Re: 1956 Clipper Hot Rod

Posted by Owen_Dyneto On 2008/10/20 22:38:05

John, the 55 and 56 dual Rochesters are quite different. The 55 has an antipercolator valve on the float chamber, in 56 it was an internal vent. In 56 they added a set of air velocity-activated baffle valves in the secondary that only allowed the secondaries to function when there was sufficient air flow. The 55 and 56 duals had different main jet sizes, and as well the single Rochester 4 bbl was jetted differently that the 2 x 4 Rochesters. For example, the single Rochester-equipped 5680 had primary and secondary main jets of 0.052 and 0.065, whereas the dual setup had 0.048 and 0.054. I believe the corresponding numbers for the 55 Caribbean were 0.050 and 0.058.

Craig, you're certainly right that setting 4 idle mixtures is a bit tedious and I really don't know if the GM or Packard-recommended sequence makes it any easier or not. But simply getting easy access to the mixture screws is also a pain, especially the rear left.