[NickRCarter]

Hi there, I have a SBC 383 with 750 Holley. The cam is an Isky Mega hyd race cam, Canfield heads and MSD 6AL. The engine is in A GD 427 weighing 1086 kilos.
So far I have been able to get the secondaries to operate, despite using the lightest spring (yellow). The diaphragm is in tact and the system seems to operate correctly as far as I can tell by operation of the rod and diaphragm by mechanical testing ie the secondary butterflies are free to move once the primaries have been throttle advanced by say a 1/4, and the air/vacuum route to the primary venturi seems OK.
Can anybody give me any pointers as to why the secondaries are not moving at all! I have confirmed this with the use of a paper clip on the actuating rod.
Nick