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Crankcase Venting

NV_K5

NV_K5

1/2 ton status
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I have a new PCV valve connected to my intake via the carb plate.

I have an open bolt hole behind the fuel pump that when plugged with a short 3/8's bolt the motor loads up and runs like crap. If I remove the dipstick from the tube with the bolt installed it whistles but runs as good as withouth the bolt = better.

Any suggestions - I'd rather not leave a sucking hole direclty to my crankcase.

Venthole.jpg
 
You need a short bolt in that hole since it intersects the fuel pump pushrod and will leak oil without one being there. You should have a PCV valve in one valve cover going to the carb/TBI and a breather tube from the opposite valve cover to the bottom of the air cleaner to make the system work properly.
 
That's the issue I'm really getting at, the motor has never had a "breather" on the valve covers etc. The M/T covers put on by the po only had the holes punched on one cover for a fill (standard cap type) and a pcv. I guess I got all the leaks fixed (although it doesn't look like it in that picture) and now it whistles.

4x4High - I guess I'll pull the other cover and punch the oposite corner for a push-in breather.

thanks guys.
 
NV_K5 said:
That's the issue I'm really getting at, the motor has never had a "breather" on the valve covers etc. The M/T covers put on by the po only had the holes punched on one cover for a fill (standard cap type) and a pcv. I guess I got all the leaks fixed (although it doesn't look like it in that picture) and now it whistles.

4x4High - I guess I'll pull the other cover and punch the oposite corner for a push-in breather.

thanks guys.
Click to expand...

The "breather" needs to be a hose that connects to the base of the air cleaner otherwise it will be a vacuum leak.
 
I've seen some photos in magazine articles recently where the valvecover breather is actually plumbed with a long tube down into the header collector....

What's that all about? :dunno:


:usaflag:
 
Greg72 said:
I've seen some photos in magazine articles recently where the valvecover breather is actually plumbed with a long tube down into the header collector....

What's that all about? :dunno:


:usaflag:
Click to expand...

EVAC system

I'm putting one on our race car soon
 
Those are evac systems and don't use a PCV valve. You will find that on alot of race cars. Basically the vacuum created from the exhaust moving past a one way valve threaded into the header collector pulls the fumes/vapors out of the crankcase. That system is very effective at removing fumes/vapors from the crankcase as long as the vehicle has alot of RPM's to create a good vacuum across the valve.
 
4X4HIGH said:
Those are evac systems and don't use a PCV valve. You will find that on alot of race cars. Basically the vacuum created from the exhaust moving past a one way valve threaded into the header collector pulls the fumes/vapors out of the crankcase. That system is very effective at removing fumes/vapors from the crankcase as long as the vehicle has alot of RPM's to create a good vacuum across the valve.
Click to expand...


Good lord 4X4HIGH!!! I read a lot of threads on CK5; what don't you know about???:bow::bow::bow::D
Hoby
 
4X4HIGH said:
Those are evac systems and don't use a PCV valve. You will find that on alot of race cars. Basically the vacuum created from the exhaust moving past a one way valve threaded into the header collector pulls the fumes/vapors out of the crankcase. That system is very effective at removing fumes/vapors from the crankcase as long as the vehicle has alot of RPM's to create a good vacuum across the valve.
Click to expand...

Those use something kind of similar to a pcv, the smog valves to prevent the exhaust from pressuring the crank case
 
Does the breather have to be in the the air cleaner? What about aftermarket push in type filters. What am I missing?

Also, that bolt hole can vomit oil. Usually at higher RPM's. Covers the engine compartment and doesnt leak when your trying to find it:mad:
 
Kenny78 said:
Does the breather have to be in the the air cleaner? What about aftermarket push in type filters. What am I missing?

Also, that bolt hole can vomit oil. Usually at higher RPM's. Covers the engine compartment and doesnt leak when your trying to find it:mad:
Click to expand...

Yes the breather tube needs to be in the air cleaner. If you just use a push in style breather that is open to the outside air it is a vacuum leak. The system needs to be a closed system which is just how i explained it above.

The valve used with an evac system is nothing more than a one way smog pump valve to prevent exhaust gases from going into the crankcase.
 
Not that it hasnt been said before, but thanks for the knowledge. I am still using the cheap open air element whatever, until I can find a filter housing/intake that I like. Since I have you on the line, a properly sized pipe intake works the same on a carbed engine? If so, what size pipe is sufficient for a stock to mild SBC. Thanks again 4X4HIGH
 
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