Need Opinions and Advice on ‘03 Cobra Build

[03_Zinc_Termi]

So Im in a bit of a situation with my ‘03 Cobra at the moment. Need opinions and advice. I have searched through many forums found a ton of useful info on the matter but still need some opinions/advice like “What you would do?”

I apologize in advance for the long post, thank you if you actually read it and give your input.

So from the beginning, my car had a misfire on #8 due to no compression which i thought originally was from a hole in the piston after looking down in the cylinder (could have swore i saw a hole). So I had made plans to have a built shortblock done etc but once I got it apart I found that #8 had dropped a Valve Seat and was loosing compression through it. Ill add that cylinder #8 also has a timesert installed and to me it appears to be threaded way too deep into the combustion chamber (sticks out really far). So as of now I do not plan to reuse the head, I figure ill replace it while its off since it is a 4 thread anyways. So now that I know my shortblock wasn’t the issue (hopefully) and with only 50k miles I plan to reuse it. Now my issue is with the heads, Im sure anyone whose been around Terminators long enough has probably heard at least a million times about the “4 thread vs 9 thread heads”. So according to the many forums and research I have done I found that the heads were built in this order. Hopefully this information is correct because there is a ton of different info from different people stating different things regarding ‘03-04 Cobra heads.

“The earliest heads had casting numbers that ended in -"AF" and "-AG" with a major revision in '03 that ended in "-DA" (all four-thread plugs). The newer '04 heads with the nine threads end in "-DB" with the final revision in '05 ending in "-DC".

The “DC” heads supposedly addressed the cooling issue etc and are the ones to get when buying heads from what I understand.

Once I removed my heads I noticed that I had an “AG” head on the passenger side and a “DA” on the drivers with a blue stripe on its intake side, I assume meaning that my drivers head had been serviced at some point. I was told the blue paint was for dealerships to know the head had already been replaced/worked on, but honestly who knows why its there. Some say it’s completely irrelevant. Anyways both heads are 4 threaded heads and I plan to replace the drivers side head instead of having it rebuilt and using it again with that timesert. I also saw that a rocker arm had come off on cylinder #8 on the same valve that dropped the seat.

So now that Ive decided to buy another drivers side head at minimum Im finding that good shape “DB/DC” 9 thread heads can be had for around the same price as rebuilding my current 4 thread heads. Question is should i just buy a 4/9 thread replacement head for the drivers side and have the 4 thread passenger head rebuilt with it (keep passenger side with a 4 thread head) or buy two used “DB/DC” 9 thread heads and just upgrade both now while its apart.

I was quoted by a local shop that it would cost $429 per head and I buy parts. Head rebuild kits seem to go for around $800. So you figure $429 x 2 = $858 (headwork) + $800 (parts) = $1,658 and thats IF i reuse my Drivers timeserted head. Add another $500 to that if i replace just the drivers head. Granted after all that Id still have 4 thread older model heads. Id be at about $2100-2200 all said and done according to my math. I can get a set of decent used “DB/DC” heads for about $2k but they wont be rebuilt.. I have found a few with very low miles though.

What would you do?


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[speedoflife]

Quick question: shouldn't that DB head you have (driver) be equipped with 9 threads? Is it a DB with 4 threads?

I thought the DB were all 9 threads.

 

[03_Zinc_Termi]

Quick question: shouldn't that DB head you have (driver) be equipped with 9 threads? Is it a DB with 4 threads?

I thought the DB were all 9 threads.

Whoops! Thanks for catching that typo! Its a 4 thread “DA” head. My mistake


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[speedoflife]

You're at quite the crossroads.

A good set of low-mileage DB/DC heads is a great solution, but then you have to roll the dice as to whether you will have problems or not if you don't have them refreshed.

Rebuilding your heads allows you to upgrade components (valve seats/guides etc) and know that the heads are ready to go, but leaves you with an older design and 4 threads. And head rebuilds can get expensive if you decide to do any upgrading.

If it were me, honestly, I'd try to find a low mileage set of revised heads. They are getting harder and harder to find (at all - let alone clean) and if you are thorough you have about a 90% chance of being able to basically just throw them in the car. It will be more expensive but it will be an upgrade. Along with a head cooling mod, you will also be helping to prevent this from happening in the future. If you plan on keeping the car, I would go this route.

 

[03_Zinc_Termi]

You're at quite the crossroads.

A good set of low-mileage DB/DC heads is a great solution, but then you have to roll the dice as to whether you will have problems or not if you don't have them refreshed.

Rebuilding your heads allows you to upgrade components (valve seats/guides etc) and know that the heads are ready to go, but leaves you with an older design and 4 threads. And head rebuilds can get expensive if you decide to do any upgrading.

If it were me, honestly, I'd try to find a low mileage set of revised heads. They are getting harder and harder to find (at all - let alone clean) and if you are thorough you have about a 90% chance of being able to basically just throw them in the car. It will be more expensive but it will be an upgrade. Along with a head cooling mod, you will also be helping to prevent this from happening in the future. If you plan on keeping the car, I would go this route.

Exactly. Id rather be safe than sorry so to speak. These heads have 76k miles and are both DB heads. Extremely clean for $2100. Heres a link, pics are in the “description” part of the post btw.

https://www.ebay.com/i/182778589064


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[03_Zinc_Termi]

Also found these, completely gone through and replaced valve seals, didnt replace anything else. Heres a link. Which set of heads would be the best bet? Problem with this set is that the guy selling mainly only has feedback for “buying” items and not selling them so Im a little nervous to pull the trigger on them. He said the machine shop he took them too puts the blue stuff in the chambers, idk what it is though. Could be to check the seats? These are also DB heads

https://www.ebay.com/i/282649626032


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[speedoflife]

I can give you advice but it would be equally as informed as your opinion.
You're gonna have to wait for someone with a little more experience to weigh in for you.

I like the looks of the ones that have been reconditioned. But why were they rebuilt? And why selling now? Were they overheated to death and then repaired for resale? Or is this standard practice for the seller? They look great, but I have no idea what that blue stuff is. And pictures don't tell the whole story. Ever.

76k miles is relatively a lot, but those others look to be in good shape for the mileage. hotcobra03 has to have over 250k miles on his heads, if not more, so mileage shouldn't be a huge issue if condition is good.

Edit: And to add, that seller on eBay from Venice, FL has been selling salvaged Mustang parts for a while. They are a much more "known" entity, so to speak.

 

[03_Zinc_Termi]

I can give you advice but it would be equally as informed as your opinion.
You're gonna have to wait for someone with a little more experience to weigh in for you.

I like the looks of the ones that have been reconditioned. But why were they rebuilt? And why selling now? Were they overheated to death and then repaired for resale? Or is this standard practice for the seller? They look great, but I have no idea what that blue stuff is. And pictures don't tell the whole story. Ever.

76k miles is relatively a lot, but those others look to be in good shape for the mileage. hotcobra03 has to have over 250k miles on his heads, if not more, so mileage shouldn't be a huge issue if condition is good.

Edit: And to add, that seller on eBay from Venice, FL has been selling salvaged Mustang parts for a while. They are a much more "known" entity, so to speak.

Yeah hopefully someone chimes in. Id hate to buy heads and get stuck in the same boat again. The timesert makes me nervous or id just reuse mine. I mean if it’s honestly not a huge deal then i might reuse it but dont wanna deal with the plug issues in other cylinders down the road. I guess what Im saying is that i really dont wanna do this twice.

As for the Venice, FL seller, is he known for ripping people off? He said they were take offs that he just wiped down and cleaned up. Who knows how they looked before that. Im pretty sure they’re from a salvaged car, he knows little to nothing about them from what I’ve gathered.


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[NateDogg]

I recently did the same thing. I found a great set of DC cast heads for 550 shipped. I planned to have them worked anyway so i wasnt looking for a super low mile set. Ended up needing a valve job and had them cleaned and decked. Swapped the majority of my stuff over to the new heads.

The main thing I was concerned about when looking was the journals and stripped threads.

I can't remember the exact pricing for everything because alot of stuff was already purchased (cams springs ect ect ect)

If you have face book I'd recommend joining Todd Warrens tech page. Lots of good info and that's where I find mine.

Since your heads are off it would be a good idea to do arp studs/headcooling mod/cams if you were ever thinking of doing it down the road. That's what I did and couldn't be happier.

It gets expensive but you'll never have to do anything to them again!


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[NateDogg]

also I wouldn't trust that seller on Florida. I almost bought a set from him and they were trashed.

You're right. He pulls them at salvage yards from aviators.

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[03_Zinc_Termi]

Update:

Well after talking to a good friend of mine whose been working on Ford Mod Motors for the last 20 years I think Im going to keep my stock heads. He came over and looked at the timesert in cylinder 8 and said it looked pretty normal compared to the thousands of timeserts he’s installed over the years. He actually recommended that I install timeserts on all 8 cylinders of both heads since i have them off. It would be about the same as having the 9 thread heads. So after talking to him i did some more research and found that quite a few people have done exactly that instead of upgrading to 9 thread heads. Just get a cooling mod and your set from the sound of it.

Also I found a shop called “L&R Engines” based in California whose built a lot of motors for a few of the performance shops in my area, everyone seems to have nothing but good things to say about them. Derek (the owner) quoted me $3800 for a complete rebuild. It comes with brand new forged 2618 aluminum pistons (far better than stock), new rings, new bearings throughout the whole bottom end, and reusing my stock rods. The heads get machined with a 3 angle valve job etc. and new valve seals. We will be replacing the #8 valve and seat if needed. New Ford Racing Timing kit. Basically a complete rebuild with all needed machine work and parts. He said i can send him everything apart or together on a pallet and he’ll rebuild/reassemble it and send it back. For $3800 (minus shipping) it seems like a great deal to me and the fact that he has a good reputation just makes it even better. He also said that the timeserts would be a good idea while its apart. Anyone else ever had an engine built by L&R?


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[sigjig]

So Im in a bit of a situation with my ‘03 Cobra at the moment. Need opinions and advice. I have searched through many forums found a ton of useful info on the matter but still need some opinions/advice like “What you would do?”

I apologize in advance for the long post, thank you if you actually read it and give your input.

So from the beginning, my car had a misfire on #8 due to no compression which i thought originally was from a hole in the piston after looking down in the cylinder (could have swore i saw a hole). So I had made plans to have a built shortblock done etc but once I got it apart I found that #8 had dropped a Valve Seat and was loosing compression through it. Ill add that cylinder #8 also has a timesert installed and to me it appears to be threaded way too deep into the combustion chamber (sticks out really far). So as of now I do not plan to reuse the head, I figure ill replace it while its off since it is a 4 thread anyways. So now that I know my shortblock wasn’t the issue (hopefully) and with only 50k miles I plan to reuse it. Now my issue is with the heads, Im sure anyone whose been around Terminators long enough has probably heard at least a million times about the “4 thread vs 9 thread heads”. So according to the many forums and research I have done I found that the heads were built in this order. Hopefully this information is correct because there is a ton of different info from different people stating different things regarding ‘03-04 Cobra heads.

“The earliest heads had casting numbers that ended in -"AF" and "-AG" with a major revision in '03 that ended in "-DA" (all four-thread plugs). The newer '04 heads with the nine threads end in "-DB" with the final revision in '05 ending in "-DC".

The “DC” heads supposedly addressed the cooling issue etc and are the ones to get when buying heads from what I understand.

Once I removed my heads I noticed that I had an “AG” head on the passenger side and a “DA” on the drivers with a blue stripe on its intake side, I assume meaning that my drivers head had been serviced at some point. I was told the blue paint was for dealerships to know the head had already been replaced/worked on, but honestly who knows why its there. Some say it’s completely irrelevant. Anyways both heads are 4 threaded heads and I plan to replace the drivers side head instead of having it rebuilt and using it again with that timesert. I also saw that a rocker arm had come off on cylinder #8 on the same valve that dropped the seat.

So now that Ive decided to buy another drivers side head at minimum Im finding that good shape “DB/DC” 9 thread heads can be had for around the same price as rebuilding my current 4 thread heads. Question is should i just buy a 4/9 thread replacement head for the drivers side and have the 4 thread passenger head rebuilt with it (keep passenger side with a 4 thread head) or buy two used “DB/DC” 9 thread heads and just upgrade both now while its apart.

I was quoted by a local shop that it would cost $429 per head and I buy parts. Head rebuild kits seem to go for around $800. So you figure $429 x 2 = $858 (headwork) + $800 (parts) = $1,658 and thats IF i reuse my Drivers timeserted head. Add another $500 to that if i replace just the drivers head. Granted after all that Id still have 4 thread older model heads. Id be at about $2100-2200 all said and done according to my math. I can get a set of decent used “DB/DC” heads for about $2k but they wont be rebuilt.. I have found a few with very low miles though.

What would you do?


SEE PICS BELLOW

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Update:

Well after talking to a good friend of mine whose been working on Ford Mod Motors for the last 20 years I think Im going to keep my stock heads. He came over and looked at the timesert in cylinder 8 and said it looked pretty normal compared to the thousands of timeserts he’s installed over the years. He actually recommended that I install timeserts on all 8 cylinders of both heads since i have them off. It would be about the same as having the 9 thread heads. So after talking to him i did some more research and found that quite a few people have done exactly that instead of upgrading to 9 thread heads. Just get a cooling mod and your set from the sound of it.

Also I found a shop called “L&R Engines” based in California whose built a lot of motors for a few of the performance shops in my area, everyone seems to have nothing but good things to say about them. Derek (the owner) quoted me $3800 for a complete rebuild. It comes with brand new forged 2618 aluminum pistons (far better than stock), new rings, new bearings throughout the whole bottom end, and reusing my stock rods. The heads get machined with a 3 angle valve job etc. and new valve seals. We will be replacing the #8 valve and seat if needed. New Ford Racing Timing kit. Basically a complete rebuild with all needed machine work and parts. He said i can send him everything apart or together on a pallet and he’ll rebuild/reassemble it and send it back. For $3800 (minus shipping) it seems like a great deal to me and the fact that he has a good reputation just makes it even better. He also said that the timeserts would be a good idea while its apart. Anyone else ever had an engine built by L&R?


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Whoops! Thanks for catching that typo! Its a 4 thread “DA” head. My mistake


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So Im in a bit of a situation with my ‘03 Cobra at the moment. Need opinions and advice. I have searched through many forums found a ton of useful info on the matter but still need some opinions/advice like “What you would do?”

I apologize in advance for the long post, thank you if you actually read it and give your input.

So from the beginning, my car had a misfire on #8 due to no compression which i thought originally was from a hole in the piston after looking down in the cylinder (could have swore i saw a hole). So I had made plans to have a built shortblock done etc but once I got it apart I found that #8 had dropped a Valve Seat and was loosing compression through it. Ill add that cylinder #8 also has a timesert installed and to me it appears to be threaded way too deep into the combustion chamber (sticks out really far). So as of now I do not plan to reuse the head, I figure ill replace it while its off since it is a 4 thread anyways. So now that I know my shortblock wasn’t the issue (hopefully) and with only 50k miles I plan to reuse it. Now my issue is with the heads, Im sure anyone whose been around Terminators long enough has probably heard at least a million times about the “4 thread vs 9 thread heads”. So according to the many forums and research I have done I found that the heads were built in this order. Hopefully this information is correct because there is a ton of different info from different people stating different things regarding ‘03-04 Cobra heads.

“The earliest heads had casting numbers that ended in -"AF" and "-AG" with a major revision in '03 that ended in "-DA" (all four-thread plugs). The newer '04 heads with the nine threads end in "-DB" with the final revision in '05 ending in "-DC".

The “DC” heads supposedly addressed the cooling issue etc and are the ones to get when buying heads from what I understand.

Once I removed my heads I noticed that I had an “AG” head on the passenger side and a “DA” on the drivers with a blue stripe on its intake side, I assume meaning that my drivers head had been serviced at some point. I was told the blue paint was for dealerships to know the head had already been replaced/worked on, but honestly who knows why its there. Some say it’s completely irrelevant. Anyways both heads are 4 threaded heads and I plan to replace the drivers side head instead of having it rebuilt and using it again with that timesert. I also saw that a rocker arm had come off on cylinder #8 on the same valve that dropped the seat.

So now that Ive decided to buy another drivers side head at minimum Im finding that good shape “DB/DC” 9 thread heads can be had for around the same price as rebuilding my current 4 thread heads. Question is should i just buy a 4/9 thread replacement head for the drivers side and have the 4 thread passenger head rebuilt with it (keep passenger side with a 4 thread head) or buy two used “DB/DC” 9 thread heads and just upgrade both now while its apart.

I was quoted by a local shop that it would cost $429 per head and I buy parts. Head rebuild kits seem to go for around $800. So you figure $429 x 2 = $858 (headwork) + $800 (parts) = $1,658 and thats IF i reuse my Drivers timeserted head. Add another $500 to that if i replace just the drivers head. Granted after all that Id still have 4 thread older model heads. Id be at about $2100-2200 all said and done according to my math. I can get a set of decent used “DB/DC” heads for about $2k but they wont be rebuilt.. I have found a few with very low miles though.

What would you do?


SEE PICS BELLOW

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[sigjig]

Am I missing something or not? In the pictures of the heads that you posted I see many more than 4 threads in the spark plug holes. If these are are the DA heads, why don't we see 4 threads?

I'm in a simile;ar station with my '03. I believe Im getting the tick issue. I'm just beginning to research my options. I will take a video soon to post, and ask for opinions.

Good luck with your solutions.

 

[03_Zinc_Termi]

Am I missing something or not? In the pictures of the heads that you posted I see many more than 4 threads in the spark plug holes. If these are are the DA heads, why don't we see 4 threads?

I'm in a simile;ar station with my '03. I believe Im getting the tick issue. I'm just beginning to research my options. I will take a video soon to post, and ask for opinions.

Good luck with your solutions.

The picture with more than 4 threads is cylinder 8 which has a timesert installed, thats why you see so many threads. This picture is what the rest of the cylinders look like.

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[sigjig]

The picture with more than 4 threads is cylinder 8 which has a timesert installed, thats why you see so many threads. This picture is what the rest of the cylinders look like. View attachment 1437380


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I see now the 4 threads stand out very clearly..