How many threads do the heads have for the spark plugs?
There has been much discussion over this. It was believed that all 2003 and all 2004 Cobras had 4 threads from the factory. And that only the latest heads (01/05) had 9 threads. New information now indicates that all 2003 Cobra have 4 threads, early 2004 Cobras have 4 threads, and 2004 Cobras built after some date in 11/03 have 9 threads. However, even these revised 2004 heads do not have the revised coolant passages found on the heads released in January, 2005. This is interesting information because there have been reports of spark plugs blowing out of the heads possibly in part due to the lack of sufficient threads and possibly also due in part to an improper installation of the plugs. I don’t believe there is any substantial proof that the 4 threads is a potential issue since the reported cases of blown out plugs is so few, but obviously having 9 threads is better than only 4. I have to admit that it is interesting that apparently Ford changed the number of threads at some point in
