Thermoquad on 340 (plug photos)

The 440 carb should be big enough, and I've jetted up primaries, fattened secondaries by limiting the air door opening some from stock, added pre-load to the air door spring, drilled out the squirters, raised the rods to maximum recommended turns, and set the idle a bit rich. And the A/F #'s look fairly good.

Really has me scratching my head as to why the plugs look like it's lean!!!