[FED 387]

try any other coil other than another a MSD 8261 if you are going to run more than a lap every hour or two just to see if that is the problem--- for repeat operation much like stock/super stock/ bracket cars go DO NOT USE the MSD 8261 it will usually do what you are describing---an MSD 8251 will not cause the symptoms you are describing---an MSD8261 coil gets so hot internally with repeat operation it breaks down due to the heat--- if you ran the car for a lap then shut it down for a while say 30 +minutes then ran another lap you MIGHT be OK but the MSD 8261 coil is not designed for lap after lap