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!
 
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 ?
 
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
 
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.
 
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.
 
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.
 
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.
speedsterengin.jpg
 
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
davidpgh1@aol.com
 
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....
 
Resurrecting this thread. I recently installed a Vortex intake on my A with two Marvel carbs.

It needs some more tuning, but hoping to get some insight from those who have done this modification.

For those with Marvel's, do you run the GAV, Idle Adjustment, and Throttle Adjustment closed on the rear carb?

On the forward carb, how far out do you run the idle adjustment screw? I've found I have a bit of a gallop with the screw turned out 3/4 of a turn. It runs smoother as I turn it out beyond 3/4 but does not seem to reach a point where it sounds any different indicating the mixture is too rich.

When I was running a single carb, this adjustment seemed much more sensitive.

I need a bit more work on my linkage before I can test again. The rear throttle shaft arm is bent, so it only opens 3/4's when the front carb is at full throttle. I have a spare shaft I'll try to swap in or bend this one back closer to the front carb.
 
On one of my cars, I used to run a downdraught single barrel Stromberg. The barrel is the same size as the first barrel on a Webber. I find I virtually never use the second barrel on my Webber so I am quite satisfied with the Stromberg. To maintain some resemblance to original, I have now fitted a Model B carburettor (It had the usual broken ear but I repaired that). Performance is about the same but it use more fuel and with no accelerator pump, I have to take double de clutching a bit slower.
An air cleaner on he Stromberg was MUCH easier to arrange that for the B Carb.
 
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