Jetting Webers
Jay Laifman (Jay_Laifman(at)countrywide.com)
Thu, 3 Dec 1998 08:31:20 -0800
Someone asked a couple of days ago about jetting the single down draft
Weber. I spent many weeks, perhaps months, working on the jetting on my
dual side draft Webers. I don't know what a dyno would say. But, I am
very happy with the drivability results. What I did was buy the Hayes
Weber book - which actually also had a section on Stombergs. In the back
they have charts on all sorts of cars and which Weber will work and what
jetting the factory used and what jetting they suggested for performance.
I found all the 4 cylinder cars using DCOEs and compared the jetting,
taking into consideration the size of the engines and if the cars had cross
flow heads or not. I then even looked at 6, 8 and 12 cylinder cars that
used DCOEs with one throat per cylinder and compared engines with similar
cc's per cylinder. From that I got a feel of the range of jets being used
and what might be right on my car. I played with that range and ultimately
found something that feels pretty smooth around town, and give plenty of
roar when I want it.
You might try that with the single down draft too.
Lastly, for what its worth, in "Alpine: The Classic Sunbeam", the following
are suggested for the Weber 28/36 DCD Carb:
Venturi...........26...............27
Main Jet........140............160
Emulsion
tubes..............F30............F30
Air Correction
Jet....................220............180
Slow running
Jet.....................50..............70
Pump jet..........70..............(no info was provided here - I am not
familiar with these carbs. I also wonder if there is a chance that the
slow running jet on the 27 is the missing number and the 70 there really
should have been the pump jet for the 27)
Good luck.
Jay