2004 Mustang Cobra Spark Plugs

[Hybbs]

I'm sure this has been covered a hundred times on this forum but please bear with me. I've had my 2004 Cobra for a couple of years and decided to change the plugs. I pulled the drivers side plugs and they were Autolite XP 103's. My car is pullied and tuned, makes 452 whp and 473 rwtq. THe plugs looked a little worn, but not too bad. I've heard these plugs are one heat range colder than stock and are a good upgrade. I checked the gap on said plugs, and they were gapped at .042-.043. From everything I've read, most Cobra spark plugs are being gapped at .032-.035. My question is should I stick with the Autolite's or should I switch to the NGK IX6 that everyone seems to be running these days??? If I stay with the Autolite's should I gap them at .032-.035???

Thanks in advance for any advice.

 

[Bdubbs]

The autolite 103 are suppose to a good plug. I've run both ngk tr6 and tr6ix. currently running the tr6's and will continue to do so. Some cars are picky with plugs I've found out. I'd throw in a new set and gap them down to .035 and see how they work.

 

[Hybbs]

The autolite 103 are suppose to a good plug. I've run both ngk tr6 and tr6ix. currently running the tr6's and will continue to do so. Some cars are picky with plugs I've found out. I'd throw in a new set and gap them down to .035 and see how they work.

I appriciate the input B dizzle

 

[roy_1031]

I had good luck with the 103's when I was pulley'd only. Similar numbers to yours I believe I was gapped at .032.

 

[2011 gtcs]

I'm running the Motorcraft Sp-471s gappped at 28.

 

[P49Y-CY]

From what I've read, and someone please correct me if I'm wrong, but for best idle, driveability, etc., you want to keep the gap as wide as you can (close to stock) before getting blowout.

For an upper-only Eaton you will usually have to be gapped down to like .032 - .035 or it will blowout. So I would say that if it's working for you at the wider gap, you don't need to change it.

103's are good, but I found my cars idle smoother with the iridium tr6ix

 

[Hybbs]

I stayed with the Autolite's XP 103's. I split the difference with everyone's advice on the gap and gapped them at about .033-.034. Cars seems to be idling perfect. Took it for a quick ride with no issues. Thanks for everyone's input.

 

[01yellercobra]

From what I've read, and someone please correct me if I'm wrong, but for best idle, driveability, etc., you want to keep the gap as wide as you can (close to stock) before getting blowout.

For an upper-only Eaton you will usually have to be gapped down to like .032 - .035 or it will blowout. So I would say that if it's working for you at the wider gap, you don't need to change it.

103's are good, but I found my cars idle smoother with the iridium tr6ix

You're correct on the gap. You always want to run the widest gap possible. It gives you a better burn across the rpm range.

I had a set of 103's separate the ceramic from the metal casing. I've run TR6's since then. My current su is gapped at .035".

 

[Gary101386]

This brings up a good point... and not to hijack thread, but do these same rules apply for E85? Also at what point are people changing plugs? Ive got 42K miles.

 

[01yellercobra]

This brings up a good point... and not to hijack thread, but do these same rules apply for E85? Also at what point are people changing plugs? Ive got 42K miles.

The basic rule about running as wide of a gap as possible does. I don't know much of a difference E85 makes though. I've always changed plugs around 10k miles on my blown vehicles.

 

[98 Saleen Cobra]

I run Ngk br7ef plugs. Great success with them

 

[c6zhombre]

This brings up a good point... and not to hijack thread, but do these same rules apply for E85? Also at what point are people changing plugs? Ive got 42K miles.

I've been running E85 for near 6 years now, I'm changing the plugs (TR6) once a year or about 1500-2000 miles or so. I try to change the oil, plugs, and fuel filter on the same day. I'm running 22psi and gap the plugs at .026~.028. I on occasion will run pump 93 gas, lower the boost to 18 and I leave the plugs gapped the same. The car performs great either fuel type.

 

[Gary101386]

I've been running E85 for near 6 years now, I'm changing the plugs (TR6) once a year or about 1500-2000 miles or so. I try to change the oil, plugs, and fuel filter on the same day. I'm running 22psi and gap the plugs at .026~.028. I on occasion will run pump 93 gas, lower the boost to 18 and I leave the plugs gapped the same. The car performs great either fuel type.

22psi, nice. I'm spinning 13.5


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