Dan:

I've never tried feeding four engines from a single tank, but more than once I've fed two.

Some things that have not worked for me on multi engine feed from a single tank:

Both engines fed from a single fuel pickup/clunk using a tee.
Header tanks. Waste of time and effort - the engine still has to draw the fuel from the main tank.
Muffler pressure. In maneuvers the high engine goes lean and the low engine goes rich, both quit running.
Plain suction feed.

This way works:

Separate fuel pickup/clunk for each engine,
--- AND ---
Crankcase pressure with check valves and Cline (or similar) regulators.
--- OR ---
A Perry fuel pump on each engine. (This worked best of all.)

Hope this helps. Really think everybody with three or more engines is using a tank for each engine.

Bill.