I've got a 300 in an 84 F150. My PVC Valve has 2 connections. I know the large one goes to the base of the carb. Where does the second one go.

 

Dunno...You'd need to find a vacuum hose chart. But you shouldn't really need the extra hose for the PCV system to work. I'd plug it until you can find out where it goes. As long as the one to the intake is connected, and the valve functions, it should work.
MK

 

I replaced mine because it also had those 2 connections, one capped and one went to the valve cover (351w) ... I was thinking it was an aftermarket job so I pulled it out.

So I bought one from the Ford dealer and guess what -same thing, 2 connections but there was rubber cap included to seal off one of the ports.

I just re-installed using the same configuration as the one I pulled out... beats me why they come like that unless the ports are of different sizes for different applications.

My Haynes manual did not shed any light on this, so I re-installed it using the same configuration as the old one.

 

after way too many years of working on ford industrial 300's, I can answer this question. Ford in their infinate wisdom used the same pvc valve for multiple applications. The top port is used for some emission control operations, for those other uses the top port is simply blocked off. hope this helps

 

Thanks for the input oldschool63! Its been bugging me for months about thoses 2 ports. Do you know which vehicles might have used both or the other port, or why?

Funny that Haynes does not mention this - unless I've missed it.

mrstace84 - there are some other threads regarding PCV and re-routing the intake FROM cyl 8 TO the vacuum plenum (tree) to avoid fouling.. sorry I don't have the info handy but will post later if needed.

Not sure if it applies to your 84 truck though ..mine's a 1989.

-rlp

 

Sorry mrstace84 .. just realized mine's a V8 and yours is probably a 6 (300), so don't know about that re-routing.

 

sorry it took so long to reply. As for that upper port being used, it all depended on where the truck was built for and what type of emissions it had. I've seen the same year and model with different routings and for no real reason i could determine other than the emission package it was sold with. Or it could just be a Ford thing! : )

 

on my 84 inline six, the top connection has a hose to the carb base, and the bottom is simply plugged off...that's all i've ever actually noticed w/ the pcv valves on the inline six's i've had.

MontanaFord