Strange timing issue - '68 318

cooling usually isnt a issue on a street engine alot of built engines dont run VA without problems, Ive tried both on mine if a 1/2 a gallon better makes you feel better than leave it hooked up. He originally checked timing with 10 degree with advance hooked up, Im saying thats too low thats why I said crank it up to check it but not with vacume advance connected, sorry for any misunderstanding.