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Ask your spark plug, wires and coil questions here

214K views 469 replies 172 participants last post by  amc49 
#1 ·
I've decided to make an "ignition" thread.

and post up answer's to the more commonly asked questions.

Do I need to upgrade my coil?

Simply put.... No
Stock coils will provide enough spark to support over 700whp. The average 4 tower coil will put out between 36-40k volts most aftermarket coils put out only 42k MAX. You will not see any gains what so ever by swapping out a working stock coil for an aftermarket one.

Do I need to go with those really expensive plugs?

Again.... No

Unless you have a HEAVILY Modded (MORE THAN BOLT ONS) engine there is no need to use any other plug than STOCK. You CAN re-gap the stock plugs to .060 (in most cases) and you will get a smoother idle and the overall running of the car will be improved... but just slightly. When you open up the gap it take MORE voltage to jump the gap and make spark.. therefore wider the gap the hotter the spark.

Now if you are running Nitrous of Forced Induction then yes you can benefit from changing plugs. I highly recommend the MotorCraft AZFS22C f4 sparkplugs. They are copper cored (which is one of the BEST conductors of electricity.. better than Iridium) and will provide a wider,stronger spark. They also work VERY well with NA engines,and at $8 a set you cant go wrong.

Should I change plug wires?

Yes

Changing your plugs wires is problely the most effective ignition upgrade you can do on a Focus. Any descent low resistance wire is MILES beyond the stock wires... I can not say how much I despise stock wires for there inability to carry good voltage. Remember the bigger the wire the better... smaller wires will heat up internally and heat greatly reduces their ability to conduct electricity.


Well thats your basic ignition questions covered... feel free to ask any questions that you have.

John
 
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#3 ·
I can do that....... let me wave my magic wand.... sprinkle some fairy dust.... and abera cadabera [poof] now its a sticky!!!
 
#6 ·
The new part number for the copper Motorcrafts is: SP-463
Some Dealers and Parts Stores will be able to cross reference to the old AZF--- number, but if not, use the new one.

I'd also add, that NA cars do extremely well with the Motorcraft copper plugs.
They're cheaper, and provide better spark than the stock platinums.
More often than not when it's time to change plugs, members are using the copper plugs.

As far as openning the gap to .060.
That's generally done when swapping in the Motorcraft copper plugs,
and not neccessarily with the factory platinum plugs.
Openning the gap also goes hand in hand with swapping in better plug wires.
 
#7 ·
Actually I have done the .060 gap on the plats with very good results in several other Foci.
 
#9 ·
I really like the Taylor wires:
http://www.focusfanatics.com/forum/showthread.php?t=55133
^^^Lots of pics and links in the latter half of the thread.

Actually I have done the .060 gap on the plats with very good results in several other Foci.
That's good to know. [;)]
I'm just personally not a fan of the platinums, especially when considering the performance to price ratio.
 
#10 ·
Ordered a set from Summit today. The 8.2mm RED wires. $46 and change plus the $10 'Handling' charge. [confused]

Lots of good info on the link you provided - Thanks!

Now I can't wait to get them installed with the new plugs![wrenchin]

Anything special I need to know about changing these plugs/wires? Special Tools?
I've been changing them for years on OHV V6's/V8's/V10's, but this will be my first on a Twin-Cam engine.
 
#11 ·
Nope, nothing special.... it takes normal tools for the plugs and just your hand for the wires.
 
#13 ·
Normally plugs torque to 23ft/lbs

I've done them for so long I can get them at spec without a torque wrench.
 
#16 ·
Stock wires... I would go about 50-75k.. since stock wires tend to get brittle and crack.

Aftermarket.. about the same... and aftermarket wire should hold up better.

You can change them where ever you feel like... I know guys that do it once a year... just really depends on the owner and the condition of the wires.
 
#18 ·
spark plug gap

I'm installing new Denso spark plugs into the SVT and have a few questions. First do i need to gap to .065 if I only have MSD wires (the manual calls for .051)? Second, I know this is a noob question, but how can I correctly read the spark plug gauge, the circular one? Thanks again
 
#19 ·
If you're still running the stock coil, it might or might not be able to put out enough voltage to cover the larger gap. You can try and see by gapping them and then driving the car afterwards to see if it misfires. As far as the plug gauge goes, it should be two sided. Each tick mark should represent one unit of measure or it may go by two's depending on who makes it. Just use the side that measures in hundredths and to get the appropriate gap distance, I would center the center electrode at the desired mark by wiggling the tool in between the ground electrode and center electrode. This should create a groove in the tool if the spacing was tight to begin with.
 
#57 ·
I would center the center electrode at the desired mark by wiggling the tool in between the ground electrode and center electrode. This should create a groove in the tool if the spacing was tight to begin with.
DO NOT WIGGLE THE TOOL IN BETWEEN THE PLUG! You will have a good chance of ruining the plug, theirs a hole on the gapper and what you want to do is to use that to gao it bigger. Especially with iridium plugs you can rub of the coating and basiacally be back to a platinum coating (some of the companies put on a coating rather than full iridium)
 
#20 ·
I've read that .60 is a decent gap for NA cars. The stock coil should be able to handle that with no problem. If you can get yourself a feeler gague from Sears, a local tool shop, or even a local parts shop it will be much easier for you to gap the plugs accurately.
 
#24 ·
What plug gap? I aint got any gap! lol

We'll ok, around .062-.065

My ground electrode is cut back 2mm so it is barely covering the copper core! I then indexed the plugs so they were all facing the exhaust ports This took a few boxes of SP-463s to find 4 plugs that would screw in facing the direction I wanted. Expensive but worth the 4hp increase at the wheels. I threw in an MSD coil and 8.5mm wires for good measure. This made a VERY noticeable difference across the board.

I suggest other people try this combination!~ I can promise you if you do it correctly, you won't be disappointed! [80?]
 
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