Will this part fit 78.5CC 3HP harbor freight engine ?
We have not confirmed compatibility with that engine, so we would recommend comparing the images of this ignition coil to your existing one to see if they match. The mounting hole distance is 56 mm center to center, we'd recommend comparing that measurement to the mounting hole distance on your existing coil as well to see if they match. If the images & mounting hole distance match your existing coil, this should be a compatible replacement. If you should order it and find that it is not compatible with your engine, we do have a 60-day return policy for items sent back in new/unused/undamaged condition.