was running a 750 cfm carb, it was too much. Put on a 600 and i'm not sure if it's enough. Plugs are alittle white so i know it's runnig lean or the plugs are the wrong heat range. Yall think i should try a colder plug or step up to a 66 or 67 jet, it has 65 right now. thanks.

 

what is the engine?
big drop from 750 to 600.
I would start with jets

how does it run through the rev range?
mine was running lean and whiting the plugs like that (engine has some goodies, but not psycho)
the biggest give away was running out of steam over about 4800rpm.
adjusted the mixtures and went up one jet size (but couldnt tell you what size). the carb is a 650 Holley DP.
now pulls 5500 before dropping off and plugs are brown.

dunno if that helps.