Reply to "spark timing"

There is a dash mounted adjustable advance made by MSD. That was one of the few MSD items that I really liked.
I don't know if it can be adapted to your ignition? Maybe?

http://www.msdignition.com/Pro..._Timing_Control.aspx

You should have tested the engine for maximum advance total and at what rpm that occurs.

34-36 degrees total all in at 4,000 rpm should not be any kind of an issue.

Every engine will be a little different. One might like 34, another 36.

The issue ususally is how fast the advance gets to the maximum.

On a drag race car total advance all in by 2,200 to 2,500 is optimizing the car.

In my experience you can not run that rapid of an advance with the pump gas we now have available to us.

An Edelbrock carb has a mechanical secondary. I don't like them. They have to be set perfectly to work right. It is very easy to have the symptoms of over carburetion with them as a result.

What you can do is disconnect the rod to the secondary butterflies, wire them closed so they can not open then run the car and see how it responds.

If it runs better up past 4,000, then that is pointing at the secondaries as the issue.

You need to read the plugs.

The color you are looking for on the electrode is a medium brown with a distinctive rust tint to it.

Get the plugs to look like that with just the primaries connected. Then work on the secondaries.

I don't know what the jetting should be on an Edelbrock. On a Holley that's a different story.

It could well be that you have enrichened the secondaries more that the engine can use.