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03-04-2011, 02:05 PM | #1 |
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Dual updraft carburetors
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
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03-04-2011, 02:14 PM | #2 |
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Re: Dual updraft carburetors
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 |
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03-04-2011, 03:51 PM | #3 |
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Re: Dual updraft carburetors
I would love to see your setup Dave, how are you running the gas lines? Also the choke rod can't be used right?
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03-04-2011, 03:56 PM | #4 |
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Re: Dual updraft carburetors
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 |
03-04-2011, 04:34 PM | #5 |
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Re: Dual updraft carburetors
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
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03-04-2011, 11:42 PM | #6 |
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Re: Dual updraft carburetors
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03-04-2011, 11:55 PM | #7 | |
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Re: Dual updraft carburetors
Quote:
Charlie Stephens |
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03-05-2011, 08:20 AM | #8 |
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Re: Dual updraft carburetors
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.
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03-06-2011, 12:36 AM | #9 |
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Re: Dual updraft carburetors
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03-06-2011, 04:57 PM | #10 |
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Re: Dual updraft carburetors
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03-06-2011, 07:49 PM | #11 |
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Re: Dual updraft carburetors
Ron, who makes that intake??
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03-07-2011, 09:04 AM | #12 |
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Re: Dual updraft carburetors
I don't know who made the intake. I bought it at Hershey about 10 years ago.
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03-07-2011, 09:53 AM | #13 |
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Re: Dual updraft carburetors
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.
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03-07-2011, 11:59 AM | #14 | |
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Side by side dual updraft carburetors
Quote:
Looks like I'll be putting my other intake from Charlie Yapp on the shelf. Thanks All! Dave in MN |
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03-07-2011, 02:50 PM | #15 | |
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Re: Dual updraft carburetors
Quote:
Who makes that 'two in one' gas line setup. Do you send them measurements/drawing of what you want/need what? |
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03-09-2011, 04:30 PM | #16 |
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Re: Dual updraft carburetors
Heres Mine
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03-09-2011, 04:36 PM | #17 |
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Re: Dual updraft carburetors
THAT is prettty smoooooth!
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03-09-2011, 07:17 PM | #18 |
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Re: Dual updraft carburetors
Shock, are those dual Zeniths? Any stalling problems?
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03-09-2011, 08:21 PM | #19 |
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Re: Dual updraft carburetors
Hey Ron, what carbs are those? I am really liking the carb setups here, Shock, that is a great looking motor.
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03-11-2011, 12:34 PM | #20 |
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Re: Dual updraft carburetors
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. |
06-07-2011, 03:48 PM | #21 |
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Re: Dual updraft carburetors
Great looking setup, and the offset plates are a great idea -- where are the intake scoops from?
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06-07-2011, 06:23 PM | #22 |
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Re: Dual updraft carburetors
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!
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06-07-2011, 07:58 PM | #23 |
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Re: Dual updraft carburetors
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 ?
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06-07-2011, 08:50 PM | #24 |
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Re: Dual updraft carburetors
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 |
06-08-2011, 10:16 AM | #25 | |
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Re: Dual updraft carburetors
Quote:
http://www.modelaparts.net/dyno.htm/dyno.html |
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08-23-2011, 10:01 PM | #26 |
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Re: Dual updraft carburetors
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08-24-2011, 11:33 AM | #27 |
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Re: Dual updraft carburetors
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. |
08-24-2011, 07:01 PM | #28 |
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Re: Dual updraft carburetors
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.
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08-27-2011, 10:12 AM | #29 |
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Re: Dual updraft carburetors
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.
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08-27-2011, 01:37 PM | #30 |
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Re: Dual updraft carburetors
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.
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12-29-2021, 12:22 AM | #31 |
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Re: Dual updraft carburetors
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] |
12-29-2021, 12:08 PM | #32 |
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Re: Dual updraft carburetors
I say nix the dueling carburetors and throw on a hair dryer...
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12-29-2021, 12:34 PM | #33 |
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Re: Dual updraft carburetors
Shock, very clean. love it!
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12-29-2021, 01:48 PM | #34 |
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Re: Dual updraft carburetors
Google Charlie yapp secrets of speed
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12-29-2021, 06:45 PM | #35 |
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Re: Dual updraft carburetors
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.... |
12-29-2021, 07:53 PM | #36 | |
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Re: Dual updraft carburetors
Quote:
https://www.secretsofspeed.com/soss-index |
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01-01-2022, 12:51 AM | #37 |
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Re: Dual updraft carburetors
I have a dual updraft manifold and the linkage if interested PM me and we can talk about it
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