Spark plug gap ?

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The wider that works, the better. A larger spark, the whole point of hi-energy ignitions. Standard compression hi energy coils will jump .060
 
kingvern said:
What should I gap my plugs at in a 520 with Indy ez heads and 10-6-1 compression. Thanks Vern
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With only 10.6 compression I'd use NGK 6987 plugs. Those are #6 heat range with a projected tip and come out of the box with a 0.043 gap. That is the plug I use on my pump gas engines. If the heads are properly ported it should make around 700 hp on unleaded premium provided the cam, intake and carb are up to it.
 
MoparLeo said:
The wider that works, the better. A larger spark, the whole point of hi-energy ignitions. Standard compression hi energy coils will jump .060
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Tell us how that works and why.
 
AndyF said:
With only 10.6 compression I'd use NGK 6987 plugs. Those are #6 heat range with a projected tip and come out of the box with a 0.043 gap. That is the plug I use on my pump gas engines. If the heads are properly ported it should make around 700 hp on unleaded premium provided the cam, intake and carb are up to it.
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I agree w/ Andy, that's the plugs I wound up with in my 440/505 .
 
MoparLeo said:
The wider that works, the better. A larger spark, the whole point of hi-energy ignitions. Standard compression hi energy coils will jump .060
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If I remember right, MSD says .045 w/ their 6`s .
 
With MSD 6-AL they say .060". No mention of exact motor or anything else. Seems to work just fine on my 340.
 
If I need more than a .040 gap I either cut the ground wire back or buy plugs with a cut back ground wire.

When power levels go up, the gap gets closer. Just a fact. Use a power adder, gap gets closer.

Battery fired ignitions are like that.
 
kingvern said:
Dave said to run 5672A ngk
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Those are racing plugs. If it is a street car you should use a resistor plug. The #6987 is a resistor plug and it already comes with the wider 0.043 gap so you don't have to regap them. Also, the #6987 has a more projected tip which is usually worth a little bit of power.
 
Keep something in mind.........Very much gap more than needed to develop the power in your combo is just creating high voltage stress on the components......rotor, cap, wires, etc. You can "punch" spark right through a rotor to the mechanism/ shaft below, and this is much harder on components in the long run.
 
Well.....and I'm sure the "experts" will come out of the woodwork to tell me how wrong I am, but this is my view.

The ignition of the air fuel mixture can only be lit one time. It does not take "much" of a spark to do it. Once lit, it's lit. You cannot light it a second time OR more than it's lit from the start.

Saying a wider gap creates "more spark" to "light more" mixture is like sayin one girl is "more pregnant" than another.
 
What was the point of the Magneto ignition ? To supply higher voltages at higher rpms and cylinder pressure that puts the spark out on standard type ignitions. What was the point of Resistor plugs ? To just cut down on radio interference ? how about allowing wider plug gaps which helped to smooth out ignition impulses and increase efficiency/mileage at the same time. Also remember that it is true that you can only light the mixture once, but you also only get 1 chance to do it. The ignition is a "system" plugs, coil, timing, coil saturation, ignition pulse, .............. Just do what the mfg. of your components recommend. They are the ones with the high dollar equipment and extensive lab time to prove their product. Or get a million opinions and pick one.
 
MoparLeo said:
What was the point of the Magneto ignition ? To supply higher voltages at higher rpms and cylinder pressure that puts the spark out on standard type ignitions. What was the point of Resistor plugs ? To just cut down on radio interference ? how about allowing wider plug gaps which helped to smooth out ignition impulses and increase efficiency/mileage at the same time. Also remember that it is true that you can only light the mixture once, but you also only get 1 chance to do it. The ignition is a "system" plugs, coil, timing, coil saturation, ignition pulse, .............. Just do what the mfg. of your components recommend. They are the ones with the high dollar equipment and extensive lab time to prove their product. Or get a million opinions and pick one.
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Back in the day, we were racing a 426 hemi, the year we switched to superstock , and raised the comp ratio, it developed an intermittent miss, not consistent, but all the way thru the 1/4 mile.. We finally deducted the extra comp. was blowing the fire out of the plugs ''or whatever". We put an MSD 6 in in and cured it instantly !! The plugs would last all summer after that. I`ve used MSD`s in everything since. with .045 gap.
 
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