going from breathers to non?sbc valve covers

hey guys

looking at a motor right now that has the breathers in the valve covers but would want to run the breatherless script covers i have.its got an rpm intake if that matters any but what do i need to do to make this work short of drilling in a breather?

tia
tim

 

yeah... but change the road draft tube to a PCV valve and run that to the back of the carb. SAMIYAM has this down to a science.

Travis

 

its running an edelbrock 650 performer.just run a hose from the back of the valve cover to were on the carb?

what if it were running a 70s rochester 2 barel?--gota another motor that i had to switch the intake from a 60s filltube type to a 70s stock type

 

Kustoms-n-Rockets needs to post a pic of the setup on his dads tri-power motor, it's pretty cool

 

Man, we've disected this ad-nauseum. Where've you been, Tim?? Youre not a newbie, pay attention next time, we're not in this class for your amusement ya know!
Does the block have a provision for an outlet at the back by the oil-pressure sender? Has anyone drilled a hole in the intake for an oil-filler tube?

 

I need to see this AGAIN too (memory loss due to top secret military experiments ) I'm getting my motor out of the shop next week! Bought new eldebrock finned covers, and I don't want to drill them. I have no provision for a draft tube on the block, but I do have the hole for the filler in the manifold. Can I drill the back of the manifold for the PCV?

 

On a later block with no hole in the back you can do that or drill an indescreet hole in one or both valvecovers and run a PCV to the carb.
To review for class, the chronology is sumptin like this-
first was the completely open-system; oil-filler tube with vented cap in front and road-draft tube in back. The only vacating of fumes was the draft-vacuum from the bottom of tube otherwise engine just 'breathed' thru vent cap. Next was the little 'hat' sitting on the hole where the tube was which now had a PCV on it, at low engine speed venturi vacuum sucked a little fume thru valve but beyond that it still breathed in/out thru vent cap. Eventually it got to the closed-system where the filler-tube had a sealed cap with the PCV on the side of the filler-tube and in back the little 'hat' now had a big tube that ran into the air cleaner above the carb air-horn, at low speed the carb sucked thru the PCV and at higher speed it blew/breathed thru the air cleaner.

 

The pcv valve for a 63(?) 283-327 has a 1/4" pipe thread that screws into the base of the carburator and the hose goes to that fitting on the back of the block.

 

Ryan, what Elrust said...just run that into a PCV into the carb. Old 4GCs and WCFBs had a boss on the back and the PCV threaded right onto the carb, and you can go to the autoparts store and find in-line PCVs. But youll still need to either vent out the fill-tube or the valve covers. PCVs only vacate fumes at low engine speed, higher speeds need a larger orifice(dont we all!).
...and Ive been demoted to a junior member?? Where did love go??

 

Ryan, I beleive Sam did the freze plug thing. If not I have seen that done before by someone else.

 

This is what I did.It's a 350.Intake is from 327.I drilled a hole through intake manifold and put a fitting.

 

^^^^^^^^NICE!

 

I have a similar set up in my 54 chevy. I'm running a 350 with an old street dominator holley intake. I just knocked out the freeze plug in the front of the intake and installed a breather tube then put a chrome breather on top of that. Because my motor doesn't have a provision for the draft tube I just drilled a hole in the very back of my corvette valve cover and put a grommet then a pcv valve in it. I ran a rubber hose from there to the back of my carb and I was done.

 

Sorry guys... I was away from my computer last night WORKING in my garage.

What I did on my 327 (which also has an RPM intake) is I got a freeze plug that fit into the road draft tube hole. I then drilled a hole in it and then installed a grommit in said hole. Now on other motors I've installed the PCV in that grommit and run the tube to the back of the carb. But on my 327, my valve covers and manifold didn't have a provision for fillin' the thing up with oil... so I made a piece of pipe that angled outward, had a brass cap with o-ring and a nipple off the side. I ran a tube from the nipple to the back of the carb and used a Honda "in line" PCV valve. The cap comes off to fill her up with oil and all is well. The only other thing I had to do was cut my Vette valve covers and install and old drag fast 90 degree breather. With a PCV system, you have to have a "good air in" hole and a "bad air out" (PCV) hole.

I'll try to get a pic up tonight.

Sam.

 

One thing you guys seem to have neglected: If you run a crankcase breather, a PCV is a waste of time and money, not to mention a vacuum leak. If you run a PCV valve, DO NOT run a breather.

 

Funny, they seemed to work OK from the factory.

As was mentioned, the PCV vacates a VERY small volume of air thus only doing its job at low engine speeds. Im sure the design considers the leaning-effect it has on fuel mixtures, and it was probably determined that the effect was insignificant enough, versus the benefit of a positive ventilation of the crankcase, to warrant their use. As was pointed out the last time this discussion came up, when engine speed increases beyond the volume of the PCV, youd better have something larger to vent the crankcase- like a vent cap or valve cover breathers or a road draft tube, something!- or you could have problems. The original factory design with the PCV on the sealed-cap filler-tube did this by venting the back of the crankcase into the clean side of the air filter housing, thus either venting fumes down the carb under positive pressure or allowing only filtered air into the crankcase under negative pressure. Breathers do this with their little filter elements, but the vapors are lost to the atmosphere instead of down the carb. BUT, engines have run PCVs with some sort of larger OPEN vent to the atmoshere since..., well, ALWAYS.

 

Here is what I did on a later SBC without the road-draft outlet at the rear of the block.

It has old-style Edelbrock valve covers with no openings, a Weiand intake with a front mounted oil tube and a breather cap.

The PCV is mounted in the fuel pump block off plate and is connected to the vacuum port on the base plate of the carb.

The angled PCV grommet is from a late sixties Corvette or Z28 valve cover and angles the PCV valve just enough that it fits into the recess in the block behind the block-off plate. I was a little worried that it may suck up oil, but I have a couple of hundred miles on it now and it seems fine.

I am planning to replace the rubber hose with a steel hard-line to make it a bit tidier as well.

 

I have a pair of old Cal-Custom valve covers for my 283. I didn't want to drill any holes in them either. I am using an Edelbrock RPM manifold. It has a boss in the front to allow for drilling a hole for an oil fill tube . The fill tube is topped with an oil breather cap. This allows fresh air to be drawn into the lifter valley. I have the old draft fitting and separator canister as shown in the picture from Ryan's post. I am using an inline PCV screwed into the base of the carb with a hose from there to the old fitting. This will draw the crankcase gasses through the lifter valley to the carb, with fresh air following.

 

Here I am scratching my head... I have this modification HALFWAY complete, and I think I'm gonna hit a snag...

I too, wanna run my script valvecovers... I put on an intake with a filler/vent tube. I punched the freeze plug out of the back and soldered a pipe fitting to it, ready to make a road draft tube.

... but, I was in a hurry to get back on the road, so I slapped my mullet-ass chrome edelbrock covers with push-on breathers back on, and capped my new draft tube.

So, I have THREE breathers now, but no road draft. With all that, I'm still getting a bit of squirt when I nail it, like 5k rpm. smelling it I don't mind, but wiping the oil up...

So when I go to script covers with no holes, and a raod draft tube I'm expecting more mess. I'm thinking I need to run the "Alaskan road draft pipeline" all the way out to the back of the truck... the transmission already handles all of the mid-vehicle "rust proofing."

I heard someone say they run the road draft into their exhaust. That just sounds hella wrong, like putting a tube in your ass crack and having the other end up by your nose... Fuck my driveway, I dont care about drips.

I WILL NOT use a pcv valve EVER. (maybe I'm stupid and stubborn, but) I figure the air going in needs to be clean as can be, fresh air. Also, sucking some of that oil spray down yor carb is inevitable. I've seen it first hand on the BEAST MOTOR in my vw bus... Uh uh, not gummimg my carb up.

ok, go ahead and tell me why you think i smoke crackpipe....


-J

 

You smoke crackpipe because...surely youve seen drag cars(VWs or V8s) with the hose running from the engine to a fitting on the exhaust collector? Theyre scavaging not only the exhaust but the crankcase blow-by. Works great, if youre buzzing like 6K rpms or more its like a high rpm PCV. A PCV is something which 'positively ventilates' the crankcase(ie.SUCKS the vapors/sludge/blow-by out). The early engines that didnt have one suffered sludge build-up and this was a remedy to help solve that. Running just vents is fine, I only have a fill-tube vent-cap and a road draft tube on mine, but Im not concerned with sludge on a low-use engine like mine. If I had a daily driver Id run a PCV into the carb fitting for low rpm scavaging and a large tube mounted high out of the engine into the air cleaner(INSIDE the filter element) for high rpm venting, thats the mess your getting at 5K rpms.
Crackwhore.

 

Huh...

1. road draft to exhaust only for high rpm...

2. road draft to the road gives you sludge...

3. Aha! 'Splain it to me why the minor vacuum leak of a pcv system and the big tube going straght down the carb with oily yuck is ok... I know thats how they build them, but I still dont get it... call me a misinformed idealist... or a cracked out ho, either way...

 

The PCV handles the light-duty work...low rpm, when not much is happening inside, vacuum from carb sucks at the fumes inside and removes moisture(which builds up as sludge). As rpms increase shit starts to happen, air movement combined with blow-by and oil vapors creates an increase in pressure and shit starts to FORCE its way out, eventually overpowering the PCV and it has to come out somewhere else, like the road draft tube. The stock tube hole has that internal baffle to keep oil away, like the one you found inside, but oil can barf out of the oil-fill tube if the pressure gets really high, or out the after-market valvecover vents. Theres nothing wrong with using this vapor as a component to your intake mixture(not to mention being better for the enviroment and all that shit) and thats why the manufacturers dropped the road draft tubes and started to route the shit into the air cleaner. Plus, as a hot engine cools it will suck air into the engine and so the road draft tube allows dirty unfiltered air to get drawn inside. Having the tube inside the filter means it gets just clean air.
Misinformed crackhead idealist, the best of both worlds.

 

My 327 block had the port in the back similar to the pic that Ryan posted. I ran a hose from that to a piece we welded into one of the exhaust pipes. We put a 45 degree cut on the end of the piece that extended to the inside the exhaust pipe so it created a vacumn on the hose. It is a clean set-up and worked real well.

 

So how come engines with REAL crank case evacuation systems (Header mounted, or vacuum pump) Say NOT to run a breather, and then they offer a little adjustable check valve that you can screw into the valve cover to control the amount of vacuum in the crankcase??? I was told the idea was to maintain a VACUUM in the crankcase, which IS NOT POSSIBLE with an open element breather. Explain please...

 

I took the Edelbrock manifold and drilled it up front where the casting was originally for the filler tube. I drilled it large enough to accept the valve cover grommet. Then I glued the grommet in and ran the push in pcv valve to the front of the Edelbrock carb. It was easy and worked like a champ. If you need to put oil in....just pull the pcv valve and stick the funnel in the hole. The only drawback is the intake has to be removed. I doubt you can see it in this pic but the truck is long gone now......