Old School Hot Rod 3x2 bbl intake

[Trevor]

I just picked up a 40-year-old 3x2 Edelbrock manifold with 3 Rochester carbs for my SBC. Never tuned one before anyone else played with a multi - carb - downdraft on a non-computerized American V8? Um, Gee Officer, What EGR?

 

Among the rumors I have heard:

They're hard to tune, one cyl runs rich, the rest run lean, etc....

Throttle linkage is not linear, the outer 2 butterflies open later so she won't flood at lower RPM and a faster rate so all 3 reach WOT at the same time.

 

For looks only- You can block off the 2 outer carbs and get decent gas mileage driving around on the center carb only, until "race day" then uncork the 2 outside carbs.

[Guest Phil1934]

True triple 2 bbl end carbs are hard to come by. They had thicker throttle blades to seal off better and no idle screws. If you have these, you are golden. If not, the bases are available in repro to convert yours.

[SpeedRacer]

Got one of those on my car (but with a single plane Offy manifold so it would fit under the hood). http://www.hybridz.org/Review/0002/Ferrari_GTO.htm

 

You can get parts from Vintage Speed http://www.vintagespeed.com/ or Larry at Automotion http://www.hotrodcarbs.com/home.html

 

As Phil1934 mentioned, the base plates of the end carbs are very important. The best ones are custom made because the throttle blades MUST seal completely!! Only the middle carb has idle screws so adjusting them is easy. The end carbs only have an accelerator pump and main jets in them. No choke, power valve, idle curcuit, etc. Sounds like you have the right linkage but you can get different linkage setups from Vintage Speed or Automotion if you need it.

 

PS At WOT the carbs sound almost as good as the exhaust!

[Tim240z]

I guess you could always find some old junky carbs and hide some injectors in them and have the best of both worlds.

Tim

[blueovalz]

I believe the factory(s) set these up with the middle carb being the only one for idle adjustment, and the two outside carbs are staged.

[Trevor]

I guess you could always find some old junky carbs and hide some injectors in them and have the best of both worlds.

 

My thinking also. That's one reason I found a "relatively late" manifold with 4-bolt Rochester carbs, rather than the 3-bolt Stromberg carbs. Figured I could employ three old VW/Porsche -type 2-barrel Webers for an exotic look.

 

The carbs look like a matched set. Only the center has the idle cicuit and choke. The end two never had chokes - obviously a different casting.

 

Thanks!