Rough idle- low vacuum

[72SB]

OP. I have a BPE and the Edelbrock 1406

You absolutely need VA hooked up to manifold vs timed vacuum on carb. You will then need to back off "base" timing as it will provide some timing advance at idle. Yes I know the Edelbrock 411 says use timed...they have to say it, emission thing.

You need to nail timing before final carb adjustments, or you will be chasing your tail. Assuming your damper timing marks ae correct in relationship to your pointer (read I had to get a different pointer for my BPE than my original 327). Pointer is based on what size damper you have. My BPE came without manifold, carb, dizzy and accessories.

You want 20-24 degrees of timing at idle WITH VA. Depending on how much VA your distributor VA provides at X rpm, you adjust "base" timing accordingly. Lets say the VA provides 10-12 degrees of advance at idle so you would then want 10-12 degrees of "base" timing (at idle no VA). Yes its a deeper conversation on controlling how much and when VA applies and stops but for base settings, shoot for 20-24 degrees of advance, with VA connected to manifold vacuum on carb (lower port).

Then adjust the idle mix on carb. You want to be closer to 1 1/2 turns out. Adjust either way from there to achieve the most engine vacuum. Then adjust idle. If automatic, likely about 750 as putting it in ger will lower idle from trans load. Manual trans, 650 should work but just adjust accordingly

You just don't have enough timing at idle without VA.

nailing the VA involves using an adjustable VA and a detent plate to restrict how much it applies. Different conversation. You can buy adjustable VA but detent plate, not any more. Crane used to sell the kit. Home made version of stop plate is doable

Understand not using VA on a street car reduces gas milage, loads up plugs, motor runs rich at part throttle use (read 95% of normal drivin conditions)