by Carl Christiansen in the March 2003 RootesReview
The Alpine engine is a very robust unit and without much loss of fuel consumption road tests can be made competitive. Like most race engines the power is made in the head and the Alpine head can make horsepower! Alpines racers in England are making 150 HP at the rear wheels. That’s a lot of HP! However, 150 HP on an engine dyno is possible over here in the States as well.
Anyway, this article is about using the 40 DCOE Weber carburetor. This carburetor is really designed for a high compression, free revving race engine. This carburetor will give the Alpine engine all the “go” it wants. I’m running a set of early 40 DCOE’s without the air hole in the face where the air cleaner mounts; rather, the air compensating holes are in a “castle” which is under the emulsion tube cover. I’m using F2 emulsion tubes with a 180 air corrector and a 145 main jet. I’ve also been able to find and use 36 mm choke tubes, which are somewhat hard to find for the 40 Webers. That is the largest choke made for the 40 DCOE.
It’s very important to provide your race engine with enough fuel/air mixture to let it breathe when it’s trying to accelerate so “flowing the head” is equally important. The 40 DCOE carburetor was initially an after-market product of Jack Brabham, who also used to race Alpines. In Chris McGovern’s book entitled “Alpine the Classic Sunbeam” on page 155 of the Special Tuning chapter he describes the twin 40 DCOE Weber set up as: “This must be considered the ultimate in carburetor conversions marketed for the Alpine and is a must if you are considering using your Alpine in competition. Jack Brabham first marketed this conversion for the Series 2 Alpine. It increased performance tremendously, show that Brabham’s conversion under test conditions returned better fuel consumption than that of the standard Series 3 Alpine. However, like all other complex machinery, the DCOE must be looked after and set up correctly to obtain the best results.”
Setting up the 40 DCOE Weber carburetor used to be a task, but not so anymore. There’s a Speedpro Series of books written by Des Hammill entitled “How to Build & Power Tune Weber & Dellorto DCOE & DHLA Carburetors” that makes it a snap. This easy to understand book is spot-on with info on the 40 DCOE Weber. I used it to correctly set up my carbs so that even after eleven runs on the dyno, changing everything from emulsion tubes to jets, etc. the engine made the best power & torque with what “the book” said my engine needed. How easy is that!
If you’re racing an Alpine, consider using the 40 DCOE Weber set- up. You’ll like the performance. Some race groups don’t recognize the correctness of the 40 DCOE carbs on the Alpine engine, but Chris McGovern’s book might be enough to convince them. They were used as an aftermarket option when the Alpine was racing in the ‘60’s. Better still, if you have documentation that your car used to race with Weber’s you have proof of its historical significance.