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


Jagster here: talk about coincidence! I was thinking about this very thing at breakfast this morning, and wondered if anyone had produced such a manifold. I have a 92 XJS and would like to simplify the mess we call ‘linkage and such’ that clutters the top of the engine. A single, 4 barrel affair should work just fine, and your basic Edelbrock 600 cfm carb would be all you would need for the street.

Gee, I would think it’d be a lot easier to just fix that issue than to completely rework the intake system for one large carb instead of two small ones. Just epoxy a little step to the bottom of the float bowl so the float cannot fall far enough to jam the needle.

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I concur, TAOTB is right. You seem to want to create a more expensive problem that you are solving. My Alfa has a pair of 40 DCOE Webers and, after sitting for a week or more, I have a similar issue of the fuel draining out. It doesn’t cause the same flooding problem, I just need to churn the engine for a little longer to get it to fire. Or I could install that electric pump, that I bought years ago, to pre-prime the carbs. Either way. I’m not considering a drastic change for a small amount of convenience.

A 600 would be MUCH more than plenty!

If I were going to build a V12 hot rod, I’d like it to look something like this.

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where are the water manifolds on that engine??

With two four-barrels

With a bridge manifold and single four-barrel

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The latter will give you better low-end drivability, and better throttle response.

Do you by chance have the name of the manufacturer of the manifolds? You mentioned it was an American company. I would like to find them and place an order for one.

The manufacturer of the base manifold and the bridge manifold is Kelly Berg, 2009 Northshore Dr., Bellingham, WA 98226. His phone number is (360)319-9528.

I think you should know that Mr. Berg informed me that under certain weather conditions the bridge manifold has the potential to form ice. The modification I made, which I found that at this point I have not needed, is as follows: Two 12 volt heat strips that are designed for continuous operation, which I attached to the bottom of the center section (directly under the carburetor). I am using a 600 CFM Summit carburetor which performs very well.

Many thanks, and if the beast hiccups, I will have a plan B to rectify the problem.