Hello Hamb Brothers .I know this subject has been beat to death but was just wondering if ANY of you ran your engine this way & what you encountered? First im looking to get a radical sbc built , 383 , 406 or a 427sbc( probly a DART block . Im NOT racing it , but ocassional burnouts likely . I want to run the OFFY tall finned valve covers . They do NOT have PCV valve . Spoke with OFFY rep who stated " As long as I have a manifold with the oil fill breather , I should be fine". If i can & do have room for the OFFY angle breathers , I may consider getting them mounted .I have read that those mounted on LOW side of cover may allow oil mist to escape . ASLO I read the more breathers the better . I have (3) on my 355sbc now . One on each valve cover ( one having PCV valve) & old school manilfold with oil fill breather cap ( WORKS GREAT i think) right valve cover gasket leaks constantly. But i think thats a normal thing with aftermarket finned covers & gaskets .SO HAVE ANY OF YOU RAN " JUST" THE MANIFOLD OIL FILL BREATHER WITH A 500HP ENGINE WITHOUT BLOWING OUT GASKETS ? IS VACUUM A CONCERN? THANKS BROTHERS . HAVE A GREAT DAY!
I am no expert, this is my observation. I have a fresh 283 in my car that have having oil burning issues. One of the diagnostic things we tried was just running the oil fill with the pcv blocked (back of the block connected). I noticed significant more oil leaks the short time I ran it like that. I think you need something to draw the air through the system or you will just build pressure.
I would want more than just the oil fill breather, personally. Especially on something you're building for performance and I would assume some higher RPM operation. Most of those old setups with the breather on the oil fill also had a road draft tube. I would at minimum want a breather in both valve covers to let both sides breathe. You're going to get oil mist from any breather in any location, really. But the more places vapor has to escape, the less likely it will push a gasket out. I did this for a while on my 55 with a pretty similar engine and had oil leak issues. Your results may vary. Ideally, a PCV is always a good bet on a street driven vehicle as it actually circulates fresh air through the crankcase and runs any oil vapor back through the engine to be combusted. Does your intake have a provision in the rear to drill for a PCV? It's usually a slightly elevated pad on the rear of the intake on one side. Then your filler breather becomes the entrance point for fresh air.
I WASNT GOING TO USE THE 355 intake , i would get a new one . I saw Alex Gambino running the valve covers with a tri carb intake , but he runs NO hood . Since im running a hood & engine wont be a SHOW PIECE alot of the time , its probly best i get the Breathers Mounted valve covers at least . THANKS for the responses ! The 3 breathers i got on my 355 , i have NO oil Anywhere but rear pass valve cover corner . But they are Estreet heads with after market NO NAME tall finned covers & no matter what gasket ( cork , cork with silicone , silicone blue moroso ) i run , it weeps. AGAIN THANK YOU BROTHER!!
YEAH , kinda threw me when OFFY guy made that statement. Figured i see if anybody running like that . I would think NO. More airflow the better , like you said to keep internal psi's down . THANKS & HAVE A GREAT ONE BROTHER!!
FWIW, you can get finned aluminum breather/pcv combos. I used to run the finned Edelbrock valve covers and had a set on them that looked pretty decent. If you dig around enough, I'm sure you'll find a paid that matches your valve covers pretty close.
Put the breathers on the valve covers, get a fill tube that takes a cap, and weld a bung for a line on the tube. I sliced into the tube at alternating angles a couple times, slid in some sheet metal to act as baffles, trimmed them flush, and welded them up. You can see the steel line running from the fill tube to the PCV valve on the back of the center carb. If your carb takes a hose, you could instead weld a pipe bung on the tube and use a matching Corvette PCV valve. Have you checked the leaking valve cover on a flat surface and if you find it isn't, put some sandpaper on the surface and level it out. A cut belt sander belt gives you some length to work with. Seen more than few cast covers that were not flat. .
I am unusual and think outside the box, And one combination doing an 8 quart oil change, I would fill crank case up to dipstick I have done & use multiple different ways to set up , On bolt on breathers its best to have On top side of valve cover near intake Then on bottom side near Exhaust, If near Exhaust More baffling needed & good seal , if Not oil will lay & seep out I all so run a Vent low on block near Crank , oil pan , & or vent off the fuel pump mount ,on some engine combos , Pay attention to baffling so oil not clime & push out , On tunnel ram I have mounted breathers / vents in floor / Valley of intake , If you drill or all ready hoes in covers make sure hole is Not Over rocker's If so More Baffling needed for oil climbing blowing out , Ones that have Hole or you add hole I have used a tub extension from Valve cover deep into head off roof /top to head where stud's screw or pressed in . Or Back of intake between carb & intake Pvc or Breather , What ever breather used needs to be not under sized . Or Vac pump . This Pvc works well
The big inch engine will not have the under intake oil separator or the PCV fitting at the back of the block. Only having the neck and cap at the front of the intake or breathers on the valve covers is less effective than a road draft tube, which pulls crankcase vapors when moving. It is the least effective, short of just sealing the engine and pushing out all the seals and gaskets. I get that you want the old no junk look. Since you are going big inch, big buck, you can look into catch cans and evacuation systems. They will provide even more HP and keep the inside of the engine and the oil cleaner along with less pressure which means less leaks.
Lots of ways to layout a PVC system. You just need an air inlet source and a vacuum source that are ideally separated as far apart as you can get them. But as with many things it's about managing compromises. You could get as simple as using one valve cover breather as an air inlet and modify the breather in the opposite cover by blocking off the vent and tapping into the lower part for the vacuum attachment. Either mount the PCV valve on the breather or the carb base depending on what style PCV valve you use. I wouldn't for a street driven car, but I have seen vacuum pump crankcase evacuation units on the street.
I went this route.....for vintage Offenhauser valve covers (no PCV/breather ports). I came off my passenger side breather with an inline PCV to the center carb base. I used a breather screen as a template and cut a plate from sheet metal to plug the top of the (passenger) breather and epoxied any voids around the edges to seal it off. I then stuffed the breather full with a stainless pot scrubber for a filter. The driver's side breather is unaltered so it's pulling across the engine, grabbing the crankcase pressure. Not a 500 horse mill.....but works great for my application.
THANKS ! THATS WHAT I HAVE NOW BUT NO NAME BRAND , WANTED TO SWITCH TO THE BLACK finned EDLEBROCKS BUT OUT OF STOCK & NOBODY WOULD ANSWER PHONE CALLS SO FCK EM . AGAIN THANKS! GONNA FIGURE OUT THE OFFYS COMBO SOMEHOW .
THATS A SWEET LOOK ! LIKE GAMBINOS FU54 .YES I SAW SOMEONE BUILD A EXTERNAL INLINE PCV SOMEWHERE , THOUGHT IT WAS ON HERE . THANKS THAT MAYBE THE ROUTE IM GONNA GO . COPPED YOUR IDEA & SAVED ! THANKS
SO THANKS FOR ALL THE GREAT IDEAS OF HOW TO GET THIS GOING . SEEMS LIKE EVERYONE IS USING THE PCV IN ONE WAY OR THE OTHER . NO ONE HAS SAID " YEAH RUN WITHOUT , YOU'LL BE FINE" . SO IM PRETTY SURE ITS GONNA HAVE TO BE USED IN SOME WAY .INLINE or IN VALVE COVER BREATHER SOMEWHERE .SO TO BE CLEAR , EVEN USING (3) BREATHERS ( ONE ON EACH VALVE COVER ) & ONE ON MANIFOLD OIL FILLBREATHER STYLE CAP , I " SHOULD " USE A PCV SOMEWHERE? JUST DONT GO WITH ONE BREATHER ( ie THE MANIFOLD OIL FILL BREATHER STYLE CAP)?
Breathers are not positive ventilation. So, yes if you want to manage and get rid of crankcase vapors and get rid of the crankcase moisture that causes oil sludge and goo, you need PVC.
Thanks, not my idea though. I got this system from @tommy (RIP). He was kind enough to go back and forth with me in PMs getting it lined out. Great guy....all props to him.
LMAO ! I KNOW , my sister yells at me all the time about that . I just like CAPS , not meant to be yelling . Im not a computer klicker by any means . Thanks i understand about the positive pressure & just read a post from a guy who said hes been trying to push Tay Offenhauser to making his stuff WITH a PCV application but says he just wont budge . Lol He would sell alot more stuff IMO but i get sticking to Old School Practices & design . THANKS MAN !!!( that was screamed)
A few minutes in a milling machine and you can get any ribbed valve cover fixed up to put breathers or PVC valves anywhere you want.
I love the look of 327 valve covers I've worked through the same problems to run unmolested 327 valve covers, I find accessible places on the intake manifold where you can drill and tap the 3/4 pipe thread to install chevy heater core water pump nipples, then vent to 5/8 heater core hoses into crankcase evacuation systems when running headers Running a strong big inch sbc will require large port heads with 1206 gaskets and matching large port intake manifold, I don't know of any large port sbc intakes made with oil fill tubes or pads to drill and install one. Drilled and epoxied an oil fill tube on this vortec intake, tapped manifold for the hose nipple behind the carb near the distributer try to hide the hose assembly, trying to keep a stock look, you can see the vent hose routed out near the rear of the passenger side wheel tub, untrained eyes never notice,
Forgot to note install lifter valley trays or make a baffle under hose nipples on the manifold to keep oil from splashing and getting sucked out by the evacuation system. This one is a 400 block with 3 x 2 Edelbrock intake vented, 1st installed a lifter valley tray and tapped for 2 hose nipples on the passenger side of the intake, then ran the hoses into the header crankcase evacuation system. Front hose routed over the passenger wheel tub to the header, and the rear hose behind the distributer to the header.
THANKS !! IDK where i got this photo but this is what im looking to accomplish . With or without trip carbs is OK by me .Whatever , I would like 500hp if possible or damn close .
Vented and baffled this tunnel ram for the drag engine with header evacuation system , there is no room for a front oil fill tube so it's a pain to fill again during oil changes but worth it for the 327 covers
At one time my 500+hp 355 had two breathers front, no pcv. I found when I ran the car WOT with no hood, I would get little specks of oil on my windshield. My ultimate fix was a pcv valve combined with check balls inside the breathers. The check valves allow any pressure that could build up to escape the crankcase, while not allowing outside air in. Not allowing outside air in resulted in the pcv valve drawing a vacuum inside the crankcase, which in-turn allowed me to get away with running a 12lb stock eliminator ring package on the street. Without crankcase vacuum, the low-tension engine went thru a quart of oil in less than a hundred miles. With the pcv valve drawing a vacuum, it's a quart in about 750mi. I also have a data recorder in the car, I can tell you that single pcv valve draws about 8"Hg at idle in the crankcase and about 16"Hg down the highway. Far more vac than the typical header style evacuation system, especially considering the car has a big Magnaflow muffler. You might ask how a little pcv valve could possibly keep up with blow-by @ WOT? First you must keep in mind that the car typically runs WOT less than 10sec at a time. In my case the pcv valve doesn't need to keep up with blow-by, just needs to stay ahead of it for 10sec or less. Also keep in mind that ten seconds of 20cfm blow-by is only 1.66 cubic feet, less volume than the inside of this sbc. I have data showing the 355's crankcase starting out at 12.6"Hg, then after 6.25sec of WOT it still had 3.9"Hg left. Not sure how long it would take for the crankcase to go positive pressure, but if it ever did the check valves would open up to vent it to the atmosphere. No worries about blowing gaskets. Grant
At the very least I would suggest that you visit the M E Wagner site. They manufacture an Adjustable PCV system in several configurations (I chose the in line version). The website has a ton of info on the subject and they explain why the local parts store sells so many different valves. I recently built an early Dodge Hemi that originally came with a vented oil fill cap and a road draft tube. I didn’t want oil mist being sprayed under the car so I ditched the road draft tube. After visiting the site I added four small vintage Mooneyes breather to the top edge of the valve covers. Two per side, one front and one back. I am pulling vacuum from a port on the manifold going into an adjustable PCV valve mounted in line with an M E Wagner kit. I made a simple bracket to attach it to the intake. From there, the hose attaches to the aftermarket aluminum valley pan via a grommet. M E Wagner suggests running a baffle to help keep oil from being sucked into the system. I made a small baffle per their website and then covered it with a larger baffle similar to the stock Dodge system. The motor is fresh and I am not on the road yet so I still haven’t made the final adjustments to the adjustable PCV. My first intake system was two small four barrels and it was recommended that I pull the vacuum from both. I have since converted to three Stromberg 97’s and am pulling the vacuum from a central point.
.......Tommy was a great guy indeed. Miss him very much. He was the "go to guy" here in Maryland, especially for exhaust technology and ignition help, but he was well versed in hot rod stuff of all kinds and always willing to help others. RIP @ tommy.
Yeah Don, I was on here under another member name (didn't post very much and forgot my password) in 2013 and Tommy didn't know me from squat....had a dumb question on this and he PM'd right away and walked me through it. I went back and forth with him several times on stuff that I couldn't quite get figured out. He was always glad to help....just a peach of a guy.
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