had a bung made in it for a screw-in PCV valve.

 

That would work, but there still has to be a seperate inlet. Air can't go in and come out the same passage at the same time.

 

65 corvette has the threaded pvc There has been alot of threads on this.You also can drill manifold and tap .Making sure your in the valley area .You will have to fabricate some type of baffle

 

Right now, this is going to be the only option to try. Others were talking about making baffles out of brillo stuffed in the fitting before the pcv to keep oil in with only so-so results.

By using a valve cover type baffle like you described, it seems like it should work. But with this method, I don't have any aluminum welding capabilities. Could a baffle be attached with some sheet metal screws to the underside of the intake manifold? That's the way it's done with some of the aftermarket valve covers, although the baffle is screwed to a bracket that is spot welded to the inside of the valve cover. I'd imagine the screws would have to be really short so as not to go through the top of the manifold. I wonder how well that would hold up over time?

 

this is what ill end up doing also, drill into and open area behind the carb for the pcv. hook to carb. breather cap on fill tube. i dont have aluminum welding skills either, but ill just fab up a lil aluminum baffle and have someone spot weld it on, wont take a shop more than 2 seconds. screws would work too, but theyd have to be real short, and id use some red loctite on em

 

I think this is your best option, a combination of screws and epoxy(JB Weld) should hold up fine. How about using a threaded hose-fitting in the back of the intake and an in-line pcv valve between it and the carb?
OOOR...you could just use an early block with the road-draft hole in the back like I did
Also....make sure you take into account the amount of vacume your engine is pulling when selecting a PCV valve.

 

I like the idea of getting an aluminium baffle welded direct to the intake.No worries about fasteners coming loose.

 

if you got the 1969 and later Vette finned aluminum valve covers, you'd solve all your problems real easily...and it wouldn't look as funky as having early covers on a late engine (some folks can actually spot the fact that it's a late engine at a glance)

 

So, here's my plan...
Drill a 1" hole in the rear of the intake manifold. Use the factory pcv rubber grommet in that hole with the pcv valve in the grommet running to the carb. I'll have to make a baffle or cut one out of the old (newer) valve cover and use some epoxy to hold it in place. I'll re-use the factory pcv valve. It's in good shape and there will be no worries with too much or too little vacuum.

I think just pushing in the grommet will be easier than threading the hole for a nipple hose fitting. Plus, I've already got the grommet so it's basically just plug and play.

I'll be sure and post results when I get done. Hopefully later tonight.

 

I'll just follow you lead and see what works on yours Terd before I start messing with mine.

I also have a '79 4 bolt main with early corvette valve covers in my '35 for right now so I think we are in a similar boat.

 

Well, let's see. Corvette valve covers are expensive. I was given these. I'm going to make them work. It totally goes against my philosophy of if it ain't broke don't fix it, but it'll make my engine bay look a little more exciting. I'm not trying to perpetrate an old motor. But seriously, it's way less boring with the vette valve covers.

Plus it'll look a whole lot like my pop's '57 chevy truck from back in '59. A sort of quasi half assed tribute to the man who got me started way back when (I couldn't find a '57 I could afford, lol).