Duel Carbs

[Joe K]

Originally Posted by MikeK

Well, that manifold looks kinda cool, but from a flow bench point of view the traffic jam at that intersection can't possibly be good. Reminds me of those 'put a 4bbl on your 2bbl manifold' adapters Warshawsky used to sell.

More sense?



This may point up (see the name) for downflow carbs. I think Simmons made something similar for their Wizard Carbs, but pointing down.

Joe K

[California Travieso]

Joe,

Secrets of Speed (www.secretsofspeed.com) has the VORTEX which is a Dual Up or Down Draft Intake Manifold. Great unless you like welding.



​David Serrano

[Joe K]

Thank you. I see the VORTEX retains the "hot spot" which the carb I showed seems to omit. I can't help but think the hot spot would improve economy without sacrifice to speed.

Joe K

[denniskliesen]

Originally Posted by Joe K

Their big sell point of Eutectic/Castolin is the weld can be machined. Nickel based cast iron repair cannot be machined, but it can be ground with difficultly. Not a place to use your carbide burrs.

Joe K

That's good to know about machining. I usually only had to clean up with a grinder from memory.

[denniskliesen]

Originally Posted by hardtimes

Hey dennis,
x2 on your carb conclusions !

Regarding the cast iron welding. From speaking with well known/recommended companies and from reading, I've been informed that if you 'repair' anything cast iron, with anything other than cast iron...they will not be able to repair that part...without having to cut out all of the non cast iron and then use cast iron repairs(expensive done right). Then maybe not repairable and then very expensive. They will not take on any work where previous repairs are done this way, i.e.- nirod,etc) So, if a guy has RARE/expensive item...say antique head / block with nirod etc., that needs more fixing...good luck ?

You have a good point there. Years ago I remember getting reconditioned engine blocks, mostly Cummins from a place in LA called Northwest Motor Welding. If you've had experience with the old cummins engines they left a wear pattern on the top of the block from the head gaskets. Sometimes a block could be cleaned up, but other times the block had to be scrapped. NWMW, would braze the top of the block and then machine it to a flat surface. It looked unusual and did not last. Leaking head gaskets on those engines were very common.

[Synchro909]

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Originally Posted by California Travieso

Joe,

Secrets of Speed (www.secretsofspeed.com) has the VORTEX which is a Dual Up or Down Draft Intake Manifold. Great unless you like welding.



​David Serrano

Talking from a RHD perspective, that looks to be a MUCH better configuration and a manifold like that would not be difficult to fabricate. Neither would a progressive linkage so most of the time, you are only using one carb. Air cleaner would be another matter though. Think I'll stick with my downdraught early Holden Strombergs. BTW, they have exactly the same flange as the Zeniths etc.

[Sparky]

Originally Posted by California Travieso

Joe,

Secrets of Speed (www.secretsofspeed.com) has the VORTEX which is a Dual Up or Down Draft Intake Manifold. Great unless you like welding.

​David Serrano

Yup, here's mine with dual B carbs. Runs great, no jet changes were required. They work in tandem, not progressively.

[Synchro909]

Originally Posted by Sparky

Yup, here's mine with dual B carbs. Runs great, no jet changes were required. They work in tandem, not progressively.

Nice, and the rear one gets warm air!

[Chris Haynes]

Are dual carbs involved in a duel? :-)

[mshmodela]

One might guess had two cards your mpg would be even less...

[Joe K]

Originally Posted by Chris Haynes

Are dual carbs involved in a duel? :-)

Dueling Banjos (classic movie scene and a Burt Reynolds theatrical high point as he had no acting to do) did come to mind.

https://www.youtube.com/watch?v=1tqxzWdKKu8

Joe K

[Railcarmover]

downdraft better than updraft..use a snail ^^ to synchronize them..the key is balancing the two.Zeniths and Strombergs are sexy but webers are the way to go for drivability IMO,a pair of ICT's on short manifolds with a vacuum equalizer tube..

[mike657894]

the carbs get away with similar mpgs and jets due to your still pulling 3.3 liter of air every two rotations. at the same mix of air to fuel. On pinch point the smallest pinch point is the carb venturi. and i dont have the mesurments. but a little math. a one inch hole has the area of 3.14 and a two inch hole has the area of 12.57 therefor a pipe that is twice the size will flow 4 to 1 against a smaller hole.

[KMeredith87]

I have a manifold like that one sitting in my garage...haven't used it yet but would like to. What have you guys found to be the best card to run two of? I have multiple Zenth A, B and tiliston carbs laying around.

[Sparky]

The maker of my manifold recommended B carbs or Tillotsons. It may have something to do with the way the float works on the A carbs.

[Synchro909]

Originally Posted by mike657894

the carbs get away with similar mpgs and jets due to your still pulling 3.3 liter of air every two rotations. at the same mix of air to fuel. On pinch point the smallest pinch point is the carb venturi. and i dont have the mesurments. but a little math. a one inch hole has the area of 3.14 and a two inch hole has the area of 12.57 therefor a pipe that is twice the size will flow 4 to 1 against a smaller hole.

A hole of 1" diameter has an area of .794 sqin. A hole of 2" dia has an area of 3.14 sqin but as you say, one is 4 times the other.