Valve Covers

[72Cheyenne350]

Hey guys I just bought some valve covers for my truck with stock type baffles, question: do I need blowers, if so what type do you guys recommend?

Thanks!

[GASoline71]

What are blowers?

Gary

[70STOVEBOLT]

I think he means breathers?

[72Cheyenne350]

Sorry I did mean breathers, my bad.

[El Jay]

1 side needs a breather, 1 side needs a PCV valve.

[72Cheyenne350]

Got it, I'll add those to the order. I'm going to say the pcv valve hooks up to the air cleaner?

[cdowns]

Originally Posted by 72Cheyenne350

Got it, I'll add those to the order. I'm going to say the pcv valve hooks up to the air cleaner?

i'd suggest some reading// either you can buy a factory service manual loaded with info or if that $25 investment is too steep for you try a local library for a generic manual read up on different stuff like how a crankcase ventalation system works, how a brake system functions, air fuel timing trilogy ,to get at least some of the most basic concepts down

[72Cheyenne350]

Cdowns: I found a chilton's manual at the local kragen with a range from 70-79. the issue with it was that it was focused more on the 78-79 models. Any suggestion as to where I can find a specific manual for the 72?

Thanks.

[cdowns]

on the main page here theres a list of board vendors most stock quality reprints of the original factory service manuals and pretty cheap prices well worth the investment and loaded with great info

[piecesparts]

The PCV valve does NOT hook up to the air cleaner. The true closed system for a PCV system is to have the top of the PCV valve run to the carburetor base (going directly into the intake manifold) and the other valve cover's cap going to the air cleaner to make sure that your fumes and oil does not get out onto the engine. However, if you get just a standard breather cap for the opposite side, then it will pull air from the atmosphere.

[junkyardjohn]

Originally Posted by piecesparts

The PCV valve does NOT hook up to the air cleaner. The true closed system for a PCV system is to have the top of the PCV valve run to the carburetor base (going directly into the intake manifold) and the other valve cover's cap going to the air cleaner to make sure that your fumes and oil does not get out onto the engine. However, if you get just a standard breather cap for the opposite side, then it will pull air from the atmosphere.

SOME MODELS DO INDEED GO TO THE AIR CLEANER. CDOWNS IS RIGHT AGAIN ABOUT LEARNING & UNDERSTANDING OF ALL THOSE LITTLE PARTS. (AMAZING HOW SOME FOLKS JUST DON'T GIVE B.S. ADVICE HUH??) I REMEMBER WAY BACK WHEN I WAS A KID & BUILT A WORKING MODEL CALLED ''THE VISABLE V-8". IT SHOWED ME HOW ALL THE LITTLE PARTS WORKED IN CONCERT WITH EACH OTHER. ONCE YOU UNDERSTAND THEM YOU REALIZE THAT THERE NOTHING MYSTERIOS OR MAJICAL THAT GOES ON UNDER THAT CAST IRON & TIN. ( MOST MOTORS ONLY HAVE A PVC VALVE OR A BREATHER. NOT BOTH. IT'S AN EXIT. THE MOTOR GETS PLENTY OF AIR TO BREATH RIGHT THRU THE CARB.) SHOOT I REMEMBER THEM NOT HAVING PVC VALVES OR BREATHERS AT ALL. THEY HAD WHAT WERE CALLED "ROAD DRAFT TUBES" THEY WERE BASICALLY JUST AN EXIT TUBE THAT DUMPED BUILT UP GASSES & FUMES FROM THE INTERNAL COMBUSTION PROCESS RIGHT OUT ON THE ROAD. IMAGINE THAT B.P. JOHN

[michael bustamante]

Im running a pcv to the carb and a oil cap on the other side myself, never any problems, if you try just running a breather though youll get blow by out the breather, (from my experience)

[piecesparts]

Originally Posted by junkyardjohn

SOME MODELS DO INDEED GO TO THE AIR CLEANER. CDOWNS IS RIGHT AGAIN ABOUT LEARNING & UNDERSTANDING OF ALL THOSE LITTLE PARTS. (AMAZING HOW SOME FOLKS JUST DON'T GIVE B.S. ADVICE HUH??) I REMEMBER WAY BACK WHEN I WAS A KID & BUILT A WORKING MODEL CALLED ''THE VISABLE V-8". IT SHOWED ME HOW ALL THE LITTLE PARTS WORKED IN CONCERT WITH EACH OTHER. ONCE YOU UNDERSTAND THEM YOU REALIZE THAT THERE NOTHING MYSTERIOS OR MAJICAL THAT GOES ON UNDER THAT CAST IRON & TIN. ( MOST MOTORS ONLY HAVE A PVC VALVE OR A BREATHER. NOT BOTH. IT'S AN EXIT. THE MOTOR GETS PLENTY OF AIR TO BREATH RIGHT THRU THE CARB.) SHOOT I REMEMBER THEM NOT HAVING PVC VALVES OR BREATHERS AT ALL. THEY HAD WHAT WERE CALLED "ROAD DRAFT TUBES" THEY WERE BASICALLY JUST AN EXIT TUBE THAT DUMPED BUILT UP GASSES & FUMES FROM THE INTERNAL COMBUSTION PROCESS RIGHT OUT ON THE ROAD. IMAGINE THAT B.P. JOHN

I would beg to differ with part of your input here. The air that goes through the carb has nothing to do with ventilating the crankcase, it is combustion air only. The air intake on one side of the engine (valve cover breather or hose to air cleaner) is the inlet and th eother side is the PCV valve with a vacuum source to purge the oil fumes from the engine. A slight negative pressure is desired on most engines and that also helps to make the seals on the engine work more effectively. The older style engines with visible tubes coming off of the crankcase was always blowing oil fumes and creating sludge, but in those days there were no laws or engineering behind it.

If you have never witnessed a crankcase fire or a engine running off of it's own crankcase fumes, then it is hard to fathom, what I am referring to. I make a special effort to purge my engines and they virtually stay clean for miles.

[72Cheyenne350]

My truck has the original engine in it. Right now I have one valve cover with a breather and the other just spewing oil fumes which definitely can not be good for the engine. I bought the truck this way so I don't know if the pcv was hooked up to the air cleaner or carb but I've read it hooks up to the air cleaner, back to the drawing board for more reasearch and definitely a manual. Tons of info guys thanks for all the input, advice and info.

[El Jay]

The air cleaner line is actually the breather. It comes off the air cleaner so that clean air is getting sucked into the engine.
A breather on the valve cover serves the same purpose, clean air into the crankcase.

The PCV valve is connected to the carburetor and the valve is closed during high manifold vacuum conditions.

[junkyardjohn]

Originally Posted by piecesparts

I would beg to differ with part of your input here. The air that goes through the carb has nothing to do with ventilating the crankcase, it is combustion air only. The air intake on one side of the engine (valve cover breather or hose to air cleaner) is the inlet and th eother side is the PCV valve with a vacuum source to purge the oil fumes from the engine. A slight negative pressure is desired on most engines and that also helps to make the seals on the engine work more effectively. The older style engines with visible tubes coming off of the crankcase was always blowing oil fumes and creating sludge, but in those days there were no laws or engineering behind it.
If you have never witnessed a crankcase fire or a engine running off of it's own crankcase fumes, then it is hard to fathom, what I am referring to. I make a special effort to purge my engines and they virtually stay clean for miles.

PIECESPARTS-- I HAVE NEITHER THE TIME OR INCLINATION TO DEBATE OR EDUCATE YOU ON THE INNER WORKINGS OF AN INTERNAL COMBUSTION ENGINE. DO A LITTLE RESEARCH. ALL THE WORLDS KNOWLEGE IS CONTAINED IN PRINT FORM. IN THIS COMPUTER AGE, INFORMATION IS AVAILABLE AT YOUR FINGERTIPS. JUST THINK ABOUT THIS. CRANKCASE OIL DOESN'T WEAR OUT... IT GETS DIRTY... FROM CARBON. ITS A BYPRODUCT FROM BURNING AN AIR-FUEL MIXTURE. AGREE SO FAR?? DO YOU THING ALL 100% IS EXPELLED THRU THE EXHAUST?? IF THE ONLY SOURCE OF INTAKE AIR WAS THE CARBERATOR, AND IT HAD NO BREATER IN THE VALVE COVER FOR AIR INTAKE TO THE CRANKCASE.. IT WOULD NOT BE ABLE TO RUN???? PCV VALVES ARE ONLY AN EXIT. THEY HAVE A CHECK VALVE IN THEM THAT ONLY LETS GASSES GO ONE WAY... TO ESCAPE. HENCE THE NAME.. PCV.. POSITIVE CRANCASE VENTILATION. IF YOU COULD MAKE A MOTOR THAT RAN ON ITS OWN PRODUCED GASSES, THEY WOULD BE A PERPETUAL MOTION ENGINE & YOU'D BE A GILLIONARE. (PEOPLE HAVE BEEN TRYING TO FIGURE THAT ONE OUT SINCE BEFORE HENRY FORD WAS BORN) THE EXCESS GASSES ARE ROUTED THRU PCV VALVE TO THE AIR INTAKE (CARB) AS ONE OF THE FIRST ATTEMPTS AT POLLUTION CONTROL, & IT DOESN'T MATTER IF IT'S THRU THE AIR CLEANER, CARB, INTAKE MANIFOLD ECT. (G.M. MADE A TON OF VEHICALS WHERE THE PCV WAS VENTED IN THE AIR CLEANER) THE IDEA IS TO BURN ANY UNBURNT GASSES BACK THRU THE COMBUSTION CHAMBER (ONCE AGAIN) BEFORE BEING EXPELLED INTO THE ATMOSPHERE. BLOW BY OR OIL COMING OUT ANY V/C BREATHER IS A RESULT OF WORN PISTON RINGS AND FAULTY VALVES. PLEASE DON'T GIVE ADVICE TO PEOPLE THAT DON'T FULLY UNDERSTAND HOW THESE THINGS WORK & TRY TO PASS IT OFF AS FACTS. ALL YOU ARE DOING IS PERPETUATING YOUR OWN INCORRECT THEORYS ABOUT HOW THESE LITTLE PARTS WORK TOGETHER. BELIEVE ME G.M. HAS AN AWFUL LOT OF VERY SMART ENGINEERS WHO SPEND COUNTLESS HOURS DESIGHNING THESE THINGS, & IF THEY COULD SAVE 75 CENTS ON EVERY VEHICAL BY NOT IMPLIMENTING THESE IDEAS, THEY WOULD BE EVEN RICHER AND NOT BE IN NEED OF A FINANCIAL BAILOUT. ENOUGH FOR TODAY, AS I NEED TO GET ON MY OUTSIDE CHORES BEFORE IT GETS TO HOT OUT. DON'T BE TO HARD ON YOURSELF AS THERE IS A TON OF THINGS I DON'T FULLY UNDERSTAND, & THERES NO CRIME IN THAT. BUT PLEASE REFRAIN FROM GIVING OUT YOUR WELL MEANING BUT MIGUIDED OPINIONS AS COLD HARD FACTS. JOHN (PLEASE DONT TAKE ANY OFFENCE, OR THINK I'M TRYING TO BELITTLE YOU'RE TRUCK KNOWLEDGE OR COME OFF AS SOME KIND OF KNOW IT ALL, CAUSE I SURE DIDN'T MEAN IT THAT WAY. HONEST) JOHN

[piecesparts]

Originally Posted by junkyardjohn

PIECESPARTS-- I HAVE NEITHER THE TIME OR INCLINATION TO DEBATE OR EDUCATE YOU ON THE INNER WORKINGS OF AN INTERNAL COMBUSTION ENGINE. DO A LITTLE RESEARCH. ALL THE WORLDS KNOWLEGE IS CONTAINED IN PRINT FORM. IN THIS COMPUTER AGE, INFORMATION IS AVAILABLE AT YOUR FINGERTIPS. JUST THINK ABOUT THIS. CRANKCASE OIL DOESN'T WEAR OUT... IT GETS DIRTY... FROM CARBON. ITS A BYPRODUCT FROM BURNING AN AIR-FUEL MIXTURE. AGREE SO FAR?? DO YOU THING ALL 100% IS EXPELLED THRU THE EXHAUST?? IF THE ONLY SOURCE OF INTAKE AIR WAS THE CARBERATOR, AND IT HAD NO BREATER IN THE VALVE COVER FOR AIR INTAKE TO THE CRANKCASE.. IT WOULD NOT BE ABLE TO RUN???? PCV VALVES ARE ONLY AN EXIT. THEY HAVE A CHECK VALVE IN THEM THAT ONLY LETS GASSES GO ONE WAY... TO ESCAPE. HENCE THE NAME.. PCV.. POSITIVE CRANCASE VENTILATION. IF YOU COULD MAKE A MOTOR THAT RAN ON ITS OWN PRODUCED GASSES, THEY WOULD BE A PERPETUAL MOTION ENGINE & YOU'D BE A GILLIONARE. (PEOPLE HAVE BEEN TRYING TO FIGURE THAT ONE OUT SINCE BEFORE HENRY FORD WAS BORN) THE EXCESS GASSES ARE ROUTED THRU PCV VALVE TO THE AIR INTAKE (CARB) AS ONE OF THE FIRST ATTEMPTS AT POLLUTION CONTROL, & IT DOESN'T MATTER IF IT'S THRU THE AIR CLEANER, CARB, INTAKE MANIFOLD ECT. (G.M. MADE A TON OF VEHICALS WHERE THE PCV WAS VENTED IN THE AIR CLEANER) THE IDEA IS TO BURN ANY UNBURNT GASSES BACK THRU THE COMBUSTION CHAMBER (ONCE AGAIN) BEFORE BEING EXPELLED INTO THE ATMOSPHERE. BLOW BY OR OIL COMING OUT ANY V/C BREATHER IS A RESULT OF WORN PISTON RINGS AND FAULTY VALVES. PLEASE DON'T GIVE ADVICE TO PEOPLE THAT DON'T FULLY UNDERSTAND HOW THESE THINGS WORK & TRY TO PASS IT OFF AS FACTS. ALL YOU ARE DOING IS PERPETUATING YOUR OWN INCORRECT THEORYS ABOUT HOW THESE LITTLE PARTS WORK TOGETHER. BELIEVE ME G.M. HAS AN AWFUL LOT OF VERY SMART ENGINEERS WHO SPEND COUNTLESS HOURS DESIGHNING THESE THINGS, & IF THEY COULD SAVE 75 CENTS ON EVERY VEHICAL BY NOT IMPLIMENTING THESE IDEAS, THEY WOULD BE EVEN RICHER AND NOT BE IN NEED OF A FINANCIAL BAILOUT. ENOUGH FOR TODAY, AS I NEED TO GET ON MY OUTSIDE CHORES BEFORE IT GETS TO HOT OUT. DON'T BE TO HARD ON YOURSELF AS THERE IS A TON OF THINGS I DON'T FULLY UNDERSTAND, & THERES NO CRIME IN THAT. BUT PLEASE REFRAIN FROM GIVING OUT YOUR WELL MEANING BUT MIGUIDED OPINIONS AS COLD HARD FACTS. JOHN (PLEASE DONT TAKE ANY OFFENCE, OR THINK I'M TRYING TO BELITTLE YOU'RE TRUCK KNOWLEDGE OR COME OFF AS SOME KIND OF KNOW IT ALL, CAUSE I SURE DIDN'T MEAN IT THAT WAY. HONEST) JOHN

WOW. Not sure where this is coming from, but before this goes into the toilet with the moderators---I bow to your apparent superior knowledge. I just pointed out that the intake air is for combustion and YES the gases do slip by those nasty compression rings, but the whole thought process is to keep the crankcase purged with fresh air and in a negative pressure. sorry if I may have upset the world---I have built some engines in my time but may have missed something when I grew up on the farm.

Some would say that you are yelling at me, but I know that isn't the truth. NOW IS IT?

[El Jay]

I got an idea:
Let's all calm down before 72cheyenne350's thread gets locked through no doing of his own.

[junkyardjohn]

Originally Posted by piecesparts

WOW. Not sure where this is coming from, but before this goes into the toilet with the moderators---I bow to your apparent superior knowledge. I just pointed out that the intake air is for combustion and YES the gases do slip by those nasty compression rings, but the whole thought process is to keep the crankcase purged with fresh air and in a negative pressure. sorry if I may have upset the world---I have built some engines in my time but may have missed something when I grew up on the farm.

Some would say that you are yelling at me, but I know that isn't the truth. NOW IS IT?

SORRY FRANK.. I ALWAYS TYPE IN ALL CAPS. (LONG STORY) SOMETIMES WHEN I POST IT AUTOMATICALLY CHANGES TO LOWER CASE LETTERS & SOMETIMES IT DOESN'T. I WASN'T YELLING OR UPSET IN ANY WAY. LIKE I SAID IN THE PREVIOS POST..(I THOUGHT I MADE THAT PRETTY CLEAR BUT..) PLEASE DON'T TAKE ANY OFFENCE CAUSE I SURE DIDN'T MEEN IT THAT WAY. IT'S HARD TO TELL OVER A COMPUTER CAUSE YOU CAN'T SEE A PERSONS FACIAL EXPRESSIONS. I'M AN OLD FARM BOY TOO (READ THAT OLD HILLBILLY) & HAVE BUILT AT LEAST 50 OLD SMALLBLOCKS OVER THE LAST 40 OR S0 YEARS. SORRY IF I HURT YOUR FEELINGS AS THAT SURE WASN'T MY INTENT. ACTUALLY THIS WAS FOR ALL OF THE YOUNG FELLERS ON THIS SITE. THE ANSWER IS YES YOU DO HALF TO HAVE SOME FORM OF VENTILLATION ON THESE (OR ANY)OLD MOTORS. OTHERWISE THE INTERNAL PRESSURE WILL KEEP BUILDING, & EVENTIALLY FIND A WAY OUT. USSUALLY BY THE PATH OF LEAST RESISTANCE (EITHER AROUND BOLT THREADS OR THRU A GASKET. I DON'T MEAN TO SOUND LIKE A GRUFF OLD KNOW IT ALL B@STARD, I JUST FIND IT EASIER TO LEAD SOMEONE AROUND BY THE HAND UNTIL THEY COME UP WITH A SOLUTION OR ANSWER THERE OWN SELF. ONCE YOU UNDERSTAND HOW ALL THESE LITTLE PARTS WORK TOGETHER & FUNCTION.... THEY'RE SUPER SIMPLE. THATS WHY NONE OF MY VEHICALS ARE LESS THAN 25 YEARS OLD... EVEN I CAN UNDERSTAND THEM. JOHN

[Lee H]

Put a cheapo breather in each cover for now and research the correct PVC system for your application. The idea is to ventilate the case of blow by. Pair of breathers vent to atmosphere, PVC system vents back into the combustion chamber. Let's not make this any harder than it needs to be.

[Sinister]

I would definitely run a PCV valve. I had a 350 on which I ran just breathers. Turned the oil into a thick sludge.

[michael bustamante]

yeah 2 breathers is not a good Idea, you have to run a pcv to keep your oil from contamination and sludge build up,( not to mention keeping the engine somewhat clean) hook it up to the bottom inlet of the edelbrock, Ive seen set ups where they hook it up to the air inlet at the back of the carb coming out the intake also but I dont think thats a very good idea, also If you think about it, clean out the pcv once in a while.

[HuggerCST]

Originally Posted by junkyardjohn

( MOST MOTORS ONLY HAVE A PVC VALVE OR A BREATHER. NOT BOTH. IT'S AN EXIT. THE MOTOR GETS PLENTY OF AIR TO BREATH RIGHT THRU THE CARB.)

I'd have to disagree here also, John. Most engines that I've worked on have both a PCV valve and a breather (or pull fresh air through the air filter), and the only way that a PCV can pull air through the carb is to get it past the rings. So if you have a PCV valve with nothing for a breather, then it will put the crankcase under full vacuum. You can run a engine with a breather only, it will just push the excess crankcase vapors out through it, like the old draft tubes did. Here is a good link to explain the PCV system. http://www.aa1car.com/library/pcv.htm

[junkyardjohn]

Originally Posted by HuggerCST

I'd have to disagree here also, John. Most engines that I've worked on have both a PCV valve and a breather (or pull fresh air through the air filter), and the only way that a PCV can pull air through the carb is to get it past the rings. So if you have a PCV valve with nothing for a breather, then it will put the crankcase under full vacuum. You can run a engine with a breather only, it will just push the excess crankcase vapors out through it, like the old draft tubes did. Here is a good link to explain the PCV system. http://www.aa1car.com/library/pcv.htm

I THINK WE HAVE SOME MISCOMUNICATION. I AGREE 100% WITH THAT ARTICAL. (EXCELLANT EXPLAINATION OF HOW IT WORKS) A WORKING PVC VALVE WILL NEVER PULL ANY AIR FROM ANYWHERE. IT'S A ONE WAY EXIT. MOST ALL THE ENGINES FROM THIS ERA HAD A PCV VALVE (STATE OF THE ART ANTI-POLLUTION DEVICE AT THE TIME) ON THE RIGHT V/C & A SOLID NON-VENTED FILL CAP ON THE LEFT V/C. AND THE PVC VALVE WAS VENTED INTO THE AIR CLEANER. I THINK IT EXPLAINS IT IN THAT ARTICAL. THE NEWER ONES MAY BE DIFFERENT, I COULDN'T SAY CAUSE ANY CAR OR TRUCK AFTER ABOUT 1980 IS PRETTY WELL INVISABLE TO ME. JOHN (THAT ARTICAL IS EXZACTLY WHAT I WAS TRYING TO SAY)

[HuggerCST]

Originally Posted by junkyardjohn

A WORKING PVC VALVE WILL NEVER PULL ANY AIR FROM ANYWHERE. IT'S A ONE WAY EXIT. MOST ALL THE ENGINES FROM THIS ERA HAD A PCV VALVE (STATE OF THE ART ANTI-POLLUTION DEVICE AT THE TIME) ON THE RIGHT V/C & A SOLID NON-VENTED FILL CAP ON THE LEFT V/C. AND THE PVC VALVE WAS VENTED INTO THE AIR CLEANER.

Maybe I'm misunderstanding (wouldn't be the first time), but working PCV valves aren't "vented", but are hooked to manifold vacuum. The PCV valve controls the vacuum, and pulls air/vapors out of the crankcase.(through the air cleaner and tube, through the right valve cover (on a stock '67-'72 V-8), through the crankcase to the PCV valve in the left valve cover) These engines did have a non vented oil cap, but also had a vent tube between the right valve cover & air cleaner.