High Flow port needed.July 20 2008 at 5:32 AM
Response to engine year
This Dizzy will not work like most do on low vaccume to give more advance.
Take a look at the rotor rotation.
With the car off, and dist. cap removed draw a vaccume. You will notice that the rotor will turn in the opposite direction of rotation. Which means it is advancing on High vaccume and retarding on low vaccume. Great for a turbo set up but not for carbs.
The 79/80 model year had such a small venturi and delay to open the secondary barrel that the manifold never saw a low vaccume condition. To over come this problem a port was installed just at venturi level. At high volume flows( High load and engine RPM) vaccume was created, which in turn advanced the timing of the engine.
I would only suggest that if you use this Dizzy with dual carbs ( 4 barrels) that you do not use the vaccume line and advance ( retard) system and set your timing to about 12 degrees advance and let the mechanical weights do the other 10 degrees or so.
TonyK Grimsby Ont Canada.