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Old 07-27-2007, 02:38 PM
406 ss monte's Avatar
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do you have to run a pvc valve?

i have a 85 ford truck with a carbed 302, & the valve covers are off a 91 f.i. 302. they don't have a place for a PVC valve. would it hurt to run a vacuum line to the port on the oil fill neck? can a PVC valve be run side ways or do they have to sit strait up?

thanks all.

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Old 07-27-2007, 03:10 PM
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PCV realy needs to run staight up but it will work sideways. It'll just fill up with oil faster.(and posibly spray oil into the carb) The PCV is just a check valve that keeps oil and carbon from entering the carb....in theory....it works better than nothing. If you are not going to run a PCV valve the you will most likely spring oil leaks and have a problem with the motor wanting a healthy appitite of oil which is never good

Also something to think about is that a dodge neon has an INLINE pcv valve
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Old 07-27-2007, 03:25 PM
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The crankcase has to be vented one way or another. If it isn't pressure will build up in the crankcase and will cause all kinds of oil leaks.

You can use a PCV valve, valve cover breathers, or the old road draft tube to do this. The environmentally correct way is the PCV valve because it directs the vapors into the carb and they are burned during the combustion process rather than adding pollution to the air.

If you're using stamped steel valve covers it's not a big job to drill a hole to mount a PCV valve. Just remember you have to vent it somehow.
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Old 07-27-2007, 03:29 PM
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Quote:
Originally Posted by 406 ss monte

i have a 85 ford truck with a carbed 302, & the valve covers are off a 91 f.i. 302. they don't have a place for a PVC valve. would it hurt to run a vacuum line to the port on the oil fill neck? can a PVC valve be run side ways or do they have to sit strait up?
Doesn't the later F.I. covers have a fill cap(s)? If so, you should be able to fit a special grommet into one opening for the valve. Fresh air for the system should be drawn from the air cleaner.

The valve can be in any position as it is only a metered orifice and anti-backfire valve for the system.
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Old 07-27-2007, 03:31 PM
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Quote:
Originally Posted by 406 ss monte
i have a 85 ford truck with a carbed 302, & the valve covers are off a 91 f.i. 302. they don't have a place for a PVC valve. would it hurt to run a vacuum line to the port on the oil fill neck? can a PVC valve be run side ways or do they have to sit strait up?

thanks all.
It's usually considered better to tap from the rocker cover, just to insure air flow through that area, but it isn't absolutely necessary you tap from there. Off the intake's valley cover or from an oil filler pipe have all been used by somebody at one time or another.

I'll admit that I really don't know how direction sensitive these things are but there are in-line PCV valves at the parts store designed for use on their side. The application (brand of car) really doesn't matter just pick one for a similar configured engine. Any year 289, 302, 351 will work just fine even one from an FE block as long as the cam is about the same specs as your 302's.
A similar Chevy valve for a small block will also work. The cam specs do much to establish the intake vacuum, the PCV is loosely calibrated around a certain amount of vacuum being present. So anybody's V8 valve for an engine with mild specs is fine. PCV valves for older late 60s and early 70's high performance engines with long duration, high overlap cams may be unsuitable because they are designed to operate with lower vacuums which in your engine could have them open too far too much of the time.

You also need a fresh air source, this is usually a tube from the air-cleaner to a valve cover. A breather tube that is both drawing fresh air and venting the PCV may not prove to be effective in getting clean air into the crankcase and blow-by out. Clean air going into the PCV would react like a vacuum leak and lean the mixture. Blow-by is mostly unburnt mixture which when drawn into the intake is bringing fuel with it so it doesn't tend to lean out the incoming mixture.

The pick up point also needs to shield oil from being drawn into the engine, this would reduce the octane rating of the mixture and make the engine detonation prone. It would also increase oil consumption.

Frankly I go back to the appropriate rocker covers for the engine.

Bogie
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Old 07-27-2007, 03:47 PM
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PCV valves do so much more than just vent crankcase pressure, they actively remove contaminants from the oil. If you don't run one I highly doubt your oil will last more than about 1000 miles before turning into corrosive goo.
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Old 07-27-2007, 04:09 PM
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why can't i hook a pvc valve up to the line on the filler tube?

why can't i run the vacuum line that should go to a pvc valve to the line on the filler tube without a pvc valve? it would have full engine vacuum.

my valve covers i have are like the ones pictured but they are steel instead of aluminum, & are very low profile. a pvc valve would hit the rockers if i just tried to drill a hole to put one in.

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Old 07-27-2007, 04:27 PM
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Quote:
Originally Posted by 406 ss monte
why can't i hook a pvc valve up to the line on the filler tube?

why can't i run the vacuum line that should go to a pvc valve to the line on the filler tube without a pvc valve? it would have full engine vacuum.

my valve covers i have are like the ones pictured but they are steel instead of aluminum, & are very low profile. a pvc valve would hit the rockers if i just tried to drill a hole to put one in.

You can, especially if the oil cap seals the filler tube so outside air doesn't get in. You do want to protect the end of the tube or a fitting in the filler so oil can't be spilt into the PCV tube. This can be a simple as making sure you use a funnel when adding oil and mount the PCV valve so it's higher than the tap at the oil filler tube with it's intake side slightly lower than the outlet so any liquid oil getting in there will run back into the engine. After the valve any shape that gets to an manifold vacuum source will be fine.

Bogie
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Old 07-27-2007, 04:40 PM
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Late Ford 302 / 5.0 have the PCV in the lower intake. Here is a Q&A forum detailing where to look.

http://en.allexperts.com/q/Ford-Repa...nd-Marquis.htm
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Old 07-27-2007, 04:53 PM
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This style won't work without a lot of fabrication;



This is an early system that has the PCV valve mounted in the lower plenum. The hose you see on these covers is the fresh air intake for the system.

You would have to drill the blanc cover to accept a valve and then source it to manifold vacuum and connect the oil fill tube hose to a fresh air source (preferably the air cleaner on a carbureted application).
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