Here is the difference
02-03 mach 1 and cobra heads
this was the first run of the mach1 and cobra heads, after a million complaints about excessive noise in the valve train on the drivers side ford figured they had to do something so they revised the drivers head. When the car came on to the service drive the first thing the service writer does is run TSBs to find any open complaints and the drivers head had a TSB for noise so ford started replacing them well about 2-3 months in to this they found out that they were redoing some of the cars that had already been don’t so the change the head by having then painted with a blue strip. Now this has no reworking other than some different valve guides but in fords attempt to keep the technicians from double dipping they painted the service head blue so the service writer knows if the TSB had been done or not. This head was the first head and only has 4 spark plug threads
mid 03 to end of 03 cobra and mach 1 heads
This is the 4V head that has been painted with a blue strip to show this is what ford though would take care of the excessive noise from the valve train (little did ford know that the piston slap was the cause for this noise) way to go ford !!!
This head also possesses 4 sparkplug threads
11/15/2003- 4/2004
This was the first 9 thread head
this was the 2004 cobra and the mach 1 head for 2004 this head was completely different. This was the last revision head also known as the FR500 replacement head. This head was issued some time after 11/15/2004 I have confirmed this with every 2004 cobra and mach 1 I have ever touched (approximately 50-60 cobras and 20-30 mach1s ) this head has improved ports also the coolant passages have also been changed. The only way to tell what head you have is by the thread count in the head. 9 thread signifies you have the 2004 heads and 4 thread signifies you have the 2003 heads (while nonpainted 2003 heads notes early 2003 heads) Now there is an easy test to see what heads you have seeing as how all of the threads are at the bottom coming up you can perform a simple thread count test. Start from the tight position and count the number of turns it takes to remove the sparkplug 4-5 turns means you have 4 thread and 8-9 turns means you have the 9 thread heads. if you are buying heads keep this in mind or simply contact me to buy new heads 9 thread with the improved passages 1500 a set complete new
FR500 heads
Now these heads are a little different, the installed “FR500heads” the ones that are on the 2004 cobra and the mach are from the ford line , Ford racing has came up with there own FR500 line that uses longer valve stems, different cams and different followers as well these were only available from the ford racing catalogue. (They are some nice heads but not worth the money when you can take a set of 04 heads and port them with 1mm over size valves to achieve better results) if you get a ford racing catalogue you can buy the entire FR500 kit so that you may too change your stock heads to FR500 heads it comes with all of the followers, all of the valves, springs and cams, along with everything needed to make the swap and that goes for 1700.00- 1800.00
Now the facts
I have been in heated discussion after discussion about this. And please bear in mind I have done my home work, so much that I was able to prove LDC the cooling mod people that they were wrong when they tried to say there was no 9 thread heads ever on the 4v motor from the factory. All I tell you is do a simple thread count test that I have listed above and you too will find out that I am correct in this matter. So here are the facts all of the 4v heads built 2002-2004 are all good heads and produce good power, If you are looking to buy heads used or new the 2004 heads are worth more than the 2003 heads however I can get you new ones (2004 9 thread complete heads) for 1500.00 plus shipping. If you figure a valve job is 800.00 on the DOHC heads and if you buy a used set for 800.00 that means you just paid 1600.00 for a set of used heads when you could have had brand new ones. Just a little heads up
02-03 mach 1 and cobra heads
this was the first run of the mach1 and cobra heads, after a million complaints about excessive noise in the valve train on the drivers side ford figured they had to do something so they revised the drivers head. When the car came on to the service drive the first thing the service writer does is run TSBs to find any open complaints and the drivers head had a TSB for noise so ford started replacing them well about 2-3 months in to this they found out that they were redoing some of the cars that had already been don’t so the change the head by having then painted with a blue strip. Now this has no reworking other than some different valve guides but in fords attempt to keep the technicians from double dipping they painted the service head blue so the service writer knows if the TSB had been done or not. This head was the first head and only has 4 spark plug threads
mid 03 to end of 03 cobra and mach 1 heads
This is the 4V head that has been painted with a blue strip to show this is what ford though would take care of the excessive noise from the valve train (little did ford know that the piston slap was the cause for this noise) way to go ford !!!
This head also possesses 4 sparkplug threads
11/15/2003- 4/2004
This was the first 9 thread head
this was the 2004 cobra and the mach 1 head for 2004 this head was completely different. This was the last revision head also known as the FR500 replacement head. This head was issued some time after 11/15/2004 I have confirmed this with every 2004 cobra and mach 1 I have ever touched (approximately 50-60 cobras and 20-30 mach1s ) this head has improved ports also the coolant passages have also been changed. The only way to tell what head you have is by the thread count in the head. 9 thread signifies you have the 2004 heads and 4 thread signifies you have the 2003 heads (while nonpainted 2003 heads notes early 2003 heads) Now there is an easy test to see what heads you have seeing as how all of the threads are at the bottom coming up you can perform a simple thread count test. Start from the tight position and count the number of turns it takes to remove the sparkplug 4-5 turns means you have 4 thread and 8-9 turns means you have the 9 thread heads. if you are buying heads keep this in mind or simply contact me to buy new heads 9 thread with the improved passages 1500 a set complete new
FR500 heads
Now these heads are a little different, the installed “FR500heads” the ones that are on the 2004 cobra and the mach are from the ford line , Ford racing has came up with there own FR500 line that uses longer valve stems, different cams and different followers as well these were only available from the ford racing catalogue. (They are some nice heads but not worth the money when you can take a set of 04 heads and port them with 1mm over size valves to achieve better results) if you get a ford racing catalogue you can buy the entire FR500 kit so that you may too change your stock heads to FR500 heads it comes with all of the followers, all of the valves, springs and cams, along with everything needed to make the swap and that goes for 1700.00- 1800.00
Now the facts
I have been in heated discussion after discussion about this. And please bear in mind I have done my home work, so much that I was able to prove LDC the cooling mod people that they were wrong when they tried to say there was no 9 thread heads ever on the 4v motor from the factory. All I tell you is do a simple thread count test that I have listed above and you too will find out that I am correct in this matter. So here are the facts all of the 4v heads built 2002-2004 are all good heads and produce good power, If you are looking to buy heads used or new the 2004 heads are worth more than the 2003 heads however I can get you new ones (2004 9 thread complete heads) for 1500.00 plus shipping. If you figure a valve job is 800.00 on the DOHC heads and if you buy a used set for 800.00 that means you just paid 1600.00 for a set of used heads when you could have had brand new ones. Just a little heads up
...I've had the car on the dyno, and everything seems to be good!
How do you tell if you have 4 or 9 thread heads? ..just by the amount the spark plugs thread in??