V12 Custom Intake Manifold

I have a 5:3 engine in a hotrod with intake manifolds mounted between the heads. Two 4-barrel carbs are used with these manifolds. I have seen a bridge manifold connecting the two intakes and utilizing one 4-barrel carb. Does anyone know who might be manufacturing or selling this bridge manifold?

How about a picture?

If your manifolds are a cast pair like these, as made by a boat builder in the U.S. then the same fella also made the bridging plenum… to run a single carb… I didn’t bother to buy it as saw little purpose in just running one… though if I ever get around to using them, would likely add a balance pipe between the two m’folds… Any decent fabrication shop should be able to tig up a plenum with appropriate mating surfaces

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Thank you for your response. I think your suggestion of having a bridge manifold manufactured is a practical one. Attached is a picture of my 5:3L V12 engine in a '32 Chrysler roadster.

I am currently using two 390 CFM Holley carburetors. Without over carbureting this engine, there is no other carburetor in the 350 to 390 CFM range that I am aware of. The problem with these carburetors (and all Holley carburetors) if the car is not utilized for a period of time, the gasoline evaporates from the fuel bowls. This allows the float to bottom in the bowls and, upon attempting to restart, many times the needle valves bind in the needle valve tube and causes the carburetor to flood. This problem is mentioned in Holley’s instruction manuals. By usng a bridge manifold with a single four-barrel carburetor, many carburetors are available in the CFM range that would be appropriate for this engine.


Unless being used for really large HP numbers a 600 cfm single carb would be plenty for a Jag V12.

Don’t know about others, but a few more overall Pix of this would be greatly appreciated!

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Indeed Paul… 600cfm is plenty but for the purpose, in a Rod, Carol’s version looks good… but then you can go crazy… this is a local Hot Rod V12… pics taken back in 2017… 4 turbos… regretfully I didn’t hang around to hear it running… and haven’t seen it since

Wow! That is…purple!

Here’s a supercharged V12 in a Healy 3000