I have a 1964 Ford Fairlane with a rebuilt early 80s 302 with cam and four barrel 600cf Edelbrock Performer carb. Anyway, I had it out yesterday and it ran fantastic. Today, I decided to install the new valve covers I got for Christmas (My wife is great! lol). There was one difference between the valve covers I had, and the ones I installed. The oil filler side of the old covers had a screw down oil cap/breather with a PCV valve which connected to the carb. The new valve covers have an extended tube for the oil filler which requires a push in cap. The opposite cover has a simple breather elbow that connects to the air cleaner just like the old one did. I purchased a breather style cap with a hose nipple for a closed ventilation system. The cap took a 5/8 hose which doesn't fit the carb nipple, so to make it work, I inserted a piece of the old PCV valve to carb hose into the new 5/8 hose to make the connection. (Please see pictures to see the old and new set up). Long story short, it's not running very well. I have tried plugging the hose out of the carb and it makes some difference but not a whole lot. I am reasonably sure that the new valve covers are mounted and sealed properly. My questions are: 1) Can/should I run a PCV valve with this set up, if so, how? I am not certain that they make a "push in" cap with a PCV outlet tube that will fit these covers although I know you can get an "inline" PCV that might work. 2) I know these Scott Drake valve covers are quite common and I can't possibly be the first person to run into this situation, so how should I set this up so that it's done properly. The old set up was breather elbow to air cleaner on one side and closed cap with PCV to carb on the other. 3) Why are things running so crappy now considering it was running fantastic when I parked it last night before the valve cover change? All I did is change the covers, put in a new elbow on the one side to connect to the air filter, and a "push in" breather (without PCV) run to the carb on the other. I think the pictures might help make more sense of it than I explained, but any help or advice would be greatly appreciated. Thanks in advance for your help!
The early type valve covers that you have were set up different. To make it work, pop that PVC valve out of the late fill cap and install it in the valve cover with the grommet. Then connect that to the carb. The problem is the Edelbrock carb has this connection on the front of it (so routing the hose is a PIA), while the OEM connection was to a spacer under the carb at the rear, or the rear of most aftermarket Holley carbs. The hose connection on the fill cap vents to the air cleaner base (which is why it's too large for the PVC), although most early motors just used a vented cap and had no hose. Another reason I don't like Edelbrock carbs on Fords..... they just aren't set up right for a Ford. The existing set up you took off was late-model only.
It's running badly because you've given yourself a vacuum leak. The filler side (driver's side) cover should not be plumbed to engine vacuum. It should be plumbed to fresh air. The passenger side is for the PCV valve which gets plumbed to engine vacuum.
It will run right if you put a PCV in the line that goes to bottom of the carb. That meters how much air is pulled from the crankcase into the carb and burned. Without the PCV you have a GIANT vacuum leak.
PCV has to have an inlet and an outlet to work properly, otherwise you are sucking air out of both sides which will never work. What you've done is suck out of both sides, with the driver's side lacking a valve, so it's basically a total-loss of vacuum. Your old system and the newer system are mirror-image opposites, switching the PCV valve from the driver's side to the passenger side. That's it. Plug the front carb port and run the rear carb port to the passenger side cover with the pcv valve. The driver's side cover remains open to the air, with a filter cap on it.
Steve, the Edelbrocks have a threaded port on the back side of the carb base and it works fine for the PCV. Edelbrock calls the front port the PCV port and the rear one the Power Brake port, BUT I've run MANY, MANY Fords that way. Edlebrocks are all I use and never have a problem on Fords. Edelbrock claims that you should use the front port as that is on the primary side of the carb, but both port have the same full vacuum so it doesn't seem to make and difference in the real world. It also doesn't make any difference which side the PCV valve goes on so you can put it in the drivers side front valve cover hole and go to the front port on the carb if you want and simplify the hose routing.
I want to thank everyone for being so helpful. It's things like this that make being a car enthusiast so rewarding. Having people with knowledge and experience willing to contribute, makes it both fun a rewarding. Problem solved! I switched the PCV to the passenger side and vented the filler cap/breather on the drivers side to the air cleaner. It's back to it's badass self. I am probably going to reconfigure the setup so that I don't have a hose reaching from the back of the passenger valve cover PCV to the front of the carb, but at least she's up and running. Thanks again, you folks make it all worth while!
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