Dual updraft carburetors

[gilitos]

There's a couple of recent threads related to Webers, Strombergs, dual Strombergs, etc., but to me the look of dual updrafts has always been the stuff. They look like a bargain when you consider the price of the manifold and one or two Tillotsons. I've also heard that they're too much for a stock motor. Who has experience with dual updrafts? Whaddaya think?--Giles in Cincinnati

[Dave in MN]

Giles,
I am building an era "hop up" and have a dual updraft manifold with two "B" Zenith carbs set up by Dave Renner @ Renner's Corner. Prior to jetting them, he asked a lot of questions as to my valves, cam, displacement and my expectations of operation. Dave's comment was that the dual set-up was a bit to much carb for my engine with stock jetting. I do have 1.7" intake valves, enlarged intake passages and a .340 lift cam from Bill Stipe.

I have yet to put it on the road but it ran pretty well on the engine stand during break-in. I'll know more this spring.

Good Day!
Dave in MN

[Vanspeed]

I would love to see your setup Dave, how are you running the gas lines? Also the choke rod can't be used right?

[Dave in MN]

Until I get the engine in the car I am not sure how I will plumb it permanent...I just used rubber gasline for the break-in period. I'll put your name in my log and email you something when I get it installed. If I fall behind, I will put the engine in my driver for the summer so I can get it through the full break-in.
Choke rod: Only one carb is used to choke and adjust the mixture to start. The other GAV is set up with a short adjustment fitting that allows you to adjust the mixture...with the hood open.
Dave in MN

[Slantwindshield]

I am running dual Zenith updraft carbs on my Slantwindshield. Tour without any problems, high comp head, lightned f/w, and a Mitchell. Post you e-mail and I will forward pictures. Howard

[Milton]

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My first modification to my 30 sedan back in the fifties was a pair of zeniths and they were great. Just a bit over carbureted but a throttle stop took care of that.

[Charlie Stephens]

Originally Posted by Vanspeed

I would love to see your setup Dave, how are you running the gas lines? Also the choke rod can't be used right?

A friend of mine ran 2 updrafts with a Trojan manifold. The guy that set it up (Wes Cooper) said a choke on one carburetor was enough and he was right.

Charlie Stephens

[lindy williams]

I'm running two model A zenith carbs side by side. With this set up you can idle one one carb and use the choke rod. It is easy on this installation to design a progressive linkage so that you run on one carb until about 1/2 throttle.

[Milton]

Originally Posted by lindy williams

I'm running two model A zenith carbs side by side.

This sounds neat, got any pics you can post?

[Ronnie Lawson]

I plan on adding this to my 1929 Town Sedan.
Ron
IMG_0103.jpg

[wardkew]

Ron, who makes that intake??

[Ronnie Lawson]

I don't know who made the intake. I bought it at Hershey about 10 years ago.

[Ray in La Mesa]

The side by side updraft intake is a stock A intake with a 90 degree ebow braised on with a flange for the outer carb. The article on how to make one is in Vol.! #4 issue (April '92) of SECRETS OF SPEED by Charlie Yapp. I made the one on my pickup about 15 years ago and it is fantastic.

[Dave in MN]

Originally Posted by Ronnie Lawson

I plan on adding this to my 1929 Town Sedan.
Ron
Attachment 34944

Thanks Ron for posting this picture...this setup is exactly what I need to make my system work and the progressive idea from Lindy to kick in the second carb above 1/2 throttle...awesome.
Looks like I'll be putting my other intake from Charlie Yapp on the shelf.
Thanks All!
Dave in MN

[hardtimes]

Originally Posted by Ronnie Lawson

I plan on adding this to my 1929 Town Sedan.
Ron
Attachment 34944

Ron,
Who makes that 'two in one' gas line setup. Do you send them measurements/drawing of what you want/need what?

[shock]

Heres Mine

[Jason in TX]

THAT is prettty smoooooth!

[Sparky]

Shock, are those dual Zeniths? Any stalling problems?

[Vanspeed]

Hey Ron, what carbs are those? I am really liking the carb setups here, Shock, that is a great looking motor.

[shock]

Originally Posted by Sparky

Shock, are those dual Zeniths? Any stalling problems?

Yes they are regular model A Zeniths......no stalling at all.

Note the plates that I made to index the rear of the carbs out aprox 22 degrees so the floats no longer pivot in the direction of the vehicles travel.

[Jim MN]

Great looking setup, and the offset plates are a great idea -- where are the intake scoops from?

[pick]

Shock I like your carb stacks. Keep big debris out without restricting the flow. Real nice. I've been contemplating fabricating something similar for my dual strombergs. Were yours a purchased item or self made? they look great!

[Mikeinnj]

Has anyone dyno'd these set-up's to see if they really increase performance or are they just burning extra gas and washing down the cylinders ?

[Vic in E-TN]

Shock:
I noticed the filter inside your glass fuel bowl. I have tried this several times and have always had a fuel problem with these. At about half a tank they do not flow and the engine will not perform. Have you actually run the filter?

Does anyone have any other comments on the filter?

I had a debris problem on my 29 CCPU last Saturday and had to abandon the truck and drive my Ranger to the Car Games my club was running. Yesterday I drained the tank and found that my standpipe above the shutoff had rotted off. Cleaned the tank with water wash today. I left it out in the sun today, 94F, and will run some alcohol to pick up the traces of water tomorrow.

Vic

[Sparky]

Originally Posted by Mikeinnj

Has anyone dyno'd these set-up's to see if they really increase performance or are they just burning extra gas and washing down the cylinders ?

Lots of dyno results here:

http://www.modelaparts.net/dyno.htm/dyno.html

[CA Victoria]

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Interesting design, does anyone have a copy of SECRETS OF SPEED that you would like to sell?

Vol.1 issue 4 (April '92), original article byCharlie Yap.

[Purdy Swoft]

I've been running dual updraft model B carbs on my speedster for 12 years. I run original jets in both carbs and it is NOT too much for a stock engine. I ran this set up on two different model A engines in this car. The first engine had a high compression head of unknown make but had heart shaped combustion chambers and I am guessing to have been around 5 to 5.5 ratio. It was the fastest model A that I had ever owned. It was running pretty warm and spitting a lot of water out the overflow tube so I blamed it on the head. I replaced the head with a stock head. The car still had cooling problems but the problem was found to be a light duty two row radiator that couldn't handle the flow. I replaced the radiator with a good original and continued to run the dual carb set up with the stock engine with no problems with the stock jets in the model B carbs that I had went through myself. There was a noticable difference with the dual carb set up even with the stock engine but not nearly as much as with the hc head and dual carb set up. I built the second engine bored .060 over stock valves, no special port work. On the second engine I used a 5.9 head, a super street Winfield 3/4 race cam, straight 40 inch exhaust and a nos Mallory B hive 30.000 volt coil. This one was a real monster as compaired to the first one. I was still running the cast iron uniflo dual updraft manifold that Steve Becker sold me out of his personal collection. I ran the model B carbs with original jets. When the engine reached sufficient rpm for the high speed curcuit in the B carbs to kick in you really needed to hold on, It will move like a bat out of hell!!!

I run a Trojan cast iron dual updraft on my roadster. The engine is a very low milage engine with standard size pistons and original babbit. I just cleaned up the engine and overhauled it I enlarged the intake ports and the area under the intake valves. I smoothed out the rough cast exhaust ports but didn't really enlarge them so as not to hinder low speed torque. I'm running a Winfield 3/4 race cam and a 5.9 head. I run a completely gutted muffler and a Pertronix flame thrower coil. I also use a model B flywheel that is lighter. This model A has no problem keeping up with traffic on the highway. It gets better gas milage than my other model A's with single original Zenith carbs. My wife drives this car. I set the float level the same as I do all other B carbs and there is no problem with stalling apon brakeing as when coming to a stop. I run the back carb with the gav closed all the time and have the choke connected to the front carb. I open the front gav i/4 to 1/2 turn for cold cranking but run both gav closed at all other times. I really like both of these set ups both in looks and performance. They both give more power and better gas milage.

I also have one of Charlie Yapps new aluminum dual updraft manifolds that I haven't yet used. This manifold has stock runner size at the flanges. I plan to use a pair of nors Tillotson model XF carbs with this one. The tillotsons are lighter in weight and should be better to use with an aluminum manifold. Dyno tests were conducted with this manifold with Tillotson carbs and showed a 10 horsepower increase on a stock engine. It was also tested with B carbs and didn't show any increase over the tillotson carbs. My opinion is that if the manifold runner size was increased to model B size that Charlies manifold would better respond to the B carbs with a few more horsepower. The weight of heavier model B carbs may not be good for an aluminum manifold.

[lindy williams]

Hi Giles, I have two updraft zeniths used with a progressive linkage. Works great. Send me an e-mail at [email protected] and I'll send you a picture.

[Purdy Swoft]

Here is a picture of the dual updraft setup that we run on our roadster. The manifold is a Trojan cast iron unit that was produced back in the day and maybe up until the early fifties. I'm running model B carbs with original jets. I would have posted pics the other day but I'm not real swoft at posting pictures. I had to wait for help. If the picture posts ok I will post more pictures of the Uniflo set up on our homemade speedster.

[Purdy Swoft]

I'm haveing a little trouble with photo bucket. The picture is somewhat small but here is the setup with the Uniflo cast iron manifold and dual B carbs with original jets on our speedster. This one was easier to set up. I was able to use the original opening in the firewall for the choke rod. This manifold doesn't stand out as far from the engine as the Trojan manifold on the roadster above. Note the rear carb is sort of cocked outward at the throat so as not have to breathe right off the rear of the exhaust manifold. The Uniflo manafold was made for the model B and has larger runners, it performs better and when the high speed circuit cuts in on the B carbs you can really feel it. I don't use breathers and beleave it would run too rich that way.

[Davidpgh1]

Greetings. I came across RAY IN COSA MESA's old post dated March 7, 2011 (#13):

"The side by side updraft intake is a stock A intake with a 90 degree elbow braised on with a flange for the outer carb. The article on how to make one is in Vol.! #4 issue (April '92) of SECRETS OF SPEED by Charlie Yapp. I made the one on my pickup about 15 years ago and it is fantastic."

Any idea where I could obtain a copy of volume #4 of Secrets of Speed?

Regards,

David
[email protected]

[Y-Blockhead]

I say nix the dueling carburetors and throw on a hair dryer...

[ronn]

Shock, very clean. love it!

[Chuck Sea/Tac]

Google Charlie yapp secrets of speed

[Gene F]

This highspeed circuit for the B carb....that the little metal tube when you split the two halves?
I have a B-carb, and the IB330 cam, and big valves H/C head, and 30 lbs flywheel. It runs good (fresh engine -just broke in really). It runs good but maybe I don't have the hang of the GAV? I rebuilt the B-carb, and dipped it in berryman chem dip... The float was set with the little plastic tube.

These duals look great, but I'm unlikely to go this route without a buddy that knows what he/she is doing....

[updraught]

Originally Posted by Davidpgh1

Any idea where I could obtain a copy of volume #4 of Secrets of Speed?
Regards,
David
[email protected]

Volume one no's 1-4 were reprinted as a "best of" and "may" be available. Otherwise you can get a PDF version here.
https://www.secretsofspeed.com/soss-index

[31a]

I have a dual updraft manifold and the linkage if interested PM me and we can talk about it