Dual Carb Idea.. Your input please

[Anonymous]

Just kicking around the idea of dual Pinto (4-cyl) staged 2 bbl carbs on my 200. I think they're Autolite 5200 carbs.
Has anyone ever tried this?
If so, how'd they run?
Would the engine need to be cammed to take advantage of 'em or would they work on a basically Stock engine w/ a (non-header) low-restriction exhaust?
If you use two from a '72 2300 CC (122 C.I.) 4 cyl, then would two of 'em be good on a 200 or 250?
They'd probably have to be tuned and modified, but the two small primaries might equal out to roughly the same CFM as a Stock 200 1 bbl (about 185-195 CFM, depending on the carb).
If so, then there'd be no "over-carbureted stumble" on Tip-In,
and the staged secondaries could up the CFM nicely when they kick in.
Guess it would depend on the actual CFM of the Autolite 5200 carb.
Anyone have that info?
Thanks!

 

[xctasy]

Some BMW'S and Mercedes-Benz 2800 cc sixes had such set ups in Germany. They used Solex versions of the 5200 style carb. The idea is to use small primary venturis normaly, and then switch to all chokes when at wide open throttle (WOT). Not any different to a four barrel Q Jet, Autolite or Carter Thermoquad. All you're doing is spliting a four bareel carb really.

Most four barrels suffer from poor mixture distribution on six cylinder cars. On V8's a four barrel can work perfectly. In Australia, 4bbl carbs are used on many aftermarket six in line manifolds for Fords, Holdens and Chrysler even had a stock AFB Carter on the 245 cube Hemi six. But they all were less sucessful than single big two barrels because of the mixture distribution causes flat spots. So the idea of twin deuces is not a bad one at all.

Splitting the carbs is only a good idea if it can be done with a proper linkage. BMW and Daimler Benz gave up on dual carbs because injection systems were more economical. Opel used big four barrel Solex carbs, and these were thirtsy.Since the Holley/Weber is a good carb for up to 125 hp unmodified on a four cylinder Pinto, it should be able to suit a mild 200 without over jucing it. In Europe and New Zealand, lots of little 1.6 liter Pinto engines were used in Cortinas and Capris with the same jetting as the 2 liters, but with different idle settings. These cars had about 75 horsepower. In theory, two of them could sit on a six and give 150 hp.

The secondary ciruits are all machanical, so if they are phased in to reach WOT at the same time, then it should work. Sixes produce much better vaccum, so they would run very lean off idle and too rich at WOT. Dyno time, and a selection of emulsion tubes, idle correction jets and other jets would have to be used. I'd suggest you copy a Merc or BMW 3000S style linkage to make it all work out.

I think you could make it work, if your able to handle the jetting.