round bore billet updraft carbs

[CFS Carbs]

I have re-designed some of the round bore updraft carbs that I built some years ago. The reason was to make them shorter and more compact, to make it easier to fit them in cramped quarters, without giving away any of the air flow capacity or the ability to meter fuel efficiently. These are 4 1/8" tall, which is about 2 1/4" shorter than the old designs. The larger one is 385 cfm, and the smaller is 250 cfm. This design can be used to build carbs that range from slightly below 200cfm to slightly over 400 cfm. Each carb is custom built to suit the tractor its going on.

 

[CFS Carbs]

As you can see,these carbs use a Holley fuel bowl, a custom accelerator pump housing, and a direct link from the throttle shaft to operate the accel pump. The metering plate (not shown) is jettable on both of the metering circuits, on jets and air bleeds. The whole carb design is concentrated on helping the engine make better power over a wide rpm range, AND have the drivability needed to control tractor speed and engine power.
The design on the throttle body allows the use of an adapter plate (usually 3/8" thick), to allow the carb to be turned 90 degrees, or to adapt to a different center to center distance of the intake manifold flange bolt holes, and/or to adapt to manifold flange bore that is slightly larger or smaller than the throttle bore of the carb. The adapter plate can handle any one of those situations, any 2, or all 3. It is recommended that the intake manifold bore, at its flange, be the same size as the throttle bore of the carb. But sometimes that isn't possible or practical.
Norm Schenck Comp Fuel Systems Birch Run, MI

This post was edited by CFS Carbs on 10/22/2023 at 09:34 am.

 

[Loosehandle]

Classifieds?

 

[CFS Carbs]

Not sure what you're asking.

 

[CFS Carbs]

Would anyone be interested in a side draft version of this carb design? The Holley fuel bowl wouldn t lend itself well to that configuration, but I think I have found another type of bowl that would. It would be just a matter of building one, and working out the accelerator pump aspect. Comments?

 

[Neutron]

Just found this and had to make an account to reply!
I'd definitely be interested in a sidedraft version of these! I think anyone with a old engine requiring the larger sized updraft would love a option for newly made replacement. For example, I have a Cletrac BGS that has a big 6cyl Hercules JXC. That engine uses a Zenith 63 updraft. That's the big zenith and new reproduction zeniths are not sized that large. The other issue I run into regularly is the vacuum controlled power valve inside mine will get stuck/frozen occasionally and it leads to incredible frustration and a teardown of the carb. If there was a new and better option to replace that carb, I would buy one!