Ok guys and girls, I need some advice on eliminating spark knock. At low speed the 389 with Turbo 400 likes to loaf along in third gear. When I hit the gas it has some initial spark knock, actually more like a rattle, it then downs shifts and takes off! The temp gauge is a little worrisome on these 90+ degrees days in NC... tops out at about 212 degrees, I'd rather it be 190-195 degrees. Anyway, the engine is the original 389 block, bored 30 over, Ram Air III heads, Hooker headers, Edelbrock intake Holley 600 cfm, mid-rpm power cam. Timing is set at 6 BTDC, which is the stock spec... as more advance just makes the spark knock worst. I've Added 2 bottles of STP octane booster to 93 octane gas. Any advice would be greatly appreciated. Thanks, Roqetman!