Oval Bore single barrel carb

CFS Carbs · Sep 28, 2023

I've developed an oval venturi/oval throttle bore single barrel updraft carb for large displacement vintage pulling tractors. The oval shape allows for a compact high flowing single barrel carb. This prototype flows 450cfm at 1.5"Hg, and is slightly smaller than the Holley 2300 series two barrels. This carb is designed to work on engines in the 250-300hp range. There is room to scale that flow up or down, to suit specific engine combinations. This carb can also be made in a side draft version, with a slightly different fuel bowl configuration. If you are interested in a carb like this, for any engine in the 150-350hp range, please contact me. I also build billet round bore tractor carbs in the 250-350 cfm range.
Norm Schenck/CFS carbs

This post was edited by CFS Carbs on 09/28/2023 at 12:19 pm.

CFS Carbs · Sep 28, 2023

This post was edited by CFS Carbs on 09/28/2023 at 12:24 pm.

CFS Carbs · Sep 28, 2023

535353m · Oct 6, 2023

how do we adapt that to a round manifold in tight spaces

CFS Carbs · Oct 6, 2023

There are some nice oval to round transition tubes that can be used to act as an adapter and part, if not most of the manifold's plenum. I have one that is for the air inlet end of this carb, and one of a slightly smaller size would do the trick to adapt it to the intake manifold.

This post was edited by CFS Carbs on 10/06/2023 at 11:54 am.

CFS Carbs · Oct 6, 2023

pictures

CFS Carbs · Oct 6, 2023

The adapter tube would not need to be as long as this one, and probably couldn't be, being that vertical space , as well as space around the sides, is limited. That is why I kept the overall height of the carb to a minimum, without giving away its ability to meter fuel and flow air well.
What type and size engine are you working with?
Norm Schenck/ Competition Fuel Systems / Birch Run, MI

CFS Carbs · Oct 7, 2023

I believe that this adapter could also be made to work, with some modifications.

CFS Carbs · Oct 8, 2023

The cast aluminum adapter, even if it is thick enough to be modified to accept the oval bore carb, would definitely cause some significant flow loss. The flow loss could be enough to make it not worth using the big oval bore carb. The performance of your tractor engine would probably be better with a round bore carb that was designed to fit your intake manifold, in the confined space you have. I build those,too.
I'm currently re-designing some of the round bore updraft carbs to be considerably shorter on vertical height, and more compact on the sides, all without giving away any of the good flow and fuel metering characteristics. These round bore carbs are in the 250-350 cfm range. I'll post some pictures of the 250 cfm carb when I get it done. It will be at least 2" shorter than the old design.

Oval Bore single barrel carb

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