Dont want to hijack this thread, but I have the same question, same engine, perhaps the same use.

I currently have an old edelbrock 1406 on a edel high perf intake manifold. Neither myself or another old school mechanic can get it tuned just right.

So I have been looking at alternatives, get another rebuilt 1406, try to rebuild it myself, or look at a holley.

On other forums I have seen folks say that a vacuum secondary is the best thing since sliced bread. I dont believe that the 1406 has a vacuum secondary but the holley O-80570 does.

The question is Are vacuum secondarys better in a street/mild performance engine better?


Thanks!