Those who follow such things will tell you that the best designs not only perform well, but that they just flat look good too. There are certain designs that will always be timeless, like the near-perfect form of a P-51 Mustang warbird or the shape of a 1955 Chevy taillight. Such a case could be made for the cross-ram manifold. The idea was simple enough. It's really nothing more than a horizontal tunnel ram. There are plenty of early examples of the tunnel ram. The Chrysler-bred Ramchargers designed a crude but effective tunnel ram out of lengths of rubber hoses fitted to a large box on top of which was bolted a couple of carburetors.
But it wasn't until the mid-1960s when that idea finally caught hold. In 1966, Trans-Am took off and suddenly short stroke 302ci small-block Chevys were in need of eight barrels worth of air and fuel. But these little motors also needed torque to pull them off the corners and that demanded intake manifold runner length. The current eight-barrel intake manifolds lacked runner length, so an enterprising engineer, probably in the employ of General Motors, created the cross-ram manifold. All he did was lay the runners down across the top of the manifold so that the added length didn't pop through the hood. With that elegant solution, generations of hot rodders were entranced with the idea.
That lust for an exotic eight-barrel induction has never really gone away. Combine this with a better understanding of engine tuning and the effects of a pair of big carburetors on a small displacement engine and we have circled back to resurrect an old-yet-new Offenhauser manifold on our 1955 Gasser project. (As luck would have it an Offy manifold base (PN 5893), a manifold top (PN 5903), and the appropriate linkage kit (PN 5902) were waiting for us on a back shelf. You can still order these part numbers from Offy but they may be on back order.) Form demands that we not place a mundane single four-barrel on such an aggressive nose-high Gasser so the cross ram seemed a natural, if for no other reason than Gassers never came with such an animal. But function demands that beyond killer looks our eight-barrel adventure must also work. So that became our quest and the not-small effort that ensued.
Street Rodder Editor Brian Brennan wanted one of Offenhauser's cross rams to put on top of his retro 327 small-block being installed in the 1955. Ironically, among the dusty piles of tooling in Offy's backroom were the exact pieces necessary to produce one of these discontinued manifolds. The die was, ahem, cast and the result is what you see here. But that was just the beginning. Most rodders would be content to add a couple of early Holley four-barrels or perhaps even a pair of early Carter carburetors, but while this is a classic retro ride, there aren't any rules that we had to follow the norm. The best way to add a little 21st century flash was to integrate a pair of electronic throttle bodies using FAST's EZ-EFI system. Usually the FAST system is designed to operate with just one four-barrel throttle body, but FAST offers a system with a piggyback harness to connect to the second slave throttle body with injectors only. This adds a wire harnesses to the top of the manifold but that was relatively easy to disguise to maintain the look of a typical 1960s Gasser induction. We added a retro-looking fuel line and some slick throttle linkage pieces and we were in business. Follow along as we chronicle the crossover of a 1960s manifold into a current piece of fuel injection technology. Don't forget to stay tuned for the buildup of our Retro-Tech 327, which will grace the pages of this magazine in the next couple of months. We will once again be combining both old and new technology in our 327 Gasser motor. Who says you can't teach an old dog a few new tricks?
Since we were building a manifold similar to a small-block Trans-Am 302 cross ram, we decided to take a cue from the factory with a custom air cleaner instead of a pair of simple 6-inch air filters. The factory used an oval air cleaner assembly to cover both carburetors that looks retro, so we took that idea one step further with a custom billet lid with fins to match the PML valve covers. We started with a 21x10-inch template that we took to our pals at CAD/CAM Consulting in Newbury Park, California. Pete Jorgensen used a picture of the original GM filter assembly to create this slick, finned version of a Trans-Am air cleaner assembly. We are still working on some of the cool design factors so you will only get several small glimpses of it now. Make sure to tune in when we unveil our Retro-Tech 327 in an upcoming issue, you won't be disappointed.
A custom air cleaner housing isn't much good without a matching air filter. While we could have built the filter around an existing filter element, that takes all the fun out of having a custom filter. What we discovered is that K&N will build a custom air filter element for anyone if you have filter dimensions for your application. We followed along as K&N built two filter assemblies for our EZ-EFI–equipped cross ram.