Hot rodding has always been built on Moore’s Law — “More is better, too much is just right.” And with that in mind, what could be more “More” than multiple carburetors? Variations of that configuration have been a staple of racing and high-performance cars for at least a century.
Multiple carburetor setups arguably reached their zenith in the mid 1960s, with the introduction of the tunnel-ram intake manifold. Built specifically for drag racing, the tunnel ram was designed entirely for high-rpm use. These giant intakes flowed voluminous amounts of fuel and air from a pair of four-barrel carburetors, through long, fat, arching intake runners that towered proudly way above the engine.
The setup looked insanely cool. All that visual performance was further enhanced by the fact that a tunnel-ram rarely fits under the hood, except on a few vehicles with massively deep engine compartments (1953-56 Ford F-100s come to mind.) Bolt a tunnel ram on your engine, and it’s gonna show. Period.
It was in the oh-so-tasteful decade of the 1970s that tunnel rams made the leap from track to street, as the burgeoning Pro Street movement sought to apply any and all serious drag-racing equipment to burger-stand cruisers, in a continuing game of one-upmanship. Tunnel rams continued to grow in popularity into the 1980s, as street-machine fashion increasingly welcomed anything that stuck miles-high above the hood — carbs, intakes, scoops, injector stacks, turbochargers, blowers, gauges and whatever else.
As the Pro-Street movement “matured” (kind of like saying Hair Metal bands “matured” isn’t it?) tunnel rams started losing popularity for street use, with builders increasingly favoring GMC-style blowers. For one thing, blowers literally shouted “horsepower” even louder yet; the whine alone from a GMC 6-71 setup was enough to entice street-machine guys into kicking their tunnel ram to side of the garage.
And beyond a blower’s greater visual and audio horsepower, there was an even bigger factor in this choice: Tunnel rams tended to run pretty crappily on the street. Sure, they cost about half as much as a blower setup. But blowers not only looked cool, they made bear-like power all across the rpm range. A GMC 6-71 or 8-71 made a car feel brutally fast at normal street-driving speeds — exactly the opposite of what tunnel rams tended to do.
Alas, as the 1980s came to a close, car builders realized it was kind of nice to actually see what’s in front of them while driving, without looking around all the quasi race-car gadgetry. The last nail in the coffin for the fad was when people figured out they could go even faster with stuff that didn’t hang out in the breeze.
So okay. The tunnel ram has a shaky history on the street. Cool looking. Decent power potential. But tough to get it right for normal driving. So is this an old-school trend that needs to come back?
Maybe. It’s not for everybody. It never really was. But for the right kind of street machine, it’s a killer statement unlike any other.
Perhaps surprisingly, all the pieces are still available brand-new from mainstream suppliers like Jegs, Speedway, and Summit. Heck, for all of you Next-Day-Prime addicts, there are even a few tunnel ram manifolds available new on Amazon.
The key to making tunnel rams work on the street is to be sensible about your carb choices. At the peak of the Pro Street era, it wasn’t unusual to see guys crowning their street-driven tunnel rams with a pair of Holley Dominators. But with an airflow rating of 1050 or 1250 cfm, most street-driven engines can’t handle one of these monster carbs, much less two.
A more sensible choice is a pair of 450-cfm Holley four barrels. It’s still a combined flow of 900 cfm, on an intake with crazy amounts of plenum and runner volume — challenging for street use. But with the 450-cfm setup, you at least have a shot at making it work.
That said, some builders are of the opinion that the 450’s mechanical secondaries are a liability that offsets their smaller overall flow rating. Others say to look for a pair of even-smaller 390-cfm Holleys. Others prefer 660-cfm Holleys … or 500-cfm Holleys … or … hey there’s probably someone out there who says Quadrajets are the ultimate tunnel-ram carb.
Ahhhh, the internet. You know how it goes.
But if you can wade through all the information/misinformation and sort it out, a tunnel-ram setup pretty much guarantees big-time old-school cool factor.
So, waddya’ waiting for? Fifteen hundred bucks or so gets you all the pieces you need, brand-new, ready to go.