I’m about to replace the stock intake on my 390 with a Performer RPM and have a question on how to deal with the PVC vacuum lines. As you know on a stock 390 the line coming out of the PVC valve splits with one side going to a vacuum port at the front of the manifold and one going to a port at the back of the manifold. The new intake does not have a port to route to at the back, only at the front.
Everything I can find online notes that the manifold has “provision for adding the PCV” but I cannot find anything, after hours of searching, that details how this is done.
Do I need to drill and tap the rear runner to add a port in the same location as on the stock manifold? Or can I ignore this and just run to the front port? I assume that I shouldn’t tie into the port at the base of the carb at the back where the power steering vacuum ties in.
Hopefully this question makes sense and is not “too” stupid.
Is the Performer a single plane or dual? The Ford manifold fittings splits the PCV smoke equally between the two planes and gives a balanced vacuum to the power brakes. If the Performer is single plane then the one front port would give you full vacuum.
I put one on a friend’s 428. We ran a PCV hose from the PCV port on the Holley 3310 to the PCV valve. Works great. You could drill and tap the plenum below the carburetor, but chances are you won’t need to if the carburetor already has a PCV port like most aftermarket carbs do.
Yes sorry, meant power brakes not power steering.
Existing carb is an Edlebrock, but I am replacing it with a new Holley 750 vacuum advance that I bought a couple of years ago and have not yet installed. Can’t remember the part number, but I believe there is a vacuum port at the back. Will check tonight when I get home.
Well, stuff got in the way and the new manifold did not get installed for the summer, but well underway now. I “think” I have the vacuum figured out but have a couple of new questions.
The Performer RPM intake does not have a heat crossover passage while the stock GT heads do have the ports. Do I just install the gaskets and intake as is, or do I need to do anything special at the crossover ports on the heads? I’m using the recommended Fel-Pro 1247 gaskets.
The new intake does not allow for the locator dowel in of the front of the block and I’m having a bitch of a time getting the dowel out. Tried repeated soakings with PB Blaster and vice grips, gripped by a second pair of vice grips to hammer on, and it does not want to budge. Is there a simple way that does not involve buying an expensive dowel removal kit for getting it out? Or just grind it off flush?
As for the dowel, you can either mask off and grind it flush (preferred), vacuuming up the shavings, or drill a 1/4" hole in the intake end gasket flange to accept it. In any case take care that no shavings get into the engine.
I used a little heat and a vice grip slide hammer. Mine was home built by welding a nut on the jaws of the vice grips or you can buy one like this… Good tool to have around either way
Thanks for the replies. I’ve been using vice grips and a hammer but so far have just managed to groove the dowel. I’ll try some heat as well but if that doesn’t work I guess I’ll just grind it off.
Any thoughts on blocking thereat crossover? Saw a video on roadkill where they suggested putting a piece of flattened beer can over the port, but that sounds kind of dodgy to me. The gaskets I got do not have an opening for the ports, so would I be safe in just using them, and the non ported intake to block the ports? Did searches on a number of sites and couldn’t find any info on how other people have dealt with this or what they would recommend.
the Roadkill guys do most of their driving in Southern California or in the desert of California. You on the other hand live in BC. There is a good reason for the heat crossover to be there. You need it, they don’t.
Hi Royce. I don’t drive the cougar between around October and May so driving in cooler weather shouldn’t be an issue. Regardless the Performer RPM intake has no provision for the crossover, so keeping it isn’t an option. I just want to make sure that I don’t cause damage to the intake or gaskets by blocking the ports in the heads. If just installing gaskets and intake right over top of the ports is fine, great, if not I’m looking for some advice on how or if the ports should be otherwise blocked.
just installing gaskets and intake right over top of the ports is fine.
Yes, that’s fine. Just install the gasket over the blocked exhaust cross over port.
It will be more “cold blood” on start up until you get some heat into the motor with the absence of the exh cross over port. But, on the plus side less heat issues on hot days at the carb as you don’t have the hot exhaust port anymore.
