Read my plugs.

[aaronk785]

This is a plug I just installed and removed after a test run. Test drive was about 16 miles at highway speed (60) and 4 wot runs through all three gears. Engine is a 408 10 to 1 comp. Solid cam 254 260 at .050 .565. .570 lift. Home ported speedmaster heads. 4500 stall 3.91 gears. Looks lean to me but I’m no expert. Oh. Preform 750 do 72 78 jets.

 

[George Jets]

☆☆☆☆☆

 

[Newbomb Turk]

What plug and heat range? I’m assuming pump gas.

I can’t see any fuel on those plugs. Have you verified the size of the main air bleed and the emulsion stack?