Garys1969RR
Well-Known Member
Usually black spark plugs indicate an over rich condition. On my 451, 509 cam, Street Dominator intake, 915 heads, I have a 3310 Holley. Am using 72 primary (stock) and 80 secondary. (Stock sec is 76.) And now using a purple sec spring. Had a yellow one, but it would bog. Now with the purple one it doesn't bog when the sec open. I think you should limit your dist. centrifugal advance to 18 degrees. Then start with 18 to 20 initial advance, and 38 total by 2500 RPM. This will help low end even more. Thats what I'm running, and it works great!
