Hello,
 I have read Kevin's remarks about the carburettors and I would like to add
 that the 'large' Edelbrock 1406 (600cfm) that I tried on my 409 was probably
 a bit of an excess for the engine. As my Carter was beyond repair I bought a
 1403 (500cfm, similar to the old Carter 3131/3249) and having enlarged the
 holes for the secondary throttle valves on the intake manifold (pls see
 
http://www.stefanopasini.it/Bristol_...nifold_Mod.htm
 for details) it now seems to work pretty well. The 1403 is cheap (I bought
 it for $200), its linkages are not as different from those of the Carters as
 the 1406 are, and has the advantage of an auto electric choke as well.
 Cheers
Stefano