What spark plugs should I use in my 440? It's a 9.5 -1 motor with about 475 HP at the flywheel. I said use AC 44s. Been using Autolite 2976 plugs for years but last night when I went to unload it from the trailer to put it into the shop bay for a tranny adjustment, it would not start. Had spark everywhere and had gas. Wouldn't even fire with starting fluid. Only got a few hits. Last time I drove it was onto the trailer after nine runs down the strip in the 12.19/12.25 et range. The plugs only have the nine runs on them. The guys at the shop says very likely the plugs are dead. Never heard of that one but I learn something new ever day. Akron Don Gallimore