Plugs

[Grenade]

If I end up running with the 2.8 pulley, and stock lower, stock blower, I should end up around 450 hp. Hopefully. Should I change the plugs to one step colder? I feel like I should. What would be a good plug to consider? Thanks for your helpfull suggestions.

[Video_Master]

I was running 465 RWHP with the stock plugs just fine. No need till you come to that magical 500 number.

[Kafn8td]

Depends on what's in there now. There have been 3 different plugs in the 03/04 Cobras, Early 03's came with AGSF12FM1's (coldest) my 04 came with 22FM1's (NGK TR6 equivilant) and some cars came with 32FM1's (hottest). if you have 12's (doubt it) or 22's you are ok.

[Grenade]

Depends on what's in there now. There have been 3 different plugs in the 03/04 Cobras, Early 03's came with AGSF12FM1's (coldest) my 04 came with 22FM1's (NGK TR6 equivilant) and some cars came with 32FM1's (hottest). if you have 12's (doubt it) or 22's you are ok.
I'll pull one out and see. Thanks

[ClOckwOrk]

its pretty easy. look at what you have, and go one step colder. if it makes your car run like butt, it was rich in the first place. if it runs fine, your good. if you dont go colder on the plugs, just bring your timing back a degree or two

[Grenade]

Ok, Thanks.

[Kafn8td]

Bringing the timing back a degree or 2 on a Cobra is 20+hp!

[Grenade]

Bringing the timing back a degree or 2 on a Cobra is 20+hp!
WTF? Really, or are you kidding? We shoulda checked my plugs today. I'll do that later, and get back.
Thanks Kaf, for helping me take the :gay: out of my Cobra today.

[Kafn8td]

At least 20! Probably more! 93 octane and 23 degrees is the sweet spot!

[Shadowgray03]

WTF? Really, or are you kidding? We shoulda checked my plugs today. I'll do that later, and get back.
Thanks Kaf, for helping me take the :gay: out of my Cobra today.

There is no set in stone rule as to how much power will be gained from timing alone. If 2 deg was worth 20 horse then going from the stock 15 deg to 23 deg on a bone stock car would be worth 80hp and that simply is not the case.

[termin8r]

There is no set in stone rule as to how much power will be gained from timing alone. If 2 deg was worth 20 horse then going from the stock 15 deg to 23 deg on a bone stock car would be worth 80hp and that simply is not the case.
not only that, but with timing you do come to a point where more/less timing will result in no increase in power. it just gives you a higher chance of detonation.

[OrangeFox]

I know on my car it always starts to detonate at 22 degrees of timing so I usually run around 20 to 21!

[Kafn8td]

yes, if only the world was linear everything could be explained. MBT mean anything to anybody?

[Grenade]

yes, if only the world was linear everything could be explained. MBT mean anything to anybody?
Mean Base Timing? Just a guess.

[Grenade]

Depends on what's in there now. There have been 3 different plugs in the 03/04 Cobras, Early 03's came with AGSF12FM1's (coldest) my 04 came with 22FM1's (NGK TR6 equivilant) and some cars came with 32FM1's (hottest). if you have 12's (doubt it) or 22's you are ok.
I just checked. I have the 22's. I only pulled one. I should have pulled them all and checked the gap. What would be a good gap, with a 2.8 and stock blower, About 13 psi or so?

[Shadowgray03]

yes, if only the world was linear everything could be explained. MBT mean anything to anybody?Mean best timing for the 03-04 cobra is commonly agreed upon as 23 deg total timing advance but even so that doesnt mean that everyone can run 23deg or that you even want to. It simply means that going past that will give you no gains. Many guys dont see any gains by going from 21 to 23, others see a few ponies. In the end the only way to be certain is to try it and properly listen for detonation while the car hits max load.

Generally speaking on a stock cobra by doing nothing but tweaking the tune your only going to get 25rwhp or so. There is generally a very small window where 2 deg timing will net you 20rwhp, as a rule of thumb many consider 5-6rwhp a good approximation for HP per deg of timing.


I know on my car it always starts to detonate at 22 degrees of timing so I usually run around 20 to 21! And if you werent on an eddy current dyno with the car hitting a full load you probably never would have known you were getting detonation either. The extra 5-10rwhp you get from running an extra 2 deg of timing just isnt worth it. The inadible detonation can rob power and over the long haul will shorten the life of your engine.


I just checked. I have the 22's. I only pulled one. I should have pulled them all and checked the gap. What would be a good gap, with a 2.8 and stock blower, About 13 psi or so?If it were me I would the the agsf12 at .038. Gap may need to be tweaked if you have blowout or low rpm studder.

[Grenade]

So get the colder stock ones? Or go aftermarket? {Brisk etc.} Gap to what? I'm going to be running about 13-14 psi. I'll then tune it. And hope for 450rwhp. Then that's about it for this year. Ported for next year. I'd like to run very low 12's with 450rwhp. Can I run 11's without a port? I will try very hard.

[Video_Master]

I would suggest going wth the recomendation of whoever is doing the tuning of your car as for which plugs to get and what to gap them at.

[Shadowgray03]

So get the colder stock ones? Or go aftermarket? {Brisk etc.} Gap to what? I'm going to be running about 13-14 psi. I'll then tune it. And hope for 450rwhp. Then that's about it for this year. Ported for next year. I'd like to run very low 12's with 450rwhp. Can I run 11's without a port? I will try very hard.Like anything performance related there are a lot of "guidlines" on where to start. For example Denso recommends going 1 step colder for every 75-125 hp you add. Using that as a guide and guestimating stock rwhp at 375, once you get to 450 you will probably want to go a step colder.

Plugs are a major component in the cooling system and their heat range is actually their ability to pull heat from the combustion chamber and into the head where its handled by the cooling system.

Copper plugs are generally the most robust but dont yield quite as good a spark as the platinum and then at the other end of the spectrum you have iridiums which are not only expensive but very fragil. Where as mild detonation usually will have little effect on a copper plug it will often destroy an iridium plug.

Ive tried denso iridium and honestly didnt care for the way the car ran with em in and they certainly werent worth the $6 each. Id probably just stay with NGK, Autolites or even the stock motorcraft just a range colder.

[Grenade]

So the stock 12's would be ok? Gapped to what?

[OrangeFox]

If you take it to Dan he will throw TR6's in it right away, that is all he puts in Cobra's. All I know is that it made my car have a slight miss at low RPM's with those plugs. I took them out and put a new set of stock ones in and it cleared her right up. But now with what I am doing I put the TR6's back in.

[Shadowgray03]

So the stock 12's would be ok? Gapped to what?As I mentioned above, if it were me I would just get the motorcraft agsf12's and start with em gapped at .038. If you have blowout on the dyno shrink the gap. If you have a low rpm studder (ie holding steady 1800-2500rpm in like 2nd gear) then open the gap.

With my stock engine and KB I was having the low rpm studdering that Cobracrazy was having and I tried a few different plugs and gaps and had the best drivability with stock motorcraft plugs.

[termin8r]

i just threw some TR6's in mine gapped at .036, no problems yet.