The banning of tank carburetors for drag racing was mentioned in another thread. Not wishing to hijack the thread but still thought some might enjoy this picture. This is a picture of a prototype Stromberg 2-barrel that flows 850 CFM on a 4-barrel scale or 1200 CFM on a two-barrel scale. It is pictured next to a Stromberg Model EE-1 (97) for size comparison. Jon
I imagine you wouldn't even get near WOT before the engine would bog down or outright stall, the amount of air flow needed to pull fuel into the passing air stream probably was not attainable by most car engines post war, I want to say that it would lean out more and more as the throttle opened and the air speeds dropped. That's just a guess based off of my dangerous little bit of knowledge I have about carb engineering though.
OK, you’ve got my attention. Now will you please explain 2 barrel scale and 4 barrel scale? I don’t understand how a carburetor could have two different flow ratings. Isn’t CFM a “universal” measurement of flow?
Its really not that hard to conceive. 4V carbs are rated at 1.5 inches of mercury suction. 2V carbs are rated at 3.0 inches of mercury suction. Imagine the engine running at, say, 5000 RPM WOT. An engine with a 4V carb will produce about 1.5 in hg in the manifold. An engine with a 2V carb would have more "suck" going on inside of the manifold, since there is a smaller opening to be drawing fuel and air through. [Imagine drinking a milkshake through a tiny straw vs drinking that milkshake through a short piece of garden hose. Get it?] So 4Vs are rated at 1.5 inches of mercury and two barrels are rated at 3.0 in hg, beacuse that approximates what is going on inside of an engine. Intrestingly, an engine with fuel injection draws less than 1.0 in hg because FI does not have any restrictive venturii. You can convert a 2V carb rating to an equivalent 4V rating by dividing by 1.414. So a 2V carb rated at 500 CFM will draw the same amount of air as a 4V rated at 354 cfm. 500/1.414 A 4V carb rated at 600 CFM will draw the same amount as a 2V rated at 848 CFM (more realistically, four 2Vs rated at 212 CFMs each). 600x 1.414 EDIT: Carbking beat me to it while I was typing LOL. Dammit
… and then there is wet versus dry scales (with thanks to Carbking for educating me many years ago). Love that monster Stromberg. Cheers, Harv
Imagine getting tecked during a battle. That probably sux. wonder what the penalty is for a illegal carb
Hey, Jon; What was the intended use of that big carb - which tank or set of engines, & ~ yr? Reason I ask is, some WWII tanks, & probably Korean conflict, & maybe later too, used multiple engines to get enough power. & I suppose some reliability from the multiple-powerplants theory. IIRC, Chrysler used a bank of ~ 5 or 6 flathead sixes in a circle arranged like a radial engine cylinders. I think gm used 4 or 5 Cadillac v8 flatheads arranged similarly. The Q: since it would seem to me that tuning them individually would be a really bad nightmare, & that if all the engines fed off of 1 or 2 large carbs would work well. Is this what that carb was designed for? I can see the reason for only a 2bbl, & not 4 or more for that. I never got that far into the tank history much when I was a kid. (Modeling & such). Marcus...
So YOU were that creepy guy checking out everyone's junk, huh? The "envy" tells us a little about you, too!
The large prototype would have been for military use. To my knowledge, the only one built, or the only one surviving. The "smaller" 600/850 CFM have a number of military applications, using fairly large Continental engines. More later. Jon
Got called away from posting for breakfast The pictured Stromberg is of the NA design. Stromberg also had another series (H) available as an HD (downdraft) and HH (horizontal, or sidedraft). The H series were S.A.E. size 5 (2 and 3/16 inch throttle bore). Ford used both the HD and the HH on military engines, 2 carbs per engine. Holley also had an S.A.E. size 5, I believe first produced in 1929. It was used on a number of large marine engine, with applications of single, dual, and triple carbs (I guess this was possibly the first tripower? ) The Holley was a type DD. I do not have a comparative picture of the Holley. Difficult to visualize size without a comparison. Oh, and the triple carb version was used by Winton on a 500 HP engine (don't know the displacement). EDIT: just noticed the question on time frame. The Stromberg H series was introduced in 1944; the NA series ran from 1942 through maybe 1952. Jon.
Here is a copy of the "sales pitch" from Holley: Note the venturi air velocity question raised by Nick above is addressed. The Holley Downdraft Marine Carburetor Model D.D.5 – 2-Inch Duplex GENERAL DESCRIPTION A new type of carburetor radically different from existing models has been developed by the Holley Carburetor Company. This new carburetor is of the downdraft type, located above the manifold with the fuel level above the nozzles, so that the fuel flows from the nozzle by gravity. This overcomes the trouble in conventional type carburetors caused by the low velocity being unable to lift the fuel at low engine speeds. Since the Holley Downdraft Marine Carburetor does not depend on velocity to lift the fuel from the nozzle, it permits the use of larger carburetors and freer manifolds without scarificing operation. This change has shown an average increase in horsepower of more than 10 per cent over other types of carburetors. This system is made possible by the use of a shut-off valve to stop the flow of gasoline when the engine is not running. This valve is located between the float chamber and the nozzle, and works in conncection with a diaphragm which is operated by the engine oil pressure. When the engine is running, the oil pressure against the diaphragm causes the valve to remain open, allowing a free passage of gasoline. When the engine stops, this valve automatically closes, and maintains the normal level in the fuel chamber for the next start. This shut-off is also a safety device, because it positively shuts off the gasoline supply as soon as the engine is out of oil, thereby eliminating the possibility of burning out bearings, or more serious injury to the engine. For starting, a by-pass is provided which operates from the choke. This allows the gasoline to pass around the shut-off valve until the oil pressure builds up to operate the valve. Several types of inverted carburetors located on top of the manifold are manufactured, which should not be confused with Holley Downdraft Marine Carburetors. Like the updraft carburetor, these inverted types have the fuel level below the nozzle and depend on the velocity of the air to lift the fuel over the nozzle. To create this velocity it is necessary to restrict the air flow at the venturi. This restriction also limits the volume entering the cylinders at high speed and prevents the engine from delivering maximum power. Holley Downdraft Marine Carburetors, with gravity fed nozzles are not subjected to this restriction. Holley Downdraft Marine Carburetors are used on pleasure, commercial, and racing crafts, and are proving their superiority in all waters and under all weather conditions.
I’d say about the same size (without going to the link) if you look at the pic posted 3 “normal” 2bbl carbs would be about the same as the large one, which would pretty much match up to the eBay carburetor. Also, the eBay carburetor is a stromberg as well.
Ford tank engine GAA, GAN and GAF used 2 strombergs on there 1100 cubic inch engines. I had one years ago, still have one of those big carbs. I believe it's the same as moparboy440's picture.
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