Aftermarket carburetor adapters (original, or fabricate)

[carbking]

A question in another thread prompted this thread.

 

EDIT: I have problems doing a comprehensive article on this forum, so have placed this one, with pictures and other data, on my website. Here is the link:

 

http://www.thecarburetorshop.com/Aftermarket_adapters.htm

 

In the 19 teens and twenties, many carburetor companies made aftermarket carburetors for many applications for which they had not sold the original carburetor. As many companies either ignored, or blatantly defied, S.A.E. standards, it was necessary to sell a flange adapter with the aftermarket carburetor.

 

I have lists of adapters originally produced by Carter, Marvel, Rayfield, Schebler, Tillotson, and Zenith (and probably others). No, I will not publish these lists for a number of reasons; the primary reason being they would be mis-interpreted by many, and I would catch the flak!

 

How? These adapters were made to adapt a SPECIFIC carburetor to a SPECIFIC application. So a Zenith adapter to adapt a Zenith size 2 type 105 carburetor to a specific application MAY NOT adapt a Zenith size 2 type 63AW carburetor to the same application. Why? Because the 63AW is physically wider than the 105. So looking at any of the lists for a cross-flange size 2 to size 3 adapter would get an enthusiast a part number for an adapter that would bolt to the carburetor and bolt to the intake, but maybe NOT allow the carburetor to fit in the allotted space between the engine block and the fender.

 

So, the way we suggest to proceed.

(1) Determine which carburetor to use to properly run the engine.

(2) Determine which type of adapter will be necessary to adapt the carburetor to the engine:

   (A) straight

   (B) cross

   (C) rotated

   (D) offset

Each of these will be discussed in detail below

(3) Determine the dimensions of the carburetor with the adapter connected, and measure to see if it will fit.

 

Types of carburetor flanges:

 (1) straight - a straight line drawn from center to center of the mounting studs would run from bumper to bumper on the vehicle

 (2) cross - a straight line drawn from center to center of the mounting studs would run from fender to fender on the vehicle

 (3) rotated -  a straight line drawn from center to center of the mounting studs would not be parallel or perpendicular to a straight line from bumper to bumper. Good examples would be 1929~1931 Chevrolet 6 cylinder and virtually all single barrel Marvels produced after about 1925. The Chevrolet is rotated 30 degrees. The Marvel rotation varies.

 

Types of adapters:

(1) straight - the straight adapter will allow a carburetor with a straight flange to mount to an intake with a straight flange. Often this is quite easy. From a swap meet (or salvage yard if you are lucky enough to still have a salvage yard), acquire two unloved carburetors (we used Tillotson type JR, Holley 1904, and Rochester type B and BC) with cast iron flanges with the appropriate center to center spacing, place the throttle body in a power hacksaw such that the saw will cut the throttle body parallel to the flange just on the side of the throttle plate opposite the flange, acquire a short piece of steel pipe of the appropriate diameter, and weld it (or if you are me, take it to someone that CAN weld) all together. The completed adapter should resemble a capital letter "H" that fell over on its side. The cross-bar in the "H" is the pipe with an I.D. equal to the smaller of that of the carburetor or the intake. There must be sufficient distance between the legs of the "H" to allow nuts to be installed.

(2) cross - the cross adapter will allow a carburetor with a straight flange to mount to an intake with a cross flange. Theoretically, the reverse is possible, but cross flange aftermarket carburetors are very rare. Because of the orientation of the nuts, often a cross adapter may be made as above but without the pipe; just weld the two flanges together. 

(3) rotated - the rotated adapter will adapt a straight flange carb to a rotated intake manifold. Often, like (2) above, it may be fabricated simply by welding two flanges together.

(4) offset - the offset adapter, virtually always identified with Marvel applications may be necessary because using another adapter will cause interference with something (generator, steering box, etc.). The most common requirement for these is the 1926~1929 Buicks where one needs a rotated adapter WITH an offset. Basically, the offset is a small "S curve" in the pipe connected the two flanges.

 

When fabricating the adapter, remember that for updraft carburetors, the vacuum of the engine is required to pull the fuel from the carburetor UP into the engine. Therefore the adapter should be as short as possible, given space and strength requirements.

 

All of the above assume a two bolt flange. There were a few applications with 3, 4, 5, and 6 bolt flanges. The procedure is the same. S.A.E flange sizes (cheerfully ignored by Marvel, and some others):

 

Size 1 - center to center 2 3/8 or 2 7/16

Size 2 - center to center 2 11/16

Size 3 - center to center 2 15/16

Size 4 - center to center 3 5/16

Size 5 - center to center 3 9/16

 

Jon.

Edited June 21, 2018 by carbking (see edit history)

[edinmass]

Flange? Why bother with a flange, just use JB Weld,  it’s holding half the carburetors and fuel pumps together that I see every day. Sorry Jon, I’m just tired of people driving seven figure cars with the wrong components and parts, and too cheap to fix it right. They insist the car was “fine” the way it was......when they could get it to start. People,want help, ask for it, and then don’t listen anyways. I am SURE your familiar with this.......after all, all carburetors are the same if the look alike. 

[carbking]

Ed - you may appreciate this one:

 

A month or so ago, sold a rebuilding kit for a Stromberg UX-4 (exceptionally rare carb). Last week, customer emails that the needle and seat won't fit? Checked the prints, and ALL of the UX-4 carbs take the same needle and seat. Emailed this information. He called, and we had a great conversation, the result being he would send his "original" needle and seat and the one I had sent, and I would modify to fit his carb.

 

Well, when I received it, was like what the????? Fortunately, he also sent the carburetor bowl and float. Sometime in yesteryear, someone cast a new bowl assembly, and did a really nice job; BUT, they used a Stromberg U-2 float and a TILLOTSON fuel valve!!! They modified the float pin placement in the bowl to accommodate the Tillotson fuel valve, and U-2 float! WHY would someone spend the funds to cast a new bowl assembly and then not machine a new float valve???

 

Anyone, I am duplicating the Tillotson valve, with a large enough orifice for his engine.

 

Even better than JB-weld

 

Jon.