by Carl Christiansen in the February 2003 RootesReview
Increased performance can be derived for the Alpine by changing to Weber carbs with several different options.
For general driving in town or on the highway I’d recommend the downdraught DGV or DCD carburetor. These are very simple carbs and adjustments are easily made with a change of the air or main (fuel) jet and or emulsion tubes. For those of you not familiar with Webers, the main jet allows the fuel/air mixture to be drawn into the choke/venture part of the carb from the bottom of the emulsion tube with the air corrector jet located in the top of the emulsion tube.
A noticeable improvement in low end torque and mid/top end acceleration should take place with a properly tuned DCD or DGV Weber installed over the standard carburetors installed on production Alpines. I personally have noticed a big improvement in all aspects of my 1725 Series V engine operation, from starting, thru idling to acceleration. Also, there should be an increase in fuel mileage by switching to the Webers over the twin Zeniths on the early cars, the Solexs on the Series IV or the Zenith-Strombergs on the Series V cars. In fact, while driving to Suni III in Montana I averaged 44.04 miles per gallon in an Alpine with a 1725 engine, equipped with a 28/36 DGV Weber, 3.89 rear axle ratio and overdrive! And, in spite of having a 3.89 axle, that was the fastest street Alpine I’ve ever driven. It took First Place (Personalized) in the Autocross with my 16-year old son driving.
The recommended conversion is either a 28/36 DCD or DGV unit but 32/36 choked units work fine also, especially for engines with oversized pistons and greater displacement. There is a good piece on the 28/36 DCD Carburetor in Chris McGovern’s book entitled “Alpine the Classic Sunbeam” on page 154 in the Special Tuning chapter and I quote, “This (28/36 DCD) was offered by numerous firms as a conversion for the late Series 3 and 4 Alpines fitted with the twin choke Solex carburetor. The advantage of this carburetor, apart from giving a noticeable increase in both fuel economy and performance, is that its base is identical to that of the Solex and therefore allows the carburetors to be interchanged using the existing manifold, thereby cutting down the cost of the conversion.”
Series IV manifolds are becoming more difficult to find. However, as a further improvement to the conversion is a new smooth runner manifold which eliminates the 90-degree turns of the older Series IV manifolds. These manifolds are imported from New Zealand and are reported to add another 3-5 HP. I have one of these units on another Alpine and I was amazed at the improvement in performance of this car when I converted from the Zenith-Stombergs to the 32/36 DCD with the new smooth runner manifold.
The recommended set-up for the DCD/DGV carbs are: F 30 emulsion tubes, main jets 140/160, air corrector jets 220/180, slow running jets 50/70 with a 70 pump jet installed. Other than the Weber Carburetor and manifold the only other piece necessary for the conversion is the throttle linkage. The old Solex linkage is a perfect fit and attaches directly to the throttle piece that comes through the firewall. Repro linkage kits are available if you have difficulty finding the original Series IV linkage.