Weber's and Inline 6

I think a set of six motorcycle carbs from a 1000cc or larger bike would work well. I've seen them on a Ford 240 six. Those carbs aren't near as touchy as the Webers, probably not as efficient at lower speeds either though.

For those who don't think they would be large enough, remember that the two stage Webers most Jeepers use have a 32 mm primary, 36 mm secondary. My 1000cc Suzuki has a 35-40 mm carb for each cylinder.  You have to remember that the red-line on the bike tach is 9,000 rpm, and it's seen 12,000 before (though rarely!). Even with a small 250 cc (15.26 ci) displacement that's a good bit of fuel! According to the calculator at http://golenengineservice.com/calc/calccarb.htm, a 250 cc engine turning 12,000 rpm needs 52.90 cfm (one cylinder of the 1000), 9,000 needs 39.73 cfm. One cylinder of a 258 (43 ci) turning 4,200 rpm needs 52.26 cfm, 3,000 rpm needs 37.33 cfm. So high end power would be limited by the carbs, but throttle response and low end power should be wicked, as John (nosigma) will attest! My car rarely sees more than 3,000 rpm, as is the case with most street driven sixes. Most driving is done in the 2000-2500 rpm range.

I don't think the throttle and fuel would be too hard to rig. On mine the carbs are all held together by a small piece of angle screwed to the back of the carbs. Fuel delivery is via a tube with o-rings that pushes into a socket between the carbs, so it flows from one carb to the one next to it. The end carbs have the outside hole plugged. One of the tubes has a T for the fuel line to connect to. The throttle shafts are all connected in a similar fashion. Should be easy enough to make longer tubes and throttle shaft connectors. I think I'd eliminate one of the center carbs from two sets of four (two sets of three), then use a Y in the fuel line to feed each. It shouldn't be hard to use two throttle cables from the carbs connected to one to the gas pedal. Some bikes are set up that way -- usually two cylinder (two carb) engines.

Here is a picture of the installation.  Note how tight the air horns are on the center carb to the fenderwell.  I had to use a set of special short 270 degree lip air horns at this location and build a custom airbox to fit.  On the rear carb the airhorns and the foam socks tuck in above the steering shaft and under the master cylinder.  I had to shim up the DS engine mount about 1/2 inch and adjust the transmission mount so they would fit and not hit when the engine rocked under torque load.  Its a tight fit with about 1/2 inch up travel before they hit the master and 1/4 inch down travel before they hit the steering shaft.  This was just one of many delicate adjustments needed to get everything to work right.  The LONG runners are the key to building the torque.  I also used an old set of LONG primary 258 Clifford split headers that were modified to fit the 4.0 head.  Clifford Engineering made great stuff, Clifford research not so great.

SixPack did the same thing but with an IR injector set up.  Much smarter way to go.

John

It wouldn't be hard to bend some tubing and make a pair of three cylinder intakes. One tube bent in a "U" connecting cylinders #1 and #3, then cut a hole in the center and weld #2 in. Same for the rear three. Well, you have to mount the carb, so a plenum box would be at the junction point, but you get the idea. Running a pair of 2Vs or even 1Vs with such a setup would be better than the single long intake. Mount the NOS fogger jets in the plenums.

If you want long runners, use tubing and curve them over the valve cover then mount the Webers.  Something like that would work in a Jeep, probably not enough room in something like the American, but keep the tubes right on the valve cover then dip doen on the passenger side and I think it would work. Getting to the distributor would be another matter! With a 4.0L use the DIS system.

Not just a matter of grabbing some tubes and bending them..... you need to calculate the inside cross-sectional area and tube length (meaning TOTAL length including any plenum and the head runner distance to the valve)
Otherwise, you are just bending tubes and hoping for an intake that works ok.
Takes some figuring to get it right - to coincide with the cam and RPM range you want, and where you want the torque shifted to.
The 94 4.0 intake, for example, has 9.5" long runners and a cross sectional area of 2.234 sq. in
The distance from the intake valve to the port opening is 3.5" so the total tube length is 13" plenum to valve.
According to the factory calculations, the intake runner area and length are tuned to resonate and produce an inertial supercharging effect at 5000rpm. About right for the peak HP RPM of a 4.0 high-output engine.

It's a good looking setup, reminds me of an engine I would love to own, the Chrysler 265 that the Aussies got to have in their Valiants.
http://en.wikipedia.org/wiki/Chrysler_Hemi-6_Engine