Reply to "Bad brakes"

Plumbing of the vacuum at the manifold are -8 Earl’s fittings.
90 degree at cylinders 4 & 8, both feed forward individually to a tee on top of cylinders 1 & 5, then across the front of the engine & tee into the original supply line.
Supply line goes up to the front area, into an Earls check valve, then a vacuum bottle, then into the twin diaphragm booster which has its original check valve.
(Ran this twin diaphragm booster when I had the Holly carbie & had heaps of vacuum & great brakes).
Now the intention is to fit a Hella vacuum pump which also draws on the vacuum bottle.
Fit a switch into the bottle which senses vacuum, switches the pump on at 15 hg & off at 22 hg.

Question: Both the vacuum pump & the engine drawing on the vacuum bottle.
When the pump is on it will draw close the engine supply check valve?
So with this setup, will it ever actually be using engine vacuum?

I am having issues with fouling plugs when idling for extended periods of time.
Then the engine starts to mis-fire.
This is I think more about getting the butterflies synchronized.
Last time I drove it I was fouling plugs, (NGK BCP5E S) on cylinders 5 & 6 which I believe these 2 butterflies must be slightly closed compared to the others, reducing air flow & thus running too rich on those cylinders.
I need to play with the air-bleed screws more for the idle, instead of relying so much on the idle screw on the butterflies.

New set of coil packs are on their way as originals are old & going to fit a set of Bosch Iridium plugs & see if I can get a better spark.

Regards,
Tony.