R2

R2 Carbs

Carter 3507s, 3588s, 3725s (pressure sealed) - 1-7/16" primaries, 1-11/16" secondaries

Calibrated and sealed - Studebaker Part# 1561641


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flow 625 - 637 CFM (@2" hg)


(Note:Carter #3507S,is an R2 Carburetor. It's the # that crossed to Stude#1560338


(Aug 95 TW) Front jets 120-162 / .103
(July 2005) Front jet is equivalent to a .101 Edelbrock. Rod is an odd size 76/45.
( I currently run my car with .101's and 75/47)
16-263 is shown as the correct rod for carb#3507S, R2 Carburetor. That is the Carter # and crossed in my book to Stude#1560338. ( Erizzolo) Replacement Carter CRT-9635 or Edelbrock 1406 (Use Marine version or get kit to seal accelerator pump)

• " I finally grabbed an old AFB and tried the new style carb top gasket on it and it's the same ! I swapped all the new stuff over to the old top casting. Now I have modern AFB's bottom with the old style top that fits the bonnet correctly.
  I kept all the new stuff when I did the swap and I have the "strip kit if I need to rejet. BTW, I used an old AFB core off a GM car instead of a Avanti core. You may need to adapt the electric choke to work with the old top. With the carb I had, it just needed some bending to match up.
  I can tell you the top swapped fine, you even end up with the fuel line in the right place. I moved the floats and needle and seat to the old top. You may have have to mess with the choke linkage though. From what I can see the only difference in the new top is the neck and choke plate. It runs just fine, as I would expect it to, nothing in the fuel circuit has been changed, just had a new roof put on Just to be sure your carb is the same, compare the old and new gasket.
  My old top had a small vent hole just below the top center screw in the back, you need to plug it.

Sep 2006
After a couple of years tweaking the Edelbrock/AFB combination, it (the above) is rather simple but requires the venturi clusters to be changed and the air valve modified. All very simple stuff but performance and mileage improve drastically with these changes. Ernie R
R2 R5388

A year or so ago, I researched jet and rod sizes for my 3588S; with an eye to leaning the primarys. These are notes I saved. If you have a 3724S, it's different. I'll look for stock sizes for it. There is some good information at VS57.com, under "Tech Ref". There's also a chart of jet and rod sizes for the old style part #'s, in "Avanti Magazine" Fall/Winter 2003, issue 124.

The standard '64 Avanti R2 primary jets from Stude were .1015, with .076 X .049 rods.
First step lean R2 was the same jet with .077 X .0515 rods.
R2 secondary jets were .0935.
Standard R1 primary jets were .089, with .069 X .051 rods.
R1 secondary jets were .070, I think.

The original primary jets and rods, from Stude, were larger than are available now. You can subtract rod cross sectional areas from jet area; and find combinations of currently available jets and rods that give similar totals, richer, or leaner. A programmable calculator would save time. As far as I know, the new jets fit. The top of the rods may be different and require modification to the lever they hang from. Summit Racing has handy charts of available jets and rods, and their sizes.

Jets:
Summit Jets

Metering Rods:
Summit Rods

For one step leaner than stock, on my R2, I figured EDL-1426, .095 jets; with EDL-1449, .070 X .037 rods.

For two steps leaner, same jets, with EDL-1455, .073 X .042 rods. Rods can be changed on the car, without removing the airhorn.

Five bowl/airhorn gaskets are EDL-1499.

Step up spring assortment is EDL-1464.

Marine accelerator pump, with seal for R2, is EDL- 1471; $22.69.

Inlet needle and seat, .110 size, is EDL-1466.

Mike M. (Jan 2007)