@FWJ posted:The main issue with spark fouling is due to high cams producing not enough vacuum at idle speed. To overcome if everything else is fine (carburetor settings) is to rise idle rpm to anything between 1250 and 1550 rpm.
I know it’s ridiculously high but the only solution. I am hoping with dynamic timing setting in combination with an EFI the issue could be partially cured which allows a bit lower idle rpm as for the carby
With your Holley carb and the engine idling at 1250 to 1550, it would seem that you are no longer running on the idle circuit of the carb. Once off the idle circuit, the idle air bleeds are meaningless. I use the air bleeds to tune for maximum vacuum at idle and also tune for a lean idle to avoid fouling spark plugs. Running above the idle circuit can also result in the engine dieseling upon shutdown because the butterflies are essentially open.
A remedy for the above is to increase ignition timing at idle via vacuum advance or the Progression Ignition distributor (or something similar). The Progression Ignition distributor lets you simulate vacuum advance at idle within its software table.
Increasing ignition advance at idle lets you close the butterflies and thus run off the idle circuit and tune the idle air screws to lean out the idle.
I learned most of this while trying to resolve a dieseling problem on engine shutdown. It consumed much of my brain's available processing bandwidth for a week or two in order to stop the dieseling and fouled plugs.
The Progression Ignition distributor is essentially half of an EFI system. In the timing curve table, give it 25 (or more) degrees advance below 1000 RPM. Above 1000, give it a normal value starting at 16. Thus at idle, the advance is 25 and when you blip the throttle it instantly drops to 16 and then climbs as RPM's increase.