Short version - I blew up a power valve in my 6 pack (as evidenced by very rich with the usual smoke mixture screws having no effect) so I replaced that and wanted to go back to the beginning and get it all set correctly...anyway I set the outboard mixture screws (in the baseplate) to 1/4 out after seating them gently....running the engine I was able to adjust the idle on the center carb (with the OB carbs disconnected until I got max Vacuum. I brought the idle down to 900 - but the engine shuts off after idling....so I bumped it up to 1000 same thing. I am thinking the outboards need adjustment as well...I know this sounds stupid but do I again use the vacuum gauge? Are they not opened enough to help sustain idle? BTW No Vacuum leaks or issues. Timing was adjusted at 38 degrees all in just above the ping point with 108 Octane booster added...I am making around 11" of vacuum

Engine is a 500 CID:
intake exhaust
Duration .050 252 256
Separation 109
Gross Valve lift .573 .567
Heads received a Stage 2 porting and gasket matched the 6 pack intake to the heads. Heads were CC chambered to 73 CC Chamber and compression is now at 10.5:1 (the engine short block was from Indy and it came with dished pistons so the heads were taken down 60 thousand to raise the compression – the intake was also shaved to match the heads. – I have the paperwork for all that he did to them if you need it.

Center carb has the Promax metering block and a 35 squitter with 66 Jets and 50CC Pump. 4.5 powervalve

Outboard carbs have short yellow springs with the jet plate from Promax and 84 jets – the rear carb as a Promax base plate.

Read up on setting initial timing.

Total timing method is the lazy way to set timing. It doesn't usually get you close to what the engine wants at idle unless you win the lottery and get very lucky.

That build is going to want ~20*+ initial is my guess.