Could I run pcv of the intake manifold instead of the carb ?

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Hey guys quick question . Could I run the pcv of the back port on my intake manifold instead of the carb ???
 

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Dammit picture is flipped , sorry . But yeah could I run the pcv to that 90 degree fitting thst I have on the back of the intake manifold instead of the carb ???

Thank you
Peter
 
You can but I wouldn't. Any blow by will dilute the mixture on the cylinder that port goes to. At the base of the carb the pcv output is diluted across all cylinders.
 
^^^ What he said. The manifold ports are for dedicated vacuum supply to brake booster etc... and will not bode well for calibrated vacuum leaks drawing in crank case vapors.
 
Ok guys I will not run it off that port and run it off the carb . Thanks you so much
 
The rear cylinders will tend to run lean at idle and light tip-in, and that makes it a bear to tune.If you flip the carb over you will see how the carb manufacturer handles the problem.
 
Unless he has one of those rare carbs without the PVC for Fords....
 
Can't you just run it to nowhere? I mean isn't the PCV just to release crankcase vapors? Can't it vent to the atmosphere? Of course it's bad for the air, but I live in iowa so I don't care that much haha.
 
alpha13 said:
Can't you just run it to nowhere? I mean isn't the PCV just to release crankcase vapors? Can't it vent to the atmosphere? Of course it's bad for the air, but I live in iowa so I don't care that much haha.
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a lot of intakes have a 3/8" port in the rear of the plenum that can be used. ever thot about drilling and tapping for a hole in front and back? u could tee the pcv line so it would run to both, for more equalization of the venting. I have to pull my intake to reverse some oil mods. I did anyway, so I`m going to take a long look at the front and rear thing.
 
my 950hp has no vac port and I run my pcv in the manifold port seems to work great.
I may put a vac port in my 2 inch spacer in the future .
 
alpha13 said:
Can't you just run it to nowhere? I mean isn't the PCV just to release crankcase vapors? Can't it vent to the atmosphere? Of course it's bad for the air, but I live in iowa so I don't care that much haha.
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Many race engines don't use pcv's. That's why you see multiple valve cover breathers. You have to release the internal pressure somehow. The drag racers use a vac-u-pan system where the fumes are sucked out by a tube in the collector in the header. Years ago before Federal Emissions rules there was a downdraft tube that would suck the fumes out as the car goes down the road. Another venturi effect system.
 
Norway-dart said:
its free hp to get as low as possible pressure inside the engine:)
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And internal pressures cause seals and gaskets to blow out. That's why every engine, transmission, and rear axle has a vent.
 
There are also high dollar belt driven and electric evacuation pumps used on race engines. Good as mentioned for leak prevention but also extra ponies with the negative pressure.
 
toolmanmike said:
And internal pressures cause seals and gaskets to blow out. That's why every engine, transmission, and rear axle has a vent.
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Not TOTALLY true (I'm being pedantic...), my '53 Buick doesn't have any rear axle vent.

I figured this out after I had it rebuilt and it blew out the pumpkin gasket. Apparently, the old seals were felt, and they must have let enough pressure by that Buick got by without a vent. I am now running a vent tube through a brake bleeder screwed into one of the back cover bolt holes (which is open). I put an inline fuel filter at the end and now it's vented.

Just thought I'd share a weird story...carry on! :)
 
alpha13 said:
Can't you just run it to nowhere? I mean isn't the PCV just to release crankcase vapors? Can't it vent to the atmosphere? Of course it's bad for the air, but I live in iowa so I don't care that much haha.
Click to expand...
As said, you are just asking for oil leaks and oil in the wrong places (like down the intake valve guides).
 
I have read on certain engines a vac system can be worth an additional 30 Hp.......
 
Most engines benefit because it helps ring seal even on plain pistons. But that doesn't mean it's great technology for your street car. They tend to wear out quickly when you put them in an environment like a street car.

You can run the PCV off the manifold - but it has to be from the plenum area, and if it's possible, you're better off putting it into a spacer or something that pushes it as far from any individual port as you can for the reasons noted.
 
And make sure you run a complete PCV system. You should have a tube from the other Valve cover ran to a port on your air cleaner. No Valve cover breathers.
 
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