Some comments on another thread prompted it to post this thread: Inline engines, multiple carb set-ups, carburetors We have a lot of customers ask about carburetors for multiple set-ups on inline engines. In our opinion, the leading candidate for aftermarket multiple carbs on an inline engine is the Carter W-1. WHY? (1) Relatively common (read cheaper than most anything else) (2) Carter metering rod technology (3) Leather accelerator pump (no issues with ethanol) (4) Parts availability is excellent (5) Cast-iron throttle body (no warpage) (6) Brass floats (7) All jets (idle, pump, and main) are all removable/replacable (8) Mechanical power circuit (much easier tuning) Carter produced 128 different type W-1 carburetors. For multiples, we suggest numbers 420s, 483s, and 574s. If the 420s is used, all carbs should be 420s. The 483s and 574s may be used as either mix or match. Original applications: 420s (1939~1940 Chevrolet) 483s (1941~1942 Chevrolet) 574s (1946~1948 Chevrolet) CFM: The only person that truly understood CFM ratings was Mark Twain ("figures don't lie, but liars figure!"). The venturii area of any of the 3 W-1's listed above is 1.23 square inches. Compare that to 1.38 square inches for the Holley AA-1/2100DD commonly called the 94. So one of these single barrel carbs has approximately 11 percent less area than the venturii area of the 94 two barrel. Tuning: Since Carter produced 128 different type W-1 carbs, if different calibrations are required, GENERALLY different jets (idle, pump, main) and different metering rods may be acquired from used donor carbs; or all are currently available new. Since the power circuit is mechanical, the lower levels of vacuum often associated with multiple carbs does not effect the operation of the power circuit. The mixture of the power circuit is controlled by the diameter of the tip of the metering rod. And while we have never to date had to adjust the timing of the circuit, it may be adjusted by bending the mechanical operating rod. Disadvantages: The only disadvantage of which I am aware is the lack of intake manifolds drilled and tapped for the W-1. It may be necessary to fill stud holes, redrill, and retap for the W-1. Jon
When posting my initial post, I forgot this link: https://www.thecarburetorshop.com/CarterChevroletW1.htm Among others, the 420s, 483s, and 574s are all pictured, with some identification information if the tag has been removed. Jon
IMHO it needs to be a tripple setup or single on an inline 6. Dual setups work to some degree, but if you looking for real gains you want 3 independent (not on a common intake) carbs, because of flow dynamics and valve events etc. Just like the GM engineers figured out on the Corvette. I was looking into Harley carbs, and also into some more exotic stuff for this lately. There are many interesting possibilities out there, if you want to think outside of the box. For a more traditional setup and if you care about period correct, I agree with Carb King, the W-1 is the way to go.
Weber, DCOE and others since pre war, SU , old as dirt, comes in many sizes , as long as you can grasp the concept of "needles" they are great, I wouldnt have any problems finding multiple old Weber or SU cardbs than ever finding one Carter W1. Triple SU's look great as well. Im a bit of a sidedraft fan. (photo my '55 Holden)
A set of side draught Webers on a well tuned engine does sound and look very nice. Not sure how period correct they would be, when did they start making those?
They started importing Weber carburetors to the US in the early 50s, but are commonly remembered as the carburetors on the Grand Sport Corvettes, and the Cobra Daytona coupes that raced at LeMans in the 60s. https://www.jiminglese.com/weber-history
I've found a reference to sand-cast 50DCOs — ancestor of the DCOE — being fitted to a Maserati in 1931. I have not been able to verify it. Edit: another website shows a "1931 50DCO" with a much taller float chamber and a different mounting flange: https://240260280.com/Tech/Carbs/Weber/DCOE Theory Operation and Tuning.html The other setup worth mentioning is three SUs.
I find it quite interesting that our non-U.S.A. members mention S.U.'s and Webers. I suppose in some non-U.S.A. areas the W-1's are less than common. Here, they are at least as common as the Holley AA-1's, and today more common than original Stromberg EE-1's ("original" in this case referring to those produced by the Stromberg Division of Bendix in the 1930's, and 1940's). While I like S.U.'s and have tuned hundreds of them over the decades, I would hate to try to source three matched decent ones of any size here in the U.S.A. As they say in the cowboy movies, many of them have been "rode hard, and put away wet". If you have S.U.'s in decent condition, tuning is quite easy other than sourcing the needles; which I could make if necessary. Used to have to machine about half of the S.U.'s when I was still doing them, as the piston housing warped, preventing the piston from functioning normally. As to the Webers, will say only that personal experience with aftermarket Webers has NOT been good, and they are certainly not in the same price league, let alone ballpark, as the Carter W-1's. Jon
That's a triple 1 3/4" SU setup on my avatar HA/GR on a 138cu.in. Holden. Some people ask why such large carbys for small displacement? Because they are a vacuum operated carby, the engine will only use as much fuel as it will handle and don't fuel up. Thanks Jon for the technical info and you're correct. Other countries don't have the ready supply of Carters.
My drag altered roadsters usually get 3 twos. But a good economical carb setup for the street/strip is two 2150 Autolite 2V. Period correct too.
Question: years ago (mid-60s???) There was an article in Hot Rod Magazine where they used multiple Tillotson HR and HD carburetors on a Ford 6 with the cast on intake manifold. As little as I can remember it, whomever did it machined 4 holes in the side of the casting and welded or brazed stubs with flanges to bolt on the carburetors. My question is, how would you get pumper carbs like that to work on a multi-cylinder 4-stroke engine? And how would you get rid of the stumble on wot, with no accelerator pumps? And get the fuel mixtures given adjustable low an high speed jetting on each carburetor? Okay so 3 questions...
As an aside, this was the more usual multi carb setup for the Falcon six: The awful log intake gets a hole bored at each end and this whole rig is somehow scabbed onto it. I've never run it or tried to modify an intake/cylinder head to fit it. It should really improve fuel distribution in that terrible log intake.
I believe you're referencing a 1967 HRM article by Ak Miller about modifying a Ford 200. I think that he ended up with four Honda motorcycle carbs on it.
Image of float-less "carbs" / Injectors(?) on a GMC 6. Parker Bohn once drove a '36 Chevy coupe on a local (New Egypt, NJ) Speedway. The car was #659. I recall him racing while I was in the military, stationed at the 46th A.D.M.S. (BOMARC) missile site.
The Jalopy Journal
