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Explorer valve cover vacuum issues

hunter1

Contributor
Jr. Member
Joined
Feb 2, 2013
Messages
334
Loc.
Maryville, Tn
351W with Explorer front dress and valve covers. I ran a hose from the barb on the filler neck to the center port on a 1406 Edlebrock carb. I noticed when I shut the engine off, I could hear a hissing sound coming from the carb throat. I started it back and unscrewed the filler cap on the valve cover and the engine died. Got my remote starter and with the cap off the filler neck I tried to start the engine, would not start. I then placed my hand over the filler neck and the engine started and was pulling a lot of vacuum against the palm of my hand. Should I put an inline PVC valve or some sort of orifice in the hose? Should I vent the other valve cover?
 

DirtDonk

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Nov 3, 2003
Messages
48,738
You’ve got it hooked up backwards. Well, not backwards actually. You’ve only got half of it connected.
You do not put the oil filler fitting directly to vacuum. That goes to a filtered a source. Only the PCV valve goes to vacuum.
Since you have a carburetor, you don’t have the explorer manifold with the PCV port in the back. You need a separate port for a PCV valve.
Usually, with a carburetor, that’s a valve cover, but not in your case.
You’re gonna have to create one. The PCV system is a loop. Clean air in, dirty air out.
 

DirtDonk

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Should I put an inline PVC valve or some sort of orifice in the hose? Should I vent the other valve cover?
These are all options. You need at least two of them for the system to work.
The vacuum should be metered, either through an orifice or a calibrated valve.
The air return should be in a valve cover, most likely.
Either in the fitting that you have connected to the carburetor right now, instead of to the carburetor. Or in a port, you create in the other valve cover.
 

Oldtimer

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Jr. Member with Sr. moments
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Feb 4, 2005
Messages
1,094
Loc.
Sunnyvale, CA
And once the PCV system is plumbed, you need to adjust carburetor mixture screws & idle speed and set initial timing, with the calibrated (pcv) vacuum leak.
 
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