At the PRI show I met a guy who is manufacturing Pontiac Ram Air V parts. As some of you may know, that engine is a close cousin to a 427 Tunnel Port, and in fact I was told at the show that after Ford cancelled the tunnel port program, a bunch of the engineers at Ford who worked on it went to Pontiac and were instrumental in developing the Ram Air V. Anyway, the topic has come up in the past about whether one of these Ram Air V intakes could be made to work on a tunnel port engine, using my tunnel port intake adapter. The guy at the show is based in Indianapolis and was kind enough to bring me one of his single 4 barrel intakes, and let me take it home to check this out.
Over the new year's weekend I finally got a chance to look at this. I have one tunnel port intake adapter that is a defect and not usable, because a big end mill came loose during the milling operation and gouged one side of the intake adapter pretty good. But the intake adapter's basic dimensions were intact, so it was a good candidate for checking to see if this intake would be made to work with the adapter. One thing that was clear at the show was that the adapter's mounting surfaces would have to be machined down, a lot, to have a chance for success at this. Also, it looked like the Ram Air V manifold's mating surfaces would have to be machined as well.
Measurements I took over the past couple days showed that I needed to machine the maximum amount off the surfaces of the intake adapter. So, I took 0.800" off each manifold mounting surface of the adapter so I could see where we were after that. Here's a picture of this defective adapter, with the manifold mounting surfaces machined:
Of course if I went forward with something like this it would not look so rough, but I needed to machine it this way to see what the problems might be. I was able to confirm that there was enough material in the intake adapter to allow me to counterbore a hole for the bolts that go into the cylinder head, although special low-head capscrews would probably be required. One area of concern is the gasket area above the ports; there is only about 0.175" there and I'd feel better if there was more like 0.250". But at this point, it looked do-able.
Here are a couple pictures of the Ram Air V intake. You can see how much like a tunnel port it is:
Finally, the picture below shows the intake sitting on the intake adapter:
As I had determined at the show, in this position the manifold does not fit far enough down on the intake adapter; the port openings are actually above the valve cover rail. The flange of the intake is a little over 0.500" thick, and to make the roof of the ports line up between the intake adapter and the manifold, the flange of the manifold would have to be cut about another 0.325", leaving a flange thickness of only 3/16" or so. But I think that would be OK; I've seen flanges thinner than that before. The other issue is the port alignment, which is pretty close but would require either some porting on the intake manifold, or a new port program for the intake adapter to shrink the ports down so that they would match up with the Ram Air V manifold ports.
What do you guys think of this combination? Would it be worth pursuing? I don't know what the market is like for the single 4 tunnel port intake manifolds, but it seems like you could get one for less than you'd have into one of my adapters plus this Ram Air V intake with the requisite machining ($779 for the TP intake adapter and ~$700 for the manifold, plus $85 to machine the flanges so it would fit). You'd also have to make custom intake gaskets, because there's no room for an O-ring seal between the ports of the intake adapter and the manifold. But if you really wanted to do it, you could...
Any comments welcome - Jay
